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https://www.quantumstudy.com/a-strength-smooth-tunnel-is-dug-through-a-spherical-planet-and-is-perpendicular-to-the-planets-axis-of-rotation-which-is-fixed-in-space-the-planet-rotates/ | [
"# A strength smooth tunnel is dug through a spherical planet and is perpendicular to the planet’s axis of rotation, which is fixed in space. The planet rotates with the angular velocity ω so that objects in the tunnel have no acceleration relative to the tunnel. Find the value of ω.\n\nQ: A strength smooth tunnel is dug through a spherical planet and is perpendicular to the planet’s axis of rotation, which is fixed in space. The planet rotates with the angular velocity ω so that objects in the tunnel have no acceleration relative to the tunnel. Find the value of ω.\n\n(a) $\\sqrt{\\frac{4}{3}} \\pi G \\rho_0$\n\n(b) $\\sqrt{\\frac{2}{3}} \\pi G \\rho_0$\n\n(c) $\\sqrt{\\frac{1}{3}} \\pi G \\rho_0$\n\n(d) $2 \\sqrt{\\frac{4}{3}} \\pi G \\rho_0$\n\nAns: (a)"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7484738,"math_prob":0.9942331,"size":451,"snap":"2022-27-2022-33","text_gpt3_token_len":142,"char_repetition_ratio":0.16331096,"word_repetition_ratio":0.0,"special_character_ratio":0.35254988,"punctuation_ratio":0.06451613,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9980784,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-07-04T06:31:24Z\",\"WARC-Record-ID\":\"<urn:uuid:9bbdb39b-5b3a-4d52-b1d1-2e199046f6b1>\",\"Content-Length\":\"52750\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:08f1fec9-54b3-430d-bb6b-d986833a50b5>\",\"WARC-Concurrent-To\":\"<urn:uuid:de908aea-710b-43a1-874f-f1a607a996d8>\",\"WARC-IP-Address\":\"103.133.214.171\",\"WARC-Target-URI\":\"https://www.quantumstudy.com/a-strength-smooth-tunnel-is-dug-through-a-spherical-planet-and-is-perpendicular-to-the-planets-axis-of-rotation-which-is-fixed-in-space-the-planet-rotates/\",\"WARC-Payload-Digest\":\"sha1:TH2HPVCXGSLDHHIVQPEHPWKL2K5D3VZA\",\"WARC-Block-Digest\":\"sha1:A4EWU2MC3YHLBSOK7Z6IFNDU7HF3KXDH\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-27/CC-MAIN-2022-27_segments_1656104354651.73_warc_CC-MAIN-20220704050055-20220704080055-00526.warc.gz\"}"} |
https://docs.arnoldrenderer.com/exportword?pageId=70746280 | [
"Date: Wed, 27 Oct 2021 10:50:50 +0000 (UTC) Message-ID: <654809145.34819.1635331850577@[52.200.175.11]> Subject: Exported From Confluence MIME-Version: 1.0 Content-Type: multipart/related; boundary=\"----=_Part_34818_473868297.1635331850575\" ------=_Part_34818_473868297.1635331850575 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Content-Location: file:///C:/exported.html Advanced (Toon)",
null,
"=20\n\n#### Indirect Diffuse\n\nThe amount of diffuse light received = from indirect sources only.\n\n=20\n=20\n=20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20",
null,
"",
null,
"",
null,
"=20 0 =20 0.5 =20 1 (default)\n=20\n=20\n=20\n\nIndirect_diffuse: 0 (default) creates a more two-dimensional lo= oking toon shading effect.\n\n=20\n=20\n=20 =20 =20 =20 =20 =20 =20 =20 =20 =20",
null,
"",
null,
"=20 0 (default) =20 1\n=20\n=20\n=20\n\n#### Indirect Specular\n\nThe amount of specularity received fr= om indirect sources only. Values other than 1.0 will cause the = materials to not preserve energy, and global illumination may not converge.=\n\n=20\n=20\n=20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20 =20",
null,
"",
null,
"",
null,
"=20 0 =20 0.5 =20 1 (default)\n=20\n=20\n\n#### Energy Conserving\n\nThe toon shader is energy= conserving by default. If thi= s is disabled, the Toon shader simply adds base, spec= ular, and transmission. Care should be taken when disabling this option as it will affect i= ndirect illumination with the toon shader.\n\n#### AOV Prefix\n\nAn optional aov_prefix that will be prepended to the toon AOVs'= names. For instance, if aov_prefix is `\"toon_\"`, the toon diff= use AOV will be written out to `\"toon_diffuse\"`. This can be used when you need to access bo= th the toon AOVs and the core's LPE AOVs."
] | [
null,
"https://docs.arnoldrenderer.com/3D\"636f0466494b77a8e15f5d20af6ab89f\"",
null,
"https://docs.arnoldrenderer.com/=3D\"1bd861d89f1d9886297c1b7bc6c41fca\"",
null,
"https://docs.arnoldrenderer.com/=3D\"bbb613714af9bdad0619ab9b5dd25cb1\"",
null,
"https://docs.arnoldrenderer.com/=3D\"18a1ad94961346f22d87aeecb1712e74\"",
null,
"https://docs.arnoldrenderer.com/=3D\"23daac9f1b392432e07dbfd71cc778d7\"",
null,
"https://docs.arnoldrenderer.com/=3D\"dd9e39ece665e680b242cfc2bcbf29e0\"",
null,
"https://docs.arnoldrenderer.com/=3D\"d53b7af35a39912d821dd6753a8ff259\"",
null,
"https://docs.arnoldrenderer.com/=3D\"319fed87c7519b83ba8867a7dc7b1cb3\"",
null,
"https://docs.arnoldrenderer.com/=3D\"368f62eec2e11c8a68b7300e70c1d553\"",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7185731,"math_prob":0.7637049,"size":1384,"snap":"2021-43-2021-49","text_gpt3_token_len":423,"char_repetition_ratio":0.14637682,"word_repetition_ratio":0.03208556,"special_character_ratio":0.37210983,"punctuation_ratio":0.15789473,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99969804,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18],"im_url_duplicate_count":[null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null,1,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-10-27T10:50:50Z\",\"WARC-Record-ID\":\"<urn:uuid:6f1fc22b-9d7f-4a99-9267-79f536677b66>\",\"Content-Length\":\"497570\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:11653b80-bfc9-4430-86fa-7e2aca587757>\",\"WARC-Concurrent-To\":\"<urn:uuid:64d01887-dbab-4468-a9df-a8faae728419>\",\"WARC-IP-Address\":\"52.200.175.11\",\"WARC-Target-URI\":\"https://docs.arnoldrenderer.com/exportword?pageId=70746280\",\"WARC-Payload-Digest\":\"sha1:LCNP2N6SED6CE3IRWB7XICBR555LOHSF\",\"WARC-Block-Digest\":\"sha1:GFMONUHZW4KZ3OQJ73EO7L3COUM7UGTH\",\"WARC-Identified-Payload-Type\":\"message/rfc822\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-43/CC-MAIN-2021-43_segments_1634323588113.25_warc_CC-MAIN-20211027084718-20211027114718-00216.warc.gz\"}"} |
https://www.arunma.com/2023/03/19/build-your-own-counting-bloom-filter-in-rust/ | [
"March 19, 2023\n\n# Build your own Counting Bloom Filter in Rust\n\nA Counting Bloom Filter is a probabilistic data structure that helps us quickly check if an element is present in a set or not. You might argue \"Hey, can't a simple Set do it?\".\n\nYes, indeed and to top it, Counting Bloom Filter is not even 100% accurate and expects us to provide the expected \"false positive rate\". Where Bloom Filters shine is that for large volumes of data it would use much lesser memory than a regular HashSet.\n\nThis post attempts an implementation of the datastructure. At the end of the post, you'll be able to build your own Counting Bloom Filter. The final code is available here.\n\nBefore we get into the implementation, let's get some properties of CBF out of the way:\n\n1. As with our traditional BloomFilter, Quotient Filter or CuckooFilter, Counting Bloom Filter is a probabilistic data structure that is used to test whether an element is a member of a set. Essentially, these filters aim to solve a class of problems called \"Membership\". A key feature that CBF offers over traditional Bloom Filter is that CBF allows deletion of inserted items.\n2. As with any probabilistic data structure, there is a chance that we might get some false positives - essentially, the response to the question \"Is an element present in the set?\" is not 100% accurate. There are times when the bloom filter would say that the element is present but it actually was not. This \"false positive\" rate is configurable through a parameter.\n3. Unlike HashSet, you cannot iterate through the values stored in the set - we can only check whether the value is present in the CBF.\n\n## Bloom Filter vs Counting Bloom Filter\n\nThe underlying storage of a BloomFilter is just a fixed-size array of bits.\n\n💡\nThis is a fantastic write-up detailing how to implement your own Bloom Filter.\n\nA Counting Bloom Filter uses a fixed-size array of counters.\n\nTo put it in crude terms, the underlying storage of Bloom Filter is a Vec<bool> (or a BitSet). With CBF, it is a Vec<u8> or Vec<u16> or Vec<u32> or a list of unsigned integers.\n\n💡\nThe counter size does not need to be 8, 16, 32 bits etc - rather, they don't need to be aligned to the datatypes. Using arbitrary bit sizes is common and is achieved by partitioning a usize integer into arbitrary bit sizes.\n\nFor illustration, our implementation of a Counting Bloom Filter will use a u8 bit counter.\n\n### Setting the stage\n\n#### 1. Declaring our struct and instantiation\n\n#[derive(Debug)]\npub struct CountingBloomFilter<T: ?Sized + Hash> {\ncounter: Vec<u8>,\nm: usize,\nk: usize,\nhasher: SipHasher24,\nexpected_num_items: usize,\nfalse_positive_rate: f64,\nlen: usize,\n_p: PhantomData<T>,\n}\n\nAs expected, our struct encapsulates a list of counters. There are two parameters that we would be accepting from the user, which are expected_num_items and false_positive_rate.\n\n1. The expected_num_items is an approximate number of items that the user would like to store in the CBF.\n2. The false_positive_rate is an estimate of False Positives/inverse accuracy that the user can live with.\n\nThe len just stores the total number of items inserted into the data structure so far. We'll discuss the m and k fields in the next section.\n\n#### 2. Number of buckets and number of hashes\n\n##### Bloom Filter\n\nIn a BloomFilter, m is simply the size of the bit vector (or underlying bits representing the membership of the various inserted values). k is the number of hash functions that each inserted value has to be run against.\n\nSo, given a value x, it will be hashed by k number of hash functions and the corresponding bit in the m buckets will be set to True.\n\nLet's consider the illustration above. Each item ( x, y, z) are hashed by 2 hash functions (represented by arrows). The resulting output are expected to be the bucket indices. Considering the total number of buckets is just 8 in the above illustration, the output of the hash function is modulo-ed to reduce the range between 0 and 7.\n\n##### Counting bloom filter.\n\nThe number of hash functions ( k ) is 2 as above and the m is 8. However, the underlying store is not a list of bits but a list of counters.\n\nThe formulas for calculating the size of m and k given the expected_num_of_items and false_positive_rate for Counting Bloom Filter are:\n\nLet's implement the optimal_m, optimal_k and the new functions\n\n\nfn optimal_m(num_items: usize, false_positive_rate: f64) -> usize {\n-(num_items as f64 * false_positive_rate.ln() / (2.0f64.ln().powi(2))).ceil() as usize\n}\n\nfn optimal_k(n: usize, m: usize) -> usize {\nlet k = (m as f64 / n as f64 * 2.0f64.ln()).round() as usize;\nif k < 1 {\n1\n} else {\nk\n}\n}\n\nimpl<T: ?Sized + Hash + Debug> CountingBloomFilter<T> {\npub fn new(expected_num_items: usize, false_positive_rate: f64) -> Result<Self> {\nvalidate(expected_num_items, false_positive_rate)?;\nlet m = optimal_m(expected_num_items, false_positive_rate);\nlet counter = vec![0; m];\nlet k = optimal_k(expected_num_items, m);\nlet random_key = generate_random_key();\nlet hasher = create_hasher_with_key(random_key);\nOk(Self {\ncounter,\nm,\nk,\nhasher,\nexpected_num_items,\nfalse_positive_rate,\nlen: 0,\n_p: PhantomData,\n})\n}\n\nAs you can see, only the \"estimated number of items to be inserted\" and the \"false positive rate\" is needed to construct our Counting Bloom Filter.\n\n#### 3. Hashers\n\nOnce we calculate the optimal number of hash functions (k), we need to create k independent hash functions. One approach is to have a repository of hash functions and initiate them with a random key. However, there is a simpler approach that is proposed by Adam Kirsch and Michael Mitzenmacher, where we could simulate additional hash functions with the help of two base hash functions.\n\nQuoting the paper:\n\nThe idea is the following: two hash functions h1(x) and h2(x) can simulate more than two hash functions of the form gi(x) = h1(x) + ih2(x). In our context i will range from 0 up to some number k − 1 to give k hash functions, and the hash values are taken modulo the size of the relevant hash table.\n\nSpecifically, only two hash functions are necessary to effectively implement a Bloom filter without any increase in the asymptotic false positive probability. This leads to less computation and potentially less need for randomness in practice.\n\nEssentially, we just need 2 independent hash functions to simulate k hash functions. Typically, Bloom Filters use 64-bit hash functions since they create enough bits for us to populate the buckets uniformly. In our implementation, we will use a 128-bit hash function and use the first and the second 64 bits to simulate two hash function outputs. We will then use these two 64-bit hashes to create more hashes.\n\nFirstly, in order to provide a random seed to our 128-bit hasher, we'll use the generate_random_key function.\n\nuse siphasher::sip128::SipHasher24;\n\n/// Generates a random 128-bit key used for hashing\nfn generate_random_key() -> [u8; 16] {\nlet mut seed = [0u8; 32];\ngetrandom::getrandom(&mut seed).unwrap();\nseed[0..16].try_into().unwrap()\n}\n\n/// Creates a SipHasher24 hasher with a given 128-bit key\nfn create_hasher_with_key(key: [u8; 16]) -> SipHasher24 {\nSipHasher24::new_with_key(&key)\n}\n\n### Building the APIs\n\nWith all the foundational functions out of the way, let us get into implementing the API - the three functions insert, contains and delete\n\n#### 1. Insert\n\nWhen an element is inserted into the filter, the counters corresponding to the element's hash values are incremented by one. This is in contrast to BloomFilter where we just set the corresponding bit. While we do this, we will also use this opportunity to keep track of the number of items inserted into the bloom filter by incrementing the len field.\n\n pub fn insert(&mut self, item: &T) {\nself.get_set_bits(item, self.k, self.m, self.hasher)\n.iter()\nself.len += 1;\n}\n\nThe get_set_bits is a helper function that takes the item to be inserted and returns the indices of all buckets for whom the counters need to be incremented. Essentially, the get_set_bits function\n\n1. Takes an item as an input\n2. Creates a 128-bit hash (done in get_hash_pair)\n3. Splits the 128-bit hash into 2 parts, thereby creating the 2 base hashes (done in get_hash_pair)\n4. Creates k hashes out of the 2 base hashes using the Kirsch and Mitzenmacher method\n5. Since we just have m buckets and the hash function output could be bigger, we do a modulus of m on each hash output. This returns k bucket indices on m . These are the indices of the counters in the bucket that needs to be incremented.\n fn get_set_bits(&self, item: &T, k: usize, m: usize, hasher: SipHasher24) -> Vec<usize> {\nlet (hash1, hash2) = self.get_hash_pair(item, hasher);\nlet mut set_bits = Vec::with_capacity(k);\nif k == 1 {\nlet bit = hash1 % m as u64;\nset_bits.push(bit as usize);\nreturn set_bits;\n}\nfor ki in 0..k as u64 {\nlet bit = hash % m as u64;\nset_bits.push(bit as usize);\n}\nassert!(set_bits.len() == k);\nset_bits\n}\n\n/// Computes the pair of 64-bit hashes for an item using the internal hasher\nfn get_hash_pair(&self, item: &T, mut hasher: SipHasher24) -> (u64, u64) {\nitem.hash(&mut hasher);\nlet hash128 = hasher.finish128().as_u128();\nlet hash1 = (hash128 & 0xffff_ffff_ffff_ffff) as u64;\nlet hash2 = (hash128 >> 64) as u64;\n(hash1, hash2)\n}\n💡\nThe wrapping_add, wrapping_mul and other wrapping functions allow for overflow of numbers without triggering a panic.\n\neg.\n\nlet a: u16 = 65534;\nlet b = a.wrapping_add(1); // 65535\nlet c = a.wrapping_add(2); // 0\n\n#### 2. Contains\n\nAs you might have guessed already, testing whether an item is present in the filter is just a matter of computing the hashes for the item and checking whether the counters in the bucket corresponding to the hashes have a non-zero value.\n\n\npub fn contains(&self, item: &T) -> bool {\nself.get_set_bits(item, self.k, self.m, self.hasher)\n.iter()\n.all(|&i| self.counter[i] > 0)\n}\n\n#### 3. Delete\n\nThe deletion operation is just an inverse of the insertion operation with two additional nuances.\n\n1. We can only delete an item that is already present in the filter. So, we check for it by calling the contains.\n2. Our counter can never be less than 0. So, we use the saturating_sub function to ensure that.\n\tpub fn delete(&mut self, item: &T) {\nlet is_present = self.contains(item);\nif is_present {\nself.get_set_bits(item, self.k, self.m, self.hasher)\n.iter()\n.for_each(|&i| {\nself.counter[i] = self.counter[i].saturating_sub(1);\n});\nself.len -= 1;\n}\n}\n\n#### 4. Estimated count\n\nAlthough Counting Bloom Filter is not the best data structure to get an estimated count of an item, it is not uncommon to see instances where the function is implemented. Estimated count is arrived at by looking at all the counter values and picking the minimum of those values. The reasoning behind choosing minimum and not maximum or median is that a counter could be incremented by several items due to hash collisions. Minimum is chosen to avoid the skew created by high-frequency elements and to be fair to the low-frequency elements.\n\n pub fn estimated_count(&self, item: &T) -> u8 {\nlet mut retu = u8::MAX;\nfor each in self.get_set_bits(item, self.k, self.m, self.hasher) {\nif self.counter[each] == 0 {\nreturn 0;\n}\nif self.counter[each] < retu {\nretu = self.counter[each];\n}\n}\nretu\n}\n💡\nWe will revisit this discussion when we build our own CountMinSketch later.\n\n### Overflow\n\nAlthough not included in our implementation, I felt that a discussion on this topic is important.\n\nIn our example, we decided that our counter is represented by an unsigned 8-bit integer with a maximum value of 255. What if subsequent item insertions attempt to increment the value of that counter? This would result in an overflow and in Rust, a panic. To avoid overflowing, the counter could be capped/saturated at the maximum value. This essentially means that subsequent insertions into that bucket will have no effect on the filter's state for that counter.\n\nThere are two common workarounds to solve overflows:\n\n1. Freezing\n2. Dynamic resizing\n\n#### 1. Freezing\n\nFreezing is a process where\n\n1. the buckets are scanned for counters that have already reached the maximum value.\n2. reset the counter to a threshold value (around 80% of the maximum value). For u8 that's approximately 200.\n\n#### 2. Dynamic resizing\n\nThe other simpler yet computationally expensive alternative is to resize the counter to accept larger values. Say, promoting the datatype from u8 to u16. This involves creating a new counter list, copying the existing counters and replacing the old list with the new one.\n\n### Code\n\nComplete code is here."
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7936797,"math_prob":0.94544166,"size":12160,"snap":"2023-40-2023-50","text_gpt3_token_len":3002,"char_repetition_ratio":0.13384336,"word_repetition_ratio":0.01711984,"special_character_ratio":0.2524671,"punctuation_ratio":0.1468085,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.98214024,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-09-22T06:13:25Z\",\"WARC-Record-ID\":\"<urn:uuid:29c2a16f-88d8-4e01-9087-253dbf404ee6>\",\"Content-Length\":\"38915\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:d5f8a62c-b203-4aea-9977-c7e402f48cbf>\",\"WARC-Concurrent-To\":\"<urn:uuid:8aa19b81-2466-41e2-aa57-db8e2c39aeef>\",\"WARC-IP-Address\":\"146.75.39.7\",\"WARC-Target-URI\":\"https://www.arunma.com/2023/03/19/build-your-own-counting-bloom-filter-in-rust/\",\"WARC-Payload-Digest\":\"sha1:YO4RHPOWW4A3NVZ2ESUKOYNHMVFGAD2B\",\"WARC-Block-Digest\":\"sha1:I5BFSOTPRX6EN72QKJKMLTDW4CIZSTWZ\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-40/CC-MAIN-2023-40_segments_1695233506329.15_warc_CC-MAIN-20230922034112-20230922064112-00410.warc.gz\"}"} |
https://books.google.com.jm/books?id=Meu1MaOdmO8C&lr= | [
"# Mathematical Dictionary and Cyclopedia of Mathematical Science: Comprising Definitions of All the Terms Employed in Mathematics - an Analysis of Each Branch, and of the Whole, as Forming a Single Science\n\nA.S. Barnes & Company, 1855 - Mathematics - 592 pages\n\n### Popular passages\n\nPage 215 - A Circle is a plane figure bounded by a curved line every point of which is equally distant from a point within called the center.\nPage 217 - If two triangles have the three sides of the one equal to the three sides of the other, each to each, the triangles are congruent.\nPage 140 - The circumference of every circle is supposed to be divided into 360 equal parts, called degrees ; and each degree into 60 equal parts, called minutes ; and each minute into 60 equal parts, called seconds ; and these into thirds, etc.\nPage 180 - The part of the equation which is on the left of the sign of equality is called the first member ; the part on the right of the sign of equality, the second member.\nPage 80 - Then multiply the second and third terms together, and divide the product by the first term: the quotient will be the fourth term, or answer.\nPage 400 - Multiply the divisor, thus augmented, by the last figure of the root, and subtract the product from the dividend, and to the remainder bring down the next period for a new dividend.\nPage 217 - If two triangles have two sides, and the included angle of the one equal to two sides and the included angle of the other, they are equal in all their parts.\nPage 124 - Subtract the cube of this number from the first period, and to the remainder bring down the first figure of the next period for a dividend.\nPage 360 - Three lines are in harmonical proportion, when the first is to the third, as the difference between the first and second, is to the difference between the second and third ; and the second is called a harmonic mean between the first and third. The expression 'harmonical proportion..."
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.9165518,"math_prob":0.97657585,"size":2906,"snap":"2023-40-2023-50","text_gpt3_token_len":557,"char_repetition_ratio":0.12818746,"word_repetition_ratio":0.050314464,"special_character_ratio":0.19993117,"punctuation_ratio":0.084812626,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.997434,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-12-05T18:02:03Z\",\"WARC-Record-ID\":\"<urn:uuid:0c4fe611-93e8-4213-8401-9d881e76e488>\",\"Content-Length\":\"63858\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:f84e49c7-8996-4fd9-8a1f-97285cff58a0>\",\"WARC-Concurrent-To\":\"<urn:uuid:05779227-3ddf-4be1-aae8-b9e5cd1f6140>\",\"WARC-IP-Address\":\"172.253.115.138\",\"WARC-Target-URI\":\"https://books.google.com.jm/books?id=Meu1MaOdmO8C&lr=\",\"WARC-Payload-Digest\":\"sha1:5W3TFHCJO6BF3IMBZ4OPTOGUTXV5RKMV\",\"WARC-Block-Digest\":\"sha1:VBQC32PPN4ZUBGRYWU5INCUKEOPOJ6AQ\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-50/CC-MAIN-2023-50_segments_1700679100555.27_warc_CC-MAIN-20231205172745-20231205202745-00182.warc.gz\"}"} |
https://askncertquestions.com/searchQuestion.php?q=520 | [
"Wellcome!\n\nQuestion 1. Asked on :05 February 2019:05:11:52 PM\n\n# The perimeter of a parallelogram is 60 cm and the ratio of its adjacent sides is 3:2 .If the altitude corresponding is 5 cm. Find the area of the parallelogram and the alyitude corresponding to the smaller side\n\n-Added by Himanshi Verma Mathematics » Perimeter And Area\n\nHimanshi Verma\n\nGiven\n\nRatio of side =3:2\n\nPerimeter =60cm\n\nAltitude =5cm\n\nSo let take one side as 3x and other is 2x\n\nThen perimeter of parallelogram\n\n=3x+2x+3x+2x\n\n=10x\n\nAccording to question perimeter =60cm\n\nThen\n\n10x=60cm\n\nX=60/10=6cm\n\nThen one side is =6 x 3=18\n\nAnd other is =2x6=12\n\nSo base=18cm\n\nArea of parallelogram =bxh\n\n=18x5=90cm²\n\nAltitude corresponding to smaller side\n\n90=12xh\n\nH=7.5cm\n\n-Answered by Himanshi Verma On 05 February 2019:05:26:39 PM(1295Average Rating Based on rating)\n\nYou can see here all the solutions of this question by various user for NCERT Solutions. We hope this try will help you in your study and performance.\n\nThis Solution may be usefull for your practice and CBSE Exams or All label exams of secondory examination. These solutions or answers are user based solution which may be or not may be by expert but you have to use this at your own understanding of your syllabus.\n\n#### What do you have in your Mind....\n\n* Now You can earn points on every asked question and Answer by you. This points make you a valuable user on this forum. This facility is only available for registered user and educators.\n\n## Search your Question Or Keywords\n\n#### Do you have a question to ask?\n\nUser Earned Point: Select\n\n## All Tags by Subjects:\n\nScience (2231)\nHistory (278)\nGeography (310)\nEconomics (257)\nPolitical Science (96)\nMathematics (200)\nGeneral Knowledge (5686)\nBiology (94)\nPhysical Education (20)\nChemistry (118)\nCivics (114)\nHome Science (12)\nSociology (9)\nHindi (45)\nEnglish (258)\nPhysics (1435)\nOther (97)\nAccountancy (378)"
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.91508055,"math_prob":0.57907337,"size":1312,"snap":"2021-43-2021-49","text_gpt3_token_len":374,"char_repetition_ratio":0.10091743,"word_repetition_ratio":0.0,"special_character_ratio":0.2660061,"punctuation_ratio":0.10037175,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9711347,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-10-20T00:50:07Z\",\"WARC-Record-ID\":\"<urn:uuid:d7374fb8-0925-426f-8dff-5363d667ec8d>\",\"Content-Length\":\"22216\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:4bf1f061-8670-4ec2-85ff-8668f4b6cb99>\",\"WARC-Concurrent-To\":\"<urn:uuid:61dd8a54-b3f2-4960-868c-b284c559e8ff>\",\"WARC-IP-Address\":\"148.66.137.24\",\"WARC-Target-URI\":\"https://askncertquestions.com/searchQuestion.php?q=520\",\"WARC-Payload-Digest\":\"sha1:SRID4LGXSXVR47SNXU5IOZLSSZ2LBQWN\",\"WARC-Block-Digest\":\"sha1:AJ4JBQAVUQJQISB2YNZN4TZE6VNS7HTE\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-43/CC-MAIN-2021-43_segments_1634323585290.83_warc_CC-MAIN-20211019233130-20211020023130-00456.warc.gz\"}"} |
https://stats.stackexchange.com/questions/310545/arima-forecasting-using-exogenous-variables-with-their-own-forecast-intervals | [
"ARIMA forecasting using exogenous variables with their own forecast intervals\n\nSuppose\n\nmodel <- Arima(y , xreg=cbind(x1, x2), order=(p,d,q))\n\n\nIf I am forecasting $x_1$ and $x_2$, then for forecasting $y$:\n\n1) If I use expected forecasts for $x_1$ and $x_2$ (single numbers), I simply do:\n\nforecast(model, xreg=cbind(E(future x1) , E(future x2))\n\n\n2) How about if I want to use forecast intervals for $x_1$ and $x_2$?\n\nThis post suggests that: you can draw (a lot of) random numbers from each predictive density, plug them into the model and get a predictive distribution for $y$. Then I guess taking the average prediction interval to come up with the one forecast interval for $y$. Does this make sense?"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.79057324,"math_prob":0.9985358,"size":619,"snap":"2019-26-2019-30","text_gpt3_token_len":179,"char_repetition_ratio":0.13658537,"word_repetition_ratio":0.0,"special_character_ratio":0.2907916,"punctuation_ratio":0.13178295,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9999268,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-06-26T16:05:31Z\",\"WARC-Record-ID\":\"<urn:uuid:f3068193-573f-4301-98ff-0bc4e7eaff99>\",\"Content-Length\":\"138752\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:75925656-d87e-48d1-a8af-8c1b5a4fa9c8>\",\"WARC-Concurrent-To\":\"<urn:uuid:1f82dc6a-e7d5-4a1e-b2bb-4e01e91a0bce>\",\"WARC-IP-Address\":\"151.101.193.69\",\"WARC-Target-URI\":\"https://stats.stackexchange.com/questions/310545/arima-forecasting-using-exogenous-variables-with-their-own-forecast-intervals\",\"WARC-Payload-Digest\":\"sha1:F6WQVPNKU4BSHCZYPMPX7XPN72DBS4CO\",\"WARC-Block-Digest\":\"sha1:XAAG266C4GQJGDTGTCR25NMHJNG42Z6I\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-26/CC-MAIN-2019-26_segments_1560628000367.74_warc_CC-MAIN-20190626154459-20190626180459-00522.warc.gz\"}"} |
https://epjquantumtechnology.springeropen.com/articles/10.1140/epjqt/s40507-015-0018-0 | [
"# Phase diagram of a QED-cavity array coupled via a N-type level scheme\n\n## Article metrics\n\n• 1946 Accesses\n\n• 1 Citations\n\n## Abstract\n\nWe study the zero-temperature phase diagram of a one-dimensional array of QED cavities where, besides the single-photon hopping, an additional coupling between neighboring cavities is mediated by an N-type four-level system. By varying the relative strength of the various couplings, the array is shown to exhibit a variety of quantum phases including a polaritonic Mott insulator, a density-wave and a superfluid phase. Our results have been obtained by means of numerical density-matrix renormalization group calculations. The phase diagram was obtained by analyzing the energy gaps for the polaritons, as well as through a study of two-point correlation functions.\n\n## Introduction\n\nThe recent impressive advances in the field of quantum simulators allowed to probe the many-body physics of strongly correlated systems at the level of the single quantum object. At present cold atoms trapped in optical lattices can be considered among the most promising examples of quantum simulators. By means of ultracold atomic and molecular gases, it is nowadays possible to reach a degree of control and accuracy in engineering the dynamics of many-body systems that were unimaginable in previously. As a consequence, the coherent quantum dynamics emerging from carefully tailored microscopic Hamiltonians can now be tested experimentally . It has been possible, just to recall one example, to implement the Bose-Hubbard (BH) model [2, 3] and to detect its zero-temperature superfluid (SF) to Mott insulator (MI) quantum phase transition . Other models involving spinor gases, Fermi systems, Bose-Fermi mixtures, or dipolar gases have been also devised and realized, providing an even richer phase diagram (see for example the review ). We mention the stabilization of density-wave (DW) phases for bosons, as well as more peculiar topological or supersolid orderings, which can arise in the presence of finite-range interactions .\n\nMore recently a novel kind of many-body quantum simulator has been introduced, based on the idea to use single photons as quantum objects. Since photons hardly interact in open space, the most natural way to significantly increase their interactions is to trap them into an optical QED cavity, and couple the field with atoms/molecules inside it in order to create an optical nonlinearity. If the nonlinearity is sufficiently large, the so called photon blockade sets in [7, 8], namely, the presence of a single photon inside a cavity prevents a second one to enter it. In the rotating-wave approximation, the simplest light-matter interaction scheme of this type can be accurately described by the Jaynes-Cummings (JC) model. By arranging an array of cavities coupled through the photon hopping, such to generate a competition between the hopping and the on-site nonlinearities, one can devise a setup that is well described by the so called Jaynes-Cummings-Hubbard (JCH) model .\n\nIn many respects, if one ignores dissipation, the physics emerging from the JCH Hamiltonian resembles, at low-energies, that of an effective BH model. Probably the main difference between the two systems is that, instead of having neutral bosons as building blocks of the model, in the JCH Hamiltonian one has to think in terms of polaritons, i.e., combined photonic/atomic excitations. Many different works already addressed the JCH equilibrium phase diagram with analytical, as well as numerical methods, leading to a fairly complete theoretical understanding of the nature and the location of the emerging phases and phase transitions in terms of the parameters governing the system (the field has been recently reviewed in, e.g., Refs. ).\n\nAdditional interest in cavity arrays comes from the fact that these systems can be naturally considered as open-system quantum simulators. Some related features have been recently explored . In the following we will not touch on this and consider only the ‘equilibrium’ phase diagram.\n\nThis intense activity has been very recently boosted by the first experiments on QED cavity arrays . As of today, the most concrete possibility to realize controllable and scalable quantum simulators with cavity arrays involves circuit-QED cavities .\n\nSo far the coupling between cavities has been mostly considered through photon hopping. Only few works started addressing more general schemes, where the cavity coupling can be induced also by means of non-linear elements [23, 24, 31, 32]. Such configurations include cross-Kerr interactions and/or correlated hopping terms, which lead to generalizations of the JCH model in a way similar to the extended BH (EBH) Hamiltonian for atoms with large dipole momentum loaded in optical lattices . The underlying physical model is believed to possess a much richer structure, with the emergence of exotic phases of correlated polaritons. It is particularly interesting to address these schemes in one-dimensional (1D) systems, where interactions become crucial to stabilize exotic phases of matter . These notably include a series of nontrivial density-wave (DW) states, which can arise in the strong coupling regime , as well as supersolidity and phase-separation effects [39, 40]. Extension to consider also counter-rotating terms in the ultrastrong coupling regime, thus leading to the so called Rabi-Hubbard model , have been investigated . However we are not aware of numerical investigations of coupled cavity models beyond the JCH and Rabi-Hubbard model.\n\nIn all such situations, non-perturbative, either numerical or analytical calculations are necessary. Here the density-matrix renormalization group (DMRG) algorithm [43, 44] has been employed to work out the quantitative zero-temperature phase diagram of the JCH model . This is a particularly efficient method for the statics of 1D many-body problems. Its key strategy consists in constructing a portion of the system (called block) and then recursively enlarge it. At each step, the basis of the corresponding Hamiltonian is truncated to a given value m, so that one can manage the Hamiltonian in an effective Hilbert space of fixed dimensions, as the physical system grows. This truncation is performed by retaining the eigenstates corresponding to the m highest eigenvalues of the reduced density matrix of the block.\n\nThe aim of this paper is to quantitatively study a generalization of the JCH Hamiltonian, aimed at taking into account an effective nearest-neighbor nonlinearity between cavities mediated by an N-type four-level system as discussed for two cavities in Ref. . The presence of this coupling leads to an effective cross-Kerr nonlinearity. An analysis at the mean-field level of a dissipative open EBH as an effective model for nonlinearly coupled cavities has been performed, unveiling the emergence of novel photon crystal and supersolid phases [23, 24]. Here we do not resort to the effective EBH model and analyze the full model as introduced in . Using the DMRG algorithm, we work out the 1D ground-state phase diagram. We show that a physics similar to the EBH model appears, with a rich phase diagram including gapless SF, as well as MI and DW phases of polaritons. We postpone the analysis of the interplay of driving and dissipation to a future work.\n\nThe paper is organized as follows. In the next two sections we introduce the model of coupled cavities of our interest (Section 2) and the quantities we are going to address, namely the energy gaps, and the staggered number-number correlations (Section 3). In Section 4 we discuss the zero-temperature equilibrium phase diagram, focusing on the MI/SF boundary and on the boundary separating the DW from the other phases. Finally, in Section 5 we draw our conclusions.\n\n## The model\n\nLet us consider a 1D array of QED cavities, where photons can hop between neighboring cavities. Moreover two adjacent resonators are also nonlinearly coupled to each other via a N-type four-level system, as shown in Figure 1(a). For the sake of clarity in our description, we shall divide the 1D array into coupled effective sites composed of a cavity and an atom. The four levels are denoted by $$\\{ \\vert i \\rangle \\}_{i = 1 ,\\ldots,4}$$, and are depicted in Figure 1(b). An external laser with frequency Ω resonantly drives the transition $$\\vert 3 \\rangle \\leftrightarrow \\vert 2 \\rangle$$. The transition $$\\vert 1 \\rangle \\leftrightarrow \\vert 3 \\rangle$$ is resonantly coupled to the cavity mode of the same site with strength $$g_{1}$$, while the transition $$\\vert 2 \\rangle \\leftrightarrow \\vert 4 \\rangle$$ couples to the cavity mode of its right nearest-neighbor site with strength $$g_{2}$$, and a detuning Δ.\n\nThe use of such N-type atom for generating large Kerr nonlinearity has been extensively studied in the literature [7, 8, 49], however the vast majority of the scenarios only focused on a single-mode cavity. Our work is inspired by the idea of Ref. , where the cross-Kerr nonlinearity is generated between two different and neighboring cavities, in circuit-QED systems. In practice, we use the unbalanced couplings of atomic transition $$|1\\rangle\\leftrightarrow|3\\rangle$$ with left cavity mode, and $$|2\\rangle\\leftrightarrow|4\\rangle$$ with right cavity mode respectively, in order to generate the local ($$g_{1}$$) and nonlocal ($$g_{2}$$) nonlinearities of our many-body system. This kind of four-level artificial molecule can be realized using two Josephson transmon qubits coupled by a superconducting quantum interference device.\n\nUsing the interaction picture and in the rotating-wave approximation, the system Hamiltonian reads\n\n$$\\mathcal{H}= \\sum_{i} \\bigl[ \\Delta\\sigma^{44}_{i} + \\bigl( \\Omega\\sigma^{23}_{i} + g_{1} \\sigma_{i}^{13} a_{i}^{\\dagger}+ \\mathrm{H.c.} \\bigr) + \\bigl(-t a_{i} a_{i+1}^{\\dagger}+ g_{2} \\sigma_{i}^{24} a_{i+1}^{\\dagger}+ \\mathrm{H.c.} \\bigr) \\bigr] ,$$\n(1)\n\nwhere $$\\sigma^{mn} = \\vert m \\rangle \\langle n\\vert$$ ($$m,n = 1,2,3,4$$), and a ($$a^{\\dagger}$$) is the annihilation (creation) operator of the cavity mode. The subscripts denote the site position along the 1D chain. The first three terms in the r.h.s. of Eq. (1) describe the local terms and the nonlinearities on each site. Inside the latter brackets, the first term is the photon hopping, while the second term describes the coupling of the atom to its right neighboring cavity, which generates an effective nonlocal cross-Kerr nonlinearity between the two cavities.\n\nHereafter we concentrate on the 1D model in Eq. (1) at zero temperature, specifically addressing the case without dissipation with DMRG. Let us also fix the Hamiltonian quantities in units of Ω, set $$\\hbar= 1$$, and work with open boundary conditions. We recall that, in the presence of dissipation, the problem becomes much more difficult to be handled numerically.Footnote 1\n\nFor the system we are considering here, in the strong coupling regime atoms and photons cannot be considered as two separate entities. It is thus natural to investigate the phase diagram in terms of combined atomic/photonic modes, named polaritons. The polaritonic number operator on each site i, representing the number of local excitations, is defined as $$n^{\\mathrm{pol}}_{i}=2\\sigma_{i}^{44}+\\sigma^{33}_{i}+\\sigma ^{22}_{i}+a^{\\dagger}_{i}a_{i}$$. For the closed system described by the Hamiltonian (1), the total number $$N^{\\mathrm{pol}} = \\sum_{i} n^{\\mathrm{pol}}_{i}$$ of such polaritons is a conserved quantity. In the following we work in the canonical ensemble for polaritons, and focus on the integer filling situation.\n\n## Energy gaps and correlation functions\n\nThe different nature of the various phases is sensitive to a number of properties which we are going to focus on. Here we are going to study quantities that resemble those characterizing the various phases of the EBH model .\n\nFirst of all, the ground-state energy gap is an important indicator which characterizes the presence or absence of criticality in the model. In particular, in the critical SF phase, the charge gap vanishes in the thermodynamic limit. On the other side, in the insulating MI and DW phases, such gap remains finite. In order to make connection with a similar notation in the EBH model, below we introduce the so called charge and neutral gaps referring respectively to the gaps corresponding to adding one extra particle (‘charge’ sector) or remaining with the same number of particles (‘neutral’ sector). We stress however that in the present model the excitation carry no real charge. This has to be understood only as a convention.\n\nThe charge gap is defined as\n\n$$\\Delta E_{c} = \\Delta E^{+} - \\Delta E^{-} ,$$\n(2)\n\nwhere, in the canonical ensemble, $$\\Delta E^{+}$$ ($$\\Delta E^{-}$$) denotes the extra energy needed to add (remove) one particle, i.e. one polariton, in the system. In the specific, focusing on the unit filling, $$\\Delta E^{+} = E_{L+1}-E_{L}$$ and $$\\Delta E^{-} = E_{L}-E_{L-1}$$, where $$E_{L}$$ is the ground-state energy per site of an L-sites cavity-array with exactly L excitations, and $$E_{L+1}$$ ($$E_{L-1}$$) is the corresponding energy per site with one excitation more (less). It is therefore possible to extrapolate $$\\Delta E_{c}$$ by running three different DMRG simulations with fixed number of polaritons $$N^{\\mathrm{pol}} = L-1, L, L+1$$ [52, 53].\n\nWhile the charge gap is able to detect particle-hole excitations, in some circumstances it is possible that the dominant low-energy excitations are of a different type. Their presence can be detected only by the so called neutral gap at a fixed number of particles,\n\n$$\\Delta E_{n} = E_{L}^{1} - E_{L} ,$$\n(3)\n\nwhere, again working in the canonical ensemble, $$E_{L}^{1}$$ denotes the first excited energy per site of an L-site system with L excitations.\n\nIn the following, we also focus on the analysis of the staggered diagonal order for the polaritons, in order to distinguish the DW from the other phases. We do this by investigating the two-point correlation function\n\n$$C_{\\mathrm{DW}}(r)=(-1)^{r} \\bigl\\langle \\delta n_{i}^{\\mathrm{pol}} \\delta n_{i+r}^{\\mathrm{pol}} \\bigr\\rangle ,$$\n(4)\n\nwhere $$\\delta n_{i}^{\\mathrm{pol}} = n^{\\mathrm{pol}}_{i}-\\bar{n}$$ denotes the polariton fluctuation from the average filling $$\\bar{n}$$. The order parameter identifying the DW phase is thus given by: $$\\mathcal{O}_{\\mathrm{DW}}\\equiv\\lim_{r\\rightarrow\\infty }{C_{\\mathrm{DW}}(r)}$$. A finite value of $$\\mathcal{O}_{\\mathrm{DW}}$$ indicates a tendency to establish, in the thermodynamic limit, a staggered occupation of the polaritons. On the other side, in the MI as well as the SF phases, $$C_{\\mathrm{DW}}(r)$$ vanishes exponentially with increasing distance r.\n\n## Phase diagram\n\nThe zero-temperature phase diagram of model (1), at unit polariton filling $$\\bar{n} = 1$$ and in the $$g_{2}-t$$ plane, is summarized in Figure 2. We observe that three different phases can be stabilized. Their boundaries have been obtained by means of a finite-size scaling of the numerical data, for systems up to $$L=300$$ sites. In our simulations we imposed a cutoff photon number in each cavity, such that $$n^{\\mathrm{phot}}_{i} \\leq3$$. We also truncated the effective Hilbert space dimension to a value $$m=80$$ in all the simulations, except for those shown in Figure 6 for the neutral energy gap (see the discussion in Section 4.3). We checked that, by increasing m and the local fock-space truncation over the photon number, the results concerning the charge gap and the DW order parameter do not change on the scales shown here.\n\nFor small photon hopping ($$t / \\Omega\\lessapprox0.2$$), by increasing the nonlocal nonlinearity $$g_{2}$$ the system exhibits a direct transition from the MI to the DW phase. On the other hand, for $$t / \\Omega\\gtrapprox0.2$$, the MI-to-DW transition is mediated by an extended region appearing at intermediate $$g_{2}$$ values, where the system stabilizes into a gapless SF. In the following we are going to elucidate our finite-size scaling procedure and how we were able to distinguish between the different phases.\n\n### Boundary between MI and SF phases\n\nIn the limit of small $$g_{2}$$ and t values, the dominant presence of the on-site interactions stabilize the system into a MI phase with exactly one polariton per cavity ($$\\bar{n} = 1$$), and where the charge energy gap has a finite value. As long as the hopping strength t is progressively increased (and for fixed $$g_{1}$$, $$g_{2}$$), the system eventually enters a SF phase, with a vanishing gap. The filled squares of Figure 2 denoting the MI/SF boundaries have been obtained by means of a finite-size scaling of the charge gap. We performed simulations up to $$L=100$$ sites and analyzed whether the gap closes or remains finite in the thermodynamic limit $$L \\to\\infty$$.\n\nIn Figure 3, left panel, we highlight the size-dependence of $$\\Delta E_{c}$$ as a function of $$1/L$$ for two points in the phase space close to the MI/SF transition (see points along the dotted line in Figure 2). We expect to see a quadratic dependence $$\\Delta E_{c} \\sim L^{-2}$$ (dashed line) at large L [52, 53], however a linear extrapolation (solid line) is already a good approximation to the scaling, and we can use it to determine $$\\Delta E_{c}$$ in the thermodynamics limit. Indeed, we observe that the difference between quadratic and linear extrapolation is tiny (10−3) and does not produce any distinguishable modification on the scale of Figure 2. In the specific case of Figure 3, we fixed $$t / \\Omega= 0.25$$ and chose two different values of $$g_{2} / \\Omega$$ corresponding to configurations in the gapped MI ($$g_{2} / \\Omega= 1.35$$, triangles) and in the gapless SF phase ($$g_{2} / \\Omega= 1.5$$, squares). The MI is signaled by an extrapolated finite value of $$\\lim_{L \\to \\infty} \\Delta E_{c} > 0$$, while in the SF this is zero.\n\nIn order to locate the critical $$g_{2}$$ for a given value of t (filled squares in Figure 2) we perform a linear extrapolation of the charge gaps in the vicinity of the critical value of $$g_{2}$$. An example of such procedure is shown in the right panel of Figure 3, where we plot $$\\Delta E_{c}$$ as a function of $$g_{2}$$, when this is close to the phase transition (in the specific, here we set $$t / \\Omega= 0.25$$). After a linear extrapolation, we get a critical $$g_{2}$$ value corresponding to $$g_{2}^{*} / \\Omega\\approx1.379$$. An analogous procedure is repeated for all the filled squares shown in Figure 2, thus identifying the MI/SF boundary.\n\n### Boundary of the DW phase\n\nThe DW phase is characterized by a finite order parameter $${\\mathcal{O}}_{\\mathrm{DW}}$$. Let us therefore look at the two-point staggered correlator in Eq. (4). Since in DMRG simulations we are employing open boundary conditions, to minimize the border effects we analyze the correlations in such a way that the two points are taken symmetrically with respect to the center of the system.Footnote 2 The left panel of Figure 4 shows how differently such polariton correlations behave when the system goes from the MI to DW phase, for a fixed system size.\n\nTo be more accurate, in the right panel we performed a finite-size scaling and showed that the staggered correlation $$C_{\\mathrm{DW}}(r)$$ approaches the zero value exponentially with L, in the MI phase (a similar behavior occurs in the SF region). On the other hand, in the DW such correlator asymptotically converges to a finite value. In the specific, here we fix $$t/\\Omega=0.05$$ and show that for $$g_{2}/\\Omega= 1.3, 1.35$$ the DW order is exponentially suppressed with L, while for $$g_{2}/\\Omega= 1.4$$ it remains finite. The $${\\mathcal{O}}_{\\mathrm{DW}}$$ order parameter reached for $$L \\to \\infty$$ is displayed in the inset as a function of $$g_{2}$$.\n\nIn order to determine the DW boundary in the phase diagram of Figure 2, we adopted the following protocol. For a fixed value of $$t/\\Omega$$, we start increasing $$g_{2}$$ from zero up to a finite value, with a fixed increment $$\\delta g_{2} = 0.05 \\Omega$$, and to compute the DW order parameter for all such values of $$g_{2}$$. The boundary of DW phase in the $$g_{2}-t$$ plane (filled circles in Figure 2), for any fixed t, is located by the $$g_{2}^{*}(t)$$ that gives the first non-vanishing order parameter $$\\mathcal{O}_{\\mathrm{DW}}$$.\n\nHere we stress that, because of the arrangement of our 1D array [see Figure 1(a)] and of the asymmetric coupling between the atom and its right/left cavity, the antiferromagnetic symmetry of the system is spontaneously broken. In particular, the state $$\\vert 4 \\rangle$$ of the L-th atom will be never occupied, since the transition $$\\vert 2 \\rangle \\leftrightarrow \\vert 4 \\rangle$$ does not couple to any cavity mode [see Eq. (1)]. As a consequence, in our simulations we do not need any symmetry-breaking potential. We can observe that the expectation value for the onsite number of polaritons explicitly exhibits a staggered behavior, in that the occupation of the $$(2n-1)$$-th site is always higher than that of the $$(2n)$$-th site (for any integer value of n). Finally we notice that such staggering persists at finite size, also for the set of parameters corresponding to the MI phase, although it is extremely tiny and decreases with L. This effect eventually disappears in the thermodynamic limit.\n\nThe extension of the DW phase depends on the cavity detuning Δ. In particular, the robustness of the order parameter increases with increasing the modulus of the detuning (see Figure 5). Quite remarkably, we note that a positive Δ will never stabilize an antiferromagnetic DW ordering.\n\n### Neutral gap\n\nThe analysis leading to the phase diagram in Figure 2 has been corroborated by a study of the neutral gap, which vanishes both in proximity of the phase transitions and in the entire superfluid region. Differently for the charge gap, it is able to detect the presence of excitations other than particle-hole, and thus locates the boundaries of insulating regions (as the DW) beyond the MI.\n\nThe data displayed in Figure 6 show the behavior of $$\\Delta E_{n}$$ as a function of $$g_{2}$$, for a fixed value of $$t / \\Omega$$. In particular we analyzed a vertical cut in the phase diagram of Figure 2 (see the rightmost vertical dotted line in that figure), where the system can be in three different phases according to the value of $$g_{2}$$. With increasing $$g_{2}$$, it goes from the MI phase (nonzero $$\\Delta E_{n}$$, for $$t/\\Omega\\lesssim1.45$$) to the SF phase (zero $$\\Delta E_{n}$$, for $$1.45 \\lesssim t/\\Omega \\lesssim1.8$$), and then to the DW phase (nonzero $$\\Delta E_{n}$$, for $$t/\\Omega\\gtrsim1.8$$).\n\nWhile we cannot see a clear signature of a finite gap for $$g_{2} = 1.8 \\Omega$$, the scaling with the size displayed in the left panel of Figure 6 seems to suggest the scenario depicted above. It is however important to stress that the DMRG simulations needed to compute the neutral gap have to target the two lowest-lying eigenstates in a single run. Thus they generally require a larger dimension m of the effective Hilbert space, as compared to all the other ground-state calculations discussed before. The analysis of the neutral gap requires a careful convergence test of the results with m, which we provide in the right panel of Figure 6. We observe that the non monotonic features that are visible in the region $$1.45 \\lesssim t/\\Omega\\lesssim1.8$$ have to be probably ascribed to the inaccuracy of the method at small m values. This signals the presence of the gapless SF phase there, in agreement with the results provided by the charge gap (MI/SF boundary) and for the DW order parameter (SF/DW boundary).\n\n## Summary\n\nUsing the density-matrix renormalization group with open boundary conditions, we studied the equilibrium phase diagram of a system of coupled QED cavities in one dimension. We provided results beyond the standard model of couplings through photon hopping, and also considered nearest-neighbor cross-Kerr nonlinearities. Our analysis is based on a finite-size scaling of the ground-state charge and neutral gaps, as well as of the density-wave order parameter, for systems up to 300 sites. We showed that, beyond the conventional Mott insulator and superfluid phases, the presence of a nearest-neighbor nonlinear coupling can also stabilize a density-wave ordering of polaritons.\n\n1. 1.\n\nIt is however possible to address the effect of dissipation with a DMRG approach in a 1D chain, when this is described by a master equation within the Lindblad formalism. In the language of tensor networks, one has to generalize the matrix-product-state ansatz to a matrix-product-density-operator ansatz for mixed states, as originally proposed in Refs. [50, 51]. The computational complexity is greater than for static computations, and is eventually related to the amount of entanglement in the steady state.\n\n2. 2.\n\nThe two points of $$\\langle\\delta n_{i}^{\\mathrm{pol}} \\delta n_{j}^{\\mathrm{pol}} \\rangle$$, with $$\\vert i - j\\vert = r$$, have been chosen such that $$i = (L - r + 1)/2$$, $$j = (L + r + 1)/2$$ for odd r, and $$i = (L - r)/2$$, $$j = (L + r)/2$$ for even r (e.g. for $$L = 100$$ sites, $$r = 1$$ corresponds to $$i = 50$$, $$j = 51$$; $$r = 2$$ corresponds to $$i = 49$$, $$j = 51$$; $$r = 3$$ to $$i = 49$$, $$j = 52$$, and so on).\n\n## References\n\n1. 1.\n\nBloch I, Dalibard J, Zwerger W. Many-body physics with ultracold gases. Rev Mod Phys. 2008;80:885.\n\n2. 2.\n\nFisher MPA, Weichman PB, Grinstein G, Fisher DS. Boson localization and the superfluid-insulator transition. Phys Rev B. 1989;40:546.\n\n3. 3.\n\nJaksch D, Bruder C, Cirac JI, Gardiner CW, Zoller P. Cold bosonic atoms in optical lattices. Phys Rev Lett. 1998;81:3108.\n\n4. 4.\n\nGreiner M, Mandel O, Esslinger T, Hänsch TW, Bloch I. Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms. Nature. 2002;415:39.\n\n5. 5.\n\nLewenstein M, Sanpera A, Ahufinger V, Damski B, Sen(De) A, Sen U. Ultracold atomic gases in optical lattices: mimicking condensed matter physics and beyond. Adv Phys. 2007;56:243.\n\n6. 6.\n\nLahaye T, Menotti C, Santos L, Lewenstein M, Pfau T. The physics of dipolar bosonic quantum gases. Rep Prog Phys. 2009;72:126401.\n\n7. 7.\n\nSchmidt H, Imamoǧlu A. Giant Kerr nonlinearities obtained by electromagnetically induced transparency. Opt Lett. 1996;21:1936.\n\n8. 8.\n\nImamoǧlu A, Schmidt H, Woods G, Deutsch M. Strongly interacting photons in a nonlinear cavity. Phys Rev Lett. 1997;79:1467.\n\n9. 9.\n\nHartmann MJ, Brandão FGSL, Plenio MB. Strongly interacting polaritons in coupled arrays of cavities. Nat Phys. 2006;2:849.\n\n10. 10.\n\nGreentree AD, Tahan C, Cole JH, Hollenberg LCL. Quantum phase transitions of light. Nat Phys. 2006;2:856.\n\n11. 11.\n\nAngelakis DG, Santos MF, Bose S. Photon-blockade-induced Mott transitions and XY spin models in coupled cavity arrays. Phys Rev A. 2007;76:031805(R).\n\n12. 12.\n\nHartmann MJ, Brandão FGSL, Plenio MB. Quantum many-body phenomena in coupled cavity arrays. Laser Photonics Rev. 2008;2:527.\n\n13. 13.\n\nTomadin A, Fazio R. Many-body phenomena in QED-cavity arrays. J Opt Soc Am. 2010;27:A130.\n\n14. 14.\n\nHouck AA, Türeci HE, Koch J. On-chip quantum simulation with superconducting circuits. Nat Phys. 2012;8:292.\n\n15. 15.\n\nSchmidt S, Koch J. Circuit QED lattices: towards quantum simulation with superconducting circuits. Ann Phys. 2013;525:395.\n\n16. 16.\n\nCarusotto I, Gerace D, De Liberato S, Ciuti C, Imamoǧlu A. Fermionized photons in an array of driven dissipative nonlinear cavities. Phys Rev Lett. 2009;103:033601.\n\n17. 17.\n\nTomadin A, Giovannetti V, Fazio R, Gerace D, Carusotto I, Türeci HE, Imamoǧlu A. Signatures of the superfluid-insulator phase transition in laser-driven dissipative nonlinear cavity arrays. Phys Rev A. 2010;81:061801(R).\n\n18. 18.\n\nHartmann MJ. Polariton crystallization in driven arrays of lossy nonlinear resonators. Phys Rev Lett. 2010;104:113601.\n\n19. 19.\n\nNunnenkamp A, Koch J, Girvin SM. Synthetic gauge fields and homodyne transmission in Jaynes-Cummings lattices. New J Phys. 2011;13:095008.\n\n20. 20.\n\nNissen F, Schmidt S, Biondi M, Blatter G, Türeci HE, Keeling J. Nonequilibrium dynamics of coupled qubit-cavity arrays. Phys Rev Lett. 2012;108:233603.\n\n21. 21.\n\nGrujic T, Clark SR, Angelakis DG, Jaksch D. Non-equilibrium many-body effects in driven nonlinear resonator arrays. New J Phys. 2012;14:103025.\n\n22. 22.\n\nGrujic T, Clark SR, Jaksch D, Angelakis DG. Repulsively induced photon superbunching in driven resonator arrays. Phys Rev A. 2013;87:053846.\n\n23. 23.\n\nJin J, Rossini D, Fazio R, Leib M, Hartmann MJ. Photon solid phases in driven arrays of nonlinearly coupled cavities. Phys Rev Lett. 2013;110:163605.\n\n24. 24.\n\nJin J, Rossini D, Leib M, Hartmann MJ, Fazio R. Steady-state phase diagram of a driven QED-cavity array with cross-Kerr nonlinearities. Phys Rev A. 2014;90:023827.\n\n25. 25.\n\nUnderwood DL, Shanks WE, Koch J, Houck AA. Low-disorder microwave cavity lattices for quantum simulation with photons. Phys Rev A. 2012;86:023837.\n\n26. 26.\n\nAbbarchi M, Amo A, Sala VG, Solnyshkov DD, Flayac H, Ferrier L, Sagnes I, Galopin E, Lemaître A, Malpuech G, Bloch J. Macroscopic quantum self-trapping and Josephson oscillations of exciton polaritons. Nat Phys. 2013;9:275.\n\n27. 27.\n\nToyoda K, Matsuno Y, Noguchi A, Haze S, Urabe S. Experimental realization of a quantum phase transition of polaritonic excitations. Phys Rev Lett. 2013;111:160501.\n\n28. 28.\n\nLucero E, Barends R, Chen Y, Kelly J, Mariantoni M, Megrant A, O’Malley P, Sank D, Vainsencher A, Wenner J, White T, Yin Y, Cleland AN, Martinis JM. Computing prime factors with a Josephson phase qubit quantum processor. Nat Phys. 2012;8:719.\n\n29. 29.\n\nSteffen L, Salathe Y, Oppliger M, Kurpiers P, Baur M, Lang C, Eichler C, Puebla-Hellmann G, Fedorov A, Wallraff A. Deterministic quantum teleportation with feed-forward in a solid state system. Nature. 2013;500:319.\n\n30. 30.\n\nChen Y, Roushan P, Sank D, Neill C, Lucero E, Mariantoni M, Barends R, Chiaro B, Kelly J, Megrant A, Mutus JY, O’Malley PJJ, Vainsencher A, Wenner J, White TC, Yin Y, Cleland AN, Martinis JM. Emulating weak localization using a solid-state quantum circuit. Nat Commun. 2014;5:5184.\n\n31. 31.\n\nZueco D, Mazo JJ, Solano E, García Ripoll JJ. Microwave photonics with Josephson junction arrays: negative refraction index and entanglement through disorder. Phys Rev B. 2012;86:024503.\n\n32. 32.\n\nPeropadre B, Zueco D, Wulschner F, Deppe F, Marx A, Gross R, García Ripoll JJ. Tunable coupling engineering between superconducting resonators: from sidebands to effective gauge fields. Phys Rev B. 2013;87:134504.\n\n33. 33.\n\nSowiński T, Dutta O, Hauke P, Tagliacozzo L, Lewenstein M. Dipolar molecules in optical lattices. Phys Rev Lett. 2012;108:115301.\n\n34. 34.\n\nDalla Torre EG, Berg E, Altman E. Hidden order in 1D Bose insulators. Phys Rev Lett. 2006;97:260401.\n\n35. 35.\n\nBerg E, Dalla Torre EG, Giamarchi T, Altman E. Rise and fall of hidden string order of lattice bosons. Phys Rev B. 2008;77:245119.\n\n36. 36.\n\nRossini D, Fazio R. Phase diagram of the extended Bose-Hubbard model. New J Phys. 2012;14:065012.\n\n37. 37.\n\nDeng X, Citro R, Orignac E, Minguzzi A, Santos L. Polar bosons in one-dimensional disordered optical lattices. Phys Rev B. 2013;87:195101.\n\n38. 38.\n\nWikberg E, Larson J, Bergholtz EJ, Karlhede A. Fractional domain walls from on-site softening in dipolar bosons. Phys Rev A. 2012;85:033607.\n\n39. 39.\n\nBatrouni GG, Scalettar RT, Rousseau VG, Grémaud B. Competing supersolid and Haldane insulator phases in the extended one-dimensional bosonic Hubbard model. Phys Rev Lett. 2013;110:265303.\n\n40. 40.\n\nBatrouni GG, Rousseau VG, Scalettar RT, Grémaud B. Competing phases, phase separation, and coexistence in the extended one-dimensional bosonic Hubbard model. Phys Rev B. 2014;90:205123.\n\n41. 41.\n\nSchiró M, Bordyuh M, Öztop B, Türeci HE. Phase transition of light in cavity QED lattices. Phys Rev Lett. 2012;109:053601.\n\n42. 42.\n\nKumar B, Jalal S. Quantum Ising dynamics and Majorana-like edge modes in the Rabi lattice model. Phys Rev A. 2013;88:011802(R).\n\n43. 43.\n\nSchollwöck U. The density-matrix renormalization group. Rev Mod Phys. 2005;77:259.\n\n44. 44.\n\nDe Chiara G, Rizzi M, Rossini D, Montangero S. Density matrix renormalization group for dummies. J Comput Theor Nanosci. 2008;5:1277.\n\n45. 45.\n\nRossini D, Fazio R. Mott-insulating and glassy phases of polaritons in 1D arrays of coupled cavities. Phys Rev Lett. 2007;99:186401.\n\n46. 46.\n\nRossini D, Santoro GE, Fazio R. Photon and polariton fluctuations in arrays of QED-cavities. Europhys Lett. 2008;83:47011.\n\n47. 47.\n\nD’Souza AG, Sanders BC, Feder DL. Fermionized photons in the ground state of one-dimensional coupled cavities. Phys Rev A. 2013;88:063801.\n\n48. 48.\n\nHu Y, Ge GQ, Chen S, Yang XF, Chen YL. Cross-Kerr-effect induced by coupled Josephson qubits in circuit quantum electrodynamics. Phys Rev A. 2011;84:012329.\n\n49. 49.\n\nRebić S, Twamley J, Milburn GJ. Giant Kerr nonlinearities in circuit quantum electrodynamics. Phys Rev Lett. 2009;103:150503.\n\n50. 50.\n\nVerstraete F, García-Ripoll JJ, Cirac JI. Matrix product density operators: simulation of finite-temperature and dissipative systems. Phys Rev Lett. 2004;93:207204.\n\n51. 51.\n\nZwolak M, Vidal G. Mixed-state dynamics in one-dimensional quantum lattice systems: a time-dependent superoperator renormalization algorithm. Phys Rev Lett. 2004;93:207205.\n\n52. 52.\n\nKühner TD, Monien H. Phases of the one-dimensional Bose-Hubbard model. Phys Rev B. 1998;58:R14741.\n\n53. 53.\n\nKühner TD, White SR, Monien H. One-dimensional Bose-Hubbard model with nearest-neighbor interaction. Phys Rev B. 2000;61:12474.\n\n## Acknowledgements\n\nWe would like to acknowledge our previous collaboration with M. Hartmann and M. Leib which was inspiring for the present work. This work was supported by Italian MIUR via FIRB Project RBFR12NLNA and PRIN Project 2010LLKJBX, by EU through IP-SIQS, and by National Natural Science Foundation of China under Grant No. 11175033 and No. 11305021.\n\n## Author information\n\nCorrespondence to Jiasen Jin.\n\n### Competing interests\n\nThe authors declare that they have no competing interests.\n\n### Authors’ contributions\n\nAll the authors participated in the design of the research, analysis of the results, and writing of the paper. The DMRG code used to run all the simulations of this research has been developed and written by DR and coworkers (see also www.dmrg.it). The DMRG simulations were performed by JJ.\n\n## Rights and permissions\n\nOpen Access This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.\n\nReprints and Permissions",
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http://drorbn.net/dbnvp/LD15_Kuno-1.php | [
"© | Dror Bar-Natan: Talks: LesDiablerets-1508: < >\n\n# Kuno's Talk 1\n\n width: 400 720 1280 download ogg/LD15_Kuno-1_400.ogg For now, this video can only be viewed with web browsers that support\n\nNotes on LD15_Kuno-1: [edit, refresh]\n\nrefresh\npanel\nManaged by dbnvp: The small-font numbers on the top left of the videos indicate the available native resolutions. Click to test.",
null,
"0:05:35 The mapping class group and $\\pi_1$.",
null,
"0:09:25 The Johnson filtration.",
null,
"0:12:50 The Johnson filtration, 2.",
null,
"0:14:50 The Johnson homomorphism. In the Artin case, this is the action of the Drinfel'd-Kohno Lie algebra on the free Lie algebra.",
null,
"0:19:35 A geometric construction.",
null,
"0:22:55 This seems to be the theorem on page 7 of Kawazumi's notes. The completion $\\widehat{{\\mathbb Q}\\pi}$ is relative to powers $(I\\pi)^p$ of the augmentation ideal. The completion $\\widehat{{\\mathbb Q}\\hat\\pi}$ is relative to ${\\mathbb Q}{\\mathbb 1}+|(I\\pi)^p|$.",
null,
"0:23:18 According to page 8 of Kawazumi's notes, $\\tau$ is related to the Massuyeau Johnson map.",
null,
"0:25:34 $\\tau$ and simple closed curves.",
null,
"0:31:06 $\\tau(t_C) = L(C) = \\left|\\frac12(\\log x)^2\\right|$",
null,
"0:34:32 Proof of $\\tau(t_C) = L(C) = \\left|\\frac12(\\log x)^2\\right|$.",
null,
"0:38:03 Generalized Dehn twists.",
null,
"0:42:52 Given a symplectic expansion $\\theta$...",
null,
"0:48:00 $\\delta\\circ\\tau=0$.",
null,
"0:50:55 $\\delta\\circ\\tau=0$, part II. What's the geometry behind this?",
null,
"0:57:52 Is there $\\theta$ such that $\\delta^\\theta=\\delta^{alg}$?"
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https://web2.0calc.com/questions/in-how-many-different-ways-can-2-15-be-represented | [
"+0\n\nIn how many different ways can 2/15 be represented as 1/a + 1/b, if a and b are positive integers with a>b\n\n+1\n245\n2\n\nIn how many different ways can 2/15 be represented as 1/A + 1/B, if A and B are positive integers with A less than or equal to B\n\nJan 21, 2019\nedited by Guest Jan 21, 2019\n\n#1\n+1\n\nIs this what you mean?\n\n1/8 + 1 / 120 = 2/15\n1/9 + 1 / 45 = 2/15\n1/10 + 1 / 30 = 2/15\n1/12 + 1 / 20 = 2/15\n\n1/15 + 1/15 = 2/15\n\nJan 22, 2019\nedited by Guest Jan 22, 2019\n#2\n+8\n\nIn how many different ways can 2/15 be represented as 1/A + 1/B,\n\nif A and B are positive integers with A less than or equal to B\n\n$$\\text{For odd n>2 there is always at least one decomposition into exactly two unit fractions: \\dfrac{2}{n} = \\dfrac{1}{A} + \\dfrac{1}{B} } \\\\ \\text{Finding all possibilities.}\\\\ \\text{The prime factorization of n^2 results in all possible decompositions into two unit fractions.}$$\n\n$$n=15\\ \\text{is odd} \\\\ n^2 =225 \\\\ \\text{All divisors of n^2=225 are: 1,\\ 3,\\ 5,\\ 9,\\ 15,\\ 25,\\ 45,\\ 75,\\ 225}\\\\ \\text{Let n^2=p\\times q }$$\n\n$$\\begin{array}{|r|r|r|c|c|c|c|c|c|c|c|c| } \\hline & p & q & n^2 & s & t & r & k & A & B & A\\le B & \\\\ & & & =p\\cdot q & = \\frac{p+q}{2} & = \\frac{p-q}{2} & =\\frac{t}{2} & = \\frac{15+\\sqrt{15^2+t^2} }{2} & =k-r & =k+r & \\\\ \\hline 1. & 225 & 1 & 225=225 \\cdot 1 & 113 & 112 & 56 & 64 & 8 & 120 & \\checkmark & \\mathbf{\\dfrac{2}{15} = \\dfrac{1}{8} + \\dfrac{1}{120}} \\\\ \\hline 2. & 75 & 3 & 225= 73 \\cdot 3 & 39 & 36 & 18 & 27 & 9 & 45 & \\checkmark & \\mathbf{\\dfrac{2}{15} = \\dfrac{1}{9} + \\dfrac{1}{45}} \\\\ \\hline 3. & 45 & 5 & 225= 45 \\cdot 5 & 25 & 20 & 10 & 20 & 10 & 30 & \\checkmark & \\mathbf{\\dfrac{2}{15} = \\dfrac{1}{10} + \\dfrac{1}{30}} \\\\ \\hline 4. & 25 & 9 & 225= 25 \\cdot 9 & 17 & 8 & 4 & 16 & 12 & 20 & \\checkmark & \\mathbf{\\dfrac{2}{15} = \\dfrac{1}{12} + \\dfrac{1}{20}} \\\\ \\hline 5. & 15 & 15 & 225= 15 \\cdot 15 & 15 & 0 & 0 & 15 & 15 & 15 & \\checkmark & \\mathbf{\\dfrac{2}{15} = \\dfrac{1}{15} + \\dfrac{1}{15}} \\\\ \\hline \\end{array}$$",
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"Jan 22, 2019\nedited by heureka Jan 22, 2019\nedited by heureka Jan 22, 2019"
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"https://web2.0calc.com/img/emoticons/smiley-laughing.gif",
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.5429228,"math_prob":0.9999355,"size":1765,"snap":"2019-43-2019-47","text_gpt3_token_len":829,"char_repetition_ratio":0.15388983,"word_repetition_ratio":0.1589041,"special_character_ratio":0.5858357,"punctuation_ratio":0.053333335,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9987674,"pos_list":[0,1,2],"im_url_duplicate_count":[null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-10-14T14:20:34Z\",\"WARC-Record-ID\":\"<urn:uuid:cf3f1b24-6f85-4dea-912c-19556981f7f6>\",\"Content-Length\":\"25359\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:dad4f558-44e7-4af9-a2a7-7ada22502b40>\",\"WARC-Concurrent-To\":\"<urn:uuid:ce3e970b-4363-4f9e-bdad-cfa5e836059f>\",\"WARC-IP-Address\":\"144.76.186.3\",\"WARC-Target-URI\":\"https://web2.0calc.com/questions/in-how-many-different-ways-can-2-15-be-represented\",\"WARC-Payload-Digest\":\"sha1:INR6HDJIFAEQF7HR6DXSYF7HOUNYOBQO\",\"WARC-Block-Digest\":\"sha1:CB3O6YEQFKZSPI7Q3KO3PQZVQHFEZWCF\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-43/CC-MAIN-2019-43_segments_1570986653247.25_warc_CC-MAIN-20191014124230-20191014151730-00507.warc.gz\"}"} |
https://pennstate.pure.elsevier.com/en/publications/improved-bounds-for-the-nystr%C3%B6m-method-with-application-to-kernel | [
"# Improved bounds for the nyström method with application to kernel classification\n\nRong Jin, Tianbao Yang, Mehrdad Mahdavi, Yu Feng Li, Zhi Hua Zhou\n\nResearch output: Contribution to journalArticlepeer-review\n\n25 Citations (SciVal)\n\n## Abstract\n\nWe develop two approaches for analyzing the approximation error bound for the Nyström method that approximates a positive semidefinite (PSD) matrix by sampling a small set of columns, one based on a concentration inequality for integral operators, and one based on random matrix theory. We show that the approximation error, measured in the spectral norm, can be improved from O(N/√ m) to O(N/m1-1) in the case of large eigengap, where N is the total number of data points, m is the number of sampled data points, and \\rho \\in (0, 1/2) is a positive constant that characterizes the eigengap. When the eigenvalues of the kernel matrix follow a p-power law, our analysis based on random matrix theory further improves the bound to O(N/mp-1) under an incoherence assumption. We present a kernel classification approach based on the Nyström method and derive its generalization performance using the improved bound. We show that when the eigenvalues of the kernel matrix follow a p-power law, we can reduce the number of support vectors to N2p/(p2-1) which is sublinear in N when p > 1+√2, without seriously sacrificing its generalization performance.\n\nOriginal language English (US) 6547995 6939-6949 11 IEEE Transactions on Information Theory 59 10 https://doi.org/10.1109/TIT.2013.2271378 Published - 2013\n\n## All Science Journal Classification (ASJC) codes\n\n• Information Systems\n• Computer Science Applications\n• Library and Information Sciences\n\n## Fingerprint\n\nDive into the research topics of 'Improved bounds for the nyström method with application to kernel classification'. Together they form a unique fingerprint."
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8451339,"math_prob":0.56983507,"size":1511,"snap":"2021-43-2021-49","text_gpt3_token_len":350,"char_repetition_ratio":0.1128069,"word_repetition_ratio":0.051948052,"special_character_ratio":0.22700198,"punctuation_ratio":0.06130268,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.95459753,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-12-01T14:00:27Z\",\"WARC-Record-ID\":\"<urn:uuid:f5627fa9-9a1e-4d0d-958f-e847d3e0983a>\",\"Content-Length\":\"46820\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:73266a66-ce39-428a-862b-043a228c2d82>\",\"WARC-Concurrent-To\":\"<urn:uuid:4ba65091-601d-42b3-8fe9-5048c8ca9bce>\",\"WARC-IP-Address\":\"3.90.122.189\",\"WARC-Target-URI\":\"https://pennstate.pure.elsevier.com/en/publications/improved-bounds-for-the-nystr%C3%B6m-method-with-application-to-kernel\",\"WARC-Payload-Digest\":\"sha1:22SAOJKGBAISIE2I624RKQ6TRLKPHB7G\",\"WARC-Block-Digest\":\"sha1:K3MD435ZZVRJ6GJPN7BQMFFZWTRRBIZR\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-49/CC-MAIN-2021-49_segments_1637964360803.0_warc_CC-MAIN-20211201113241-20211201143241-00085.warc.gz\"}"} |
https://arcadianfunctor.wordpress.com/2007/09/25/m-is-for-magic/ | [
"## M is for Magic\n\nAs we have seen, Carl Brannen’s QFT uses circulant matrices. By resetting a mass scale, one may renormalise a 1-circulant\n\nXYZ\nZXY\nYZX\n\nby a constant $\\lambda = \\frac{1}{Y + Z – 2X}$ so that the resulting circulant obeys the condition $2X = Y + Z$. This turns the circulant into a magic square. For 2-circulants the condition is instead $2Z = X + Y$. Although perhaps not a very useful observation, it is certainly entertaining! The total number of $5 \\times 5$ normal (ie. matrices built from the first few ordinals) magic squares was only computed in 1973, and the number of $6 \\times 6$ ones is still unknown. There is only one $3 \\times 3$ normal square, up to rotation and reflection.\n\nA paper by A. Adler uses circulants to find an algorithm for generating higher order normal magic n-cubes, by playing with p-adic L functions. For $p = 3$, Adler constructs two cute normal magic cubes: a $3 \\times 3 \\times 3$ cube and a $27 \\times 27 \\times 27$ cube. I was further intrigued by this paper of Adler’s, containing the conjecture that magic n-cubes always form a free monoid. It shows first that sets of magic squares contain prime squares, out of which all others are constructed, and then that generating functions built from cardinalities for magic cubes have the remarkable property of being everywhere divergent!\n\n## 2 Responses so far »\n\n1. 1",
null,
"### Matti Pitkanen said,\n\nThis monoid property of magic would be nice. The divergence of generating function as real function everywhere would mean that generating function for magic squares would exist as p-adic number for some p:s (probably very many). This would give additional strong support for the idea that p-adic generating functions are more natural than those with real argument.\n\n2. 2",
null,
"### Kea said,\n\nHi Matti. Unfortunately, as Adler writes and Google indicates, it appears that little research is being done on magic squares."
] | [
null,
"https://0.gravatar.com/avatar/",
null,
"https://0.gravatar.com/avatar/",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.9219846,"math_prob":0.9958174,"size":1900,"snap":"2021-43-2021-49","text_gpt3_token_len":468,"char_repetition_ratio":0.12447257,"word_repetition_ratio":0.0062305294,"special_character_ratio":0.24210526,"punctuation_ratio":0.10354223,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9808083,"pos_list":[0,1,2,3,4],"im_url_duplicate_count":[null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-10-24T15:26:21Z\",\"WARC-Record-ID\":\"<urn:uuid:96d518b8-b164-471c-99ec-27e32ffd13e3>\",\"Content-Length\":\"78343\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:6d555c49-277b-492c-8179-7125ce2e05dd>\",\"WARC-Concurrent-To\":\"<urn:uuid:a88a565f-7d2b-4a6a-a4b2-2760fc0f0b0e>\",\"WARC-IP-Address\":\"192.0.78.12\",\"WARC-Target-URI\":\"https://arcadianfunctor.wordpress.com/2007/09/25/m-is-for-magic/\",\"WARC-Payload-Digest\":\"sha1:DF4DXNZ5CUI6PJUOP5W6UHJKM5TYAC7Z\",\"WARC-Block-Digest\":\"sha1:KL5ITVLUICVDHDVI3NR6EEJVBXTZTE3G\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-43/CC-MAIN-2021-43_segments_1634323586043.75_warc_CC-MAIN-20211024142824-20211024172824-00008.warc.gz\"}"} |
https://financial-calculators.com/author/morris | [
"The Rule-of-78s : The Formula and How It Works\n\nOutside of banking circles, the Rule-of-78′s is little understood, even though it is commonly applied to many consumer and business loans. For the borrower, it tends to have a pernicious effect in the nature of a hidden prepayment penalty. The borrower’s disadvantage is heightened by the fact that the operation of the Rule-of-78′s is often referred to as a \"Rebate of the Finance Charge.\" Any consumer who heard the word \"rebate\" is always tempted to say, \"Where do I sign?\"\n\nNot so fast!\n\nHere’s how it works: The name comes from the sum of the numbers one through 12, there being 12 months in a year. Yes, that adds to 78.\n\nThe theory of the Rule-of-78′s is that at the moment a borrower signs the Note, the borrower is immediately obligated to pay back all of the principal and ALL of the interest that will accrue in the future over the agreed term of the loan.\n\nNow, if the borrower prepays, the lender \"generously\" forgives some of the interest EVEN THOUGH at the time for it to accrue has not yet elapsed and so that additional interest has not been earned. That’s the so-called \"Rebate.\" Lenders argue that the uncertainty created about an early payoff entitles them to some compensation for being at the borrower’s whim for payoff. In a time of falling interest rates, that argument may have more merit than when interest rates are rising as the lender gets to put the money back to work at a higher rate and earn more.\n\nIn any event, the Rebate is calculated by summing the number of payments elapsed in inverse order as a numerator for the fraction in which the sum of the term is the denominator. That fraction times all interest over the life of the loan is the amount earned by the lender.\n\nWatch this example:\n\nAssume a two-year loan (so we’ll assume the numbers 1 through 24) for \\$10,000 with interest at 12% per year. Using our online amortization schedule calculator, we know the monthly payment is \\$470.73. The amortization schedule’s \"Running Totals\" also tells us that over the life of the loan the total amount of aggregate interest to be paid would be \\$1,297.56 (when the \"1st payment date\" is one month after the \"loan date\").\n\nAfter the fourth month, our borrower reaps a windfall and wants to prepay the whole loan. The fraction of the total interest earned by the lender is:\n\n(Sum 24 to 21) over (Sum 1 through Sum 24)\n\n90/300 = 30%\n\nNow, let’s compare that to the interest actually paid to date to see what the penalty will be. From running the \"Loan Table\" module, we found the total interest to be \\$1,297.65 and the interest paid after four payments is \\$377.61, so the penalty is:\n\nEarned Interest Per Rule: (30%) (\\$1,297.65) = \\$389.30\n\nInterest Paid to Payoff: \\$377.61\n\nAdditional Interest Owed: \\$11.69\n\nMaybe that doesn’t look like too big a number, but it’s an additional 3.1% interest. Had this been a \\$100,000 loan, the increased penalty works out to ten times as much, \\$116.84.\n\nPaying off at different times for different maturities and different interest rates produces differing penalty sizes. Two general rules of thumb can be deduced:\n\n1. The higher the interest rate, the greater the penalty amount.\n\n2. The earlier the prepayment in relation to the term, the greater the penalty amount.\n\nSo if you’re a lender, you should love using the Rule-of-78′s. If you’re a borrower, you should try to avoid it. A caution for lenders: Some states have usury and other laws that may limit use of the Rule-of-78′s."
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.94582736,"math_prob":0.92328054,"size":3671,"snap":"2019-43-2019-47","text_gpt3_token_len":871,"char_repetition_ratio":0.13744205,"word_repetition_ratio":0.0093896715,"special_character_ratio":0.24652684,"punctuation_ratio":0.109375,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.95160276,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-10-21T20:42:36Z\",\"WARC-Record-ID\":\"<urn:uuid:1c5cf001-08ab-45bd-8414-3deec273aed5>\",\"Content-Length\":\"27677\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:f9823b10-cc10-4db2-9511-330c89ab9de3>\",\"WARC-Concurrent-To\":\"<urn:uuid:14b3057b-810f-4d00-b373-d44fb4432e5a>\",\"WARC-IP-Address\":\"194.1.147.58\",\"WARC-Target-URI\":\"https://financial-calculators.com/author/morris\",\"WARC-Payload-Digest\":\"sha1:WRQMFEXZJJVKA3H3YYGV3TGFNINKD3OU\",\"WARC-Block-Digest\":\"sha1:DL6HORDJGFRSUPOGQHANV66W5BQHSIMW\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-43/CC-MAIN-2019-43_segments_1570987787444.85_warc_CC-MAIN-20191021194506-20191021222006-00337.warc.gz\"}"} |
https://faculty.math.illinois.edu/Macaulay2/doc/Macaulay2-1.19/share/doc/Macaulay2/Graphs/html/_nonneighbors.html | [
"# nonneighbors -- returns the non-neighbors of a vertex in a graph\n\n## Synopsis\n\n• Usage:\nN = nonneighbors(G,v)\n• Inputs:\n• G, an instance of the type Graph,\n• v, ,\n• Outputs:\n• N, a set, the non-neighbors of vertex v in graph G\n\n## Description\n\nThe non-neighbors of a vertex v are all the vertexSet of G that are not adjacent to v. That is, if u is a non-neighbor to v, {u,v} is not an edge in G.\n\n i1 : G = graph({1,2,3,4},{{2,3},{3,4}}); i2 : nonneighbors(G,2) o2 = set {1, 4} o2 : Set"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.86037874,"math_prob":0.97917247,"size":290,"snap":"2023-14-2023-23","text_gpt3_token_len":105,"char_repetition_ratio":0.13636364,"word_repetition_ratio":0.0,"special_character_ratio":0.39310345,"punctuation_ratio":0.22619048,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.98799485,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-05-30T03:44:39Z\",\"WARC-Record-ID\":\"<urn:uuid:02bb2e4c-faf3-404c-8651-c9219f68d61e>\",\"Content-Length\":\"5449\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:0bf3e34d-07d9-4bd3-aa8d-ed686e1a83d0>\",\"WARC-Concurrent-To\":\"<urn:uuid:bd996e5f-9a88-481c-9cce-eb157ea86db2>\",\"WARC-IP-Address\":\"128.174.199.46\",\"WARC-Target-URI\":\"https://faculty.math.illinois.edu/Macaulay2/doc/Macaulay2-1.19/share/doc/Macaulay2/Graphs/html/_nonneighbors.html\",\"WARC-Payload-Digest\":\"sha1:S6H4OJTXYRW4PZRW7JE36HEZU2IWQOQX\",\"WARC-Block-Digest\":\"sha1:WSFSHFTAJ5CLYT3QSOBINCLAMN5L2ZLY\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-23/CC-MAIN-2023-23_segments_1685224645089.3_warc_CC-MAIN-20230530032334-20230530062334-00398.warc.gz\"}"} |
https://afd-wandsbek.de/site/article.php?e62e8c=clustering-with-scikit-with-gifs | [
"considers at each step all the possible merges. The two farthest subclusters are taken and for centroids to be the mean of the points within a given region. make_blobs() uses these parameters: n_samples is the total number of samples to generate. This should be all over Facebook!!!”. building block for a Consensus Index that can be used for clustering using sklearn.neighbors.kneighbors_graph to restrict Propagation on a synthetic 2D datasets with 3 classes. This global clusterer can be set by n_clusters. But it’s not all bad news. algorithm, and can be considered a generalization of DBSCAN that relaxes the Values closer to zero indicate a better This would happen when a non-core sample In the second This algorithm can be viewed as an instance or data reduction method, Single linkage is the most brittle linkage option with regard to this issue. exhaust system memory using HDBSCAN, OPTICS will maintain n (as opposed However, it’s also currently not included in scikit (though there is an extensively documented python package on github). Well, here’s the gif. cluster analysis as follows: The computation of Davies-Bouldin is simpler than that of Silhouette scores. Affinity propagation (AP) describes an algorithm that performs clustering by passing messages between points. homogeneous but not complete: v_measure_score is symmetric: it can be used to evaluate of core samples, which are samples that are in areas of high density. transform method of a trained model of KMeans. This technique is the application of the general expectation maximisation (EM) algorithm to the task of clustering. computations. as a dendrogram. To prevent the algorithm returning sub-optimal clustering, the kmeans method includes the n_init and method parameters. The contingency table calculated is typically utilized in the calculation For instance, in the swiss-roll example below, the connectivity The key difference Journal of the American Statistical Association. ‘Cutting’ the samples. If Different distance metrics can be supplied via the metric keyword. reachability-plot dendrograms, and the hierarchy of clusters detected by the 226–231. And in the world of big data, this matters. size of the clusters themselves. We’ve spent the past week counting words, and we’re just going to keep right on doing it. plot above has been color-coded so that cluster colors in planar space match labels_pred, the adjusted Rand index is a function that measures Given enough time, K-means will always converge, however this may be to a local style cluster extraction can be performed repeatedly in linear time for any Maybe humans (and data science blogs) will still be needed for a few more years! It is especially computationally efficient if the affinity matrix is sparse enable only merging of neighboring pixels on an image, as in the Why, you ask? shorter run time than OPTICS; however, for repeated runs at varying eps Two feature extraction methods can be used in … adjusted for chance and will tend to increase as the number of different labels As a rule of thumb if I’ll still provide some GIFs, but a mathematical description might be more informative in this case (i.e. observations of pairs of clusters. requires manual assignment by human annotators (as in the supervised learning In practice this difference in quality can be quite Algorithm description: It is based on minimization of the following objective function: In this equation, The The KMeans algorithm clusters data by trying to separate samples in n Due to this rather generic view, clusters Any sample that is not a also make the algorithm faster, especially when the number of the samples between DBSCAN and OPTICS is that the OPTICS algorithm builds a reachability Dremio. If GIFs aren’t your thing (what are you doing on the internet? with a small, all-equal, diagonal covariance matrix. and a set of non-core samples that are close to a core sample (but are not The code is modeled after the clustering algorithms in scikit-learn and has the same familiar interface. Instead, through the medium of GIFs, this tutorial will describe the most common techniques. extraction with OPTICS looks at the steep slopes within the graph to find Hierarchical clustering is a general family of clustering algorithms that clusters can be merged together), through a connectivity matrix that defines AP can suffer from non-convergence, though appropriate calibration of the damping parameter can minimise this risk. Given the knowledge of the ground truth class assignments labels_true and The best GIFs are on GIPHY. case of a signed distance matrix, is common to apply a heat kernel: See the examples for such an application. or within-cluster sum-of-squares criterion: Inertia can be recognized as a measure of how internally coherent clusters are. Prerequisite: Optimal value of K in K-Means Clustering K-means is one of the most popular clustering algorithms, mainly because of its good time performance. of pair of points that belong to the same clusters in the true labels and not max_eps to a lower value will result in shorter run times, and can be And it is not always possible for us to annotate data to certain categories or classes. clusters and ground truth classes, a completely random labeling will Search, discover and share your favorite Clustering GIFs. of cluster $$q$$, $$c_E$$ the center of $$E$$, and $$n_q$$ the The possibility to use custom metrics is retained; cluster is therefore a set of core samples, each close to each other when it is used jointly with a connectivity matrix, but is computationally Rosenberg and Hirschberg further define V-measure as the harmonic “A comparative analysis of ‘sqrt’ and ‘sum’ averages are the geometric and arithmetic means; we use these data is provided in a different order. A cluster with an index less than $$n$$ corresponds to one of the $$n$$ original observations. Some heuristics for choosing this parameter have been 2. Intuitively, these samples Sort: Relevant Newest # spot # cluster # kmeans # scikit # dashee87githubio spot # cluster # kmeans # scikit # dashee87githubio # season 3 # lisa simpson # episode 18 # watching # speaking (2017). Today, the majority of the mac… We’ll do an overview of this widely used module and get a bit more exposure to statistical learning algorithms. We’ll also explore an unsupervised learning technique - K-means cluster analysis (via R and then via Python using scikit-learn). red clusters are adjacent in the reachability plot, and can be hierarchically cosine distance is interesting because it is invariant to global Wikipedia entry for Davies-Bouldin index. If this split node has a parent subcluster and there is room the centroid of that cluster – also know as cluster diameter. is updated by taking the streaming average of the sample and all previous centers is the number of centers to generate. from one to another. set_option (\"display.max_columns\", 100) % matplotlib inline Even more text analysis with scikit-learn. Of them, none is in predicted cluster 0, one is in Set n_clusters to a required value using criterion is fulfilled. the impact of the dataset size on the value of clustering measures concepts of clusters, such as density based clusters like those obtained when given the same data in the same order. Visual inspection can often be useful for understanding the structure for any value of n_clusters and n_samples (which is not the It’s easy to imagine where you should overlay 4 balls on the first dataset. can be run over this with metric='precomputed'. is an example of such an evaluation, where a which define formally what we mean when we say dense. Average linkage minimizes the average of the distances between all how to find the optimal number of clusters). the silhouette analysis is used to choose an optimal value for n_clusters. For each sample in the mini-batch, the assigned centroid It is a Schubert, E., Sander, J., Ester, M., Kriegel, H. P., & Xu, X. through DBSCAN. measure class: center, middle ### W4995 Applied Machine Learning # Clustering and Mixture Models 03/27/19 Andreas C. Müller ??? 49-60. and DBSCAN one can also input similarity matrices of shape entropy of clusters $$H(K)$$ are defined in a symmetric manner. All the tools you’ll need are in Scikit-Learn, so I’ll leave the code to a minimum. while not robust to noisy data, can be computed very efficiently and can calculated using a similar form to that of the adjusted Rand index: For normalized mutual information and adjusted mutual information, the normalizing This page is based on a Jupyter/IPython Notebook: download the original .ipynb import pandas as pd pd. Demonstration of k-means assumptions: Demonstrating when Max no. Likewise for $$V$$: With $$P'(j) = |V_j| / N$$. observations of pairs of clusters. distances tend to become inflated We will use the models imported from Scikit-Learn. HC typically comes in two flavours (essentially, bottom up or top down): Another important concept in HC is the linkage criterion. E. B. Fowkles and C. L. Mallows, 1983. reports the intersection cardinality for every true/predicted cluster pair. More formally, we define a core sample as being a sample in the dataset such assignments that are largely independent, while values close to one The AgglomerativeClustering object performs a hierarchical clustering The algorithm is concisely illustrated by the GIF below. true cluster is “a”. The former just reruns the algorithm with n different initialisations and returns the best output (measured by the within cluster sum of squares). makes no distinction how the points are distributed within the ball), but, in some cases, a Gaussian kernel might be more appropriate. K-means is equivalent to the expectation-maximization algorithm discussed in the literature, for example based on a knee in the nearest neighbor uneven cluster sizes. There are two types of hierarchical clustering: Agglomerative and Divisive. The means are commonly called the cluster The Fowlkes-Mallows index (sklearn.metrics.fowlkes_mallows_score) can be No assumption is made on the cluster structure: can be used In particular random labeling won’t yield zero This initializes the centroids to be As we’ll find out though, that distinction can sometimes be a little unclear, as some algorithms employ parameters that act as proxies for the number of clusters. (generally) distant from each other, leading to provably better results than than a thousand and the number of clusters is less than 10. labelings), similar clusterings have a positive ARI, 1.0 is the perfect for the given data. to other points in their area, and will thus sometimes be marked as noise matrix. k-means performs intuitively and when it does not, A demo of K-Means clustering on the handwritten digits data: Clustering handwritten digits, “k-means++: The advantages of careful seeding” a(k,k) = \\sum_{i' \\neq k} \\max(0, r(i',k)). it into a global clusterer. separated by areas of low density. should be the exemplar for sample $$i$$. For this purpose, the two important approach. The centre of the ball is iteratively nudged towards regions of higher density by shifting the centre to the mean of the points within the ball (hence the name). These can be obtained from the functions L. Hubert and P. Arabie, Journal of Classification 1985, Wikipedia entry for the adjusted Rand index. As its name suggests, it constructs a hierarchy of clusters based on proximity (e.g Euclidean distance or Manhattan distance- see GIF below). In other words, it repeats of the ground truth classes while almost never available in practice or Visualization of cluster hierarchy, 2.3.10. BIRCH: An efficient data clustering method for large databases. k-means++ initialization scheme, which has been implemented in scikit-learn DBSCAN. The Birch algorithm has two parameters, the threshold and the branching factor. convergence. reducing the log-likelihood). number of points in cluster $$q$$. MiniBatch code, General-purpose, even cluster size, flat geometry, not too many clusters, Many clusters, uneven cluster size, non-flat geometry, Graph distance (e.g. Various Agglomerative Clustering on a 2D embedding of digits: exploration of the Peter J. Rousseeuw (1987). a non-flat manifold, and the standard euclidean distance is It can thus be used as a consensus and our clustering algorithm assignments of the same samples be used (e.g., with sparse matrices). However MI-based measures can also be useful in purely unsupervised setting as a cluster $$k$$, and finally $$n_{c,k}$$ the number of samples used when the ground truth class assignments of the samples is known. It’s clear that the default settings in the sklearn implementation of AP didn’t perform very well on the two datasets (in fact, neither execution converged). Andrew Y. Ng, Michael I. Jordan, Yair Weiss, 2001, “Preconditioned Spectral Clustering for Stochastic Clustering text documents using k-means. HDFS stands for Hadoop Distributed File System. clusters. Marina Meila, Jianbo Shi, 2001, “On Spectral Clustering: Analysis and an algorithm” This has the additional benefit of decreasing runtime (less steps to reach convergence). In most of the cases, data is generally labeled by us, human beings. Small affinity matrix between samples, followed by clustering, e.g., by KMeans, The messages sent between points belong to one of two categories. A simple choice to construct $$R_ij$$ so that it is nonnegative and representative of themselves. One method to help address this issue is the “A Dendrite Method for Cluster Analysis”. First, even though the core samples which is the accumulated evidence that sample $$i$$ sklearn.neighbors.kneighbors_graph. The score ranges from 0 to 1.\n\n## clustering with scikit with gifs\n\nCarrabba's Pasta Recipes, Cloud Computing Meaning, Expedition Lands Zendikar Rising Price List, East Kilbride Map, Patanjali Corona Kit Online, Aquatic Experts Bonded Filter Pad, Large Trumpet Vines For Sale, Fall Fashion Colors 2020, Tuba Büyüküstün News, Process Essays Topics, Is It Illegal To Curse At An Employee, When You Rise In The Morning Sun Lyrics,"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.6190845,"math_prob":0.931687,"size":442,"snap":"2022-05-2022-21","text_gpt3_token_len":121,"char_repetition_ratio":0.10045662,"word_repetition_ratio":0.027027028,"special_character_ratio":0.22171946,"punctuation_ratio":0.15384616,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.97539824,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-05-22T17:31:40Z\",\"WARC-Record-ID\":\"<urn:uuid:68bf0483-8df0-4328-94fb-10535f4c9319>\",\"Content-Length\":\"19051\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:d9a0713d-1a73-4249-ab43-f31a11d210a9>\",\"WARC-Concurrent-To\":\"<urn:uuid:144903f0-7b62-4fa8-8ed9-48d63b80ccfe>\",\"WARC-IP-Address\":\"88.99.139.237\",\"WARC-Target-URI\":\"https://afd-wandsbek.de/site/article.php?e62e8c=clustering-with-scikit-with-gifs\",\"WARC-Payload-Digest\":\"sha1:K53EWQOCRFNEPZZM6G34E6UCEJN6GJTI\",\"WARC-Block-Digest\":\"sha1:BJQN5LQSRCSHDQWWY2HDOZ22NN5RBPRD\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-21/CC-MAIN-2022-21_segments_1652662545875.39_warc_CC-MAIN-20220522160113-20220522190113-00770.warc.gz\"}"} |
https://imagination.readthedocs.io/en/latest/getting-started/04-create-with-parameters.html | [
"# Register a new entity with parameters¶\n\nNow, since we have one entity. Let’s spice things up with more complicate entity by creating a `Report` class at `app/report.py`:\n\n```class Report(object):\ndef __init__(self,\ncalculator,\nassignment_scores:list,\nfinal_exam_score:int):\nself.calculator = calculator\nself.assignment_scores = assignment_scores # max score = 10\nself.final_exam_score = final_exam_score # max score = 100\n\ntotal_scores = sum(self.assignment_scores)\ntotal_max_scores = (10 * len(self.assignment_scores))\nassignment_part = total_scores / total_max_scores\nfinal_exam_part = final_exam_score / 100\n\nassignment_part * 0.7,\nfinal_exam_part * 0.3\n)\n\n```\n\nAt this point, again, Imagination does not know about the report. To do so, let’s register an entity of an instance of app.report.Report in `containers.xml`:\n\n```<imagination>\n<!-- ... (omitted) ... -->\n<entity id=\"report.bob\" class=\"app.report.Report\">\n\n<!-- Pass [2, 0, 1, 8, 6, 9, 7, 5] (list of integers)\nas \"assignment_scores\" -->\n<param type=\"list\" name=\"assignment_scores\">\n<item type=\"int\">2</item>\n<item type=\"int\">0</item>\n<item type=\"int\">1</item>\n<item type=\"int\">8</item>\n<item type=\"int\">6</item>\n<item type=\"int\">9</item>\n<item type=\"int\">7</item>\n<item type=\"int\">5</item>\n</param>\n\n<!-- Pass 89 (integer)\nas \"final_exam_score\" -->\n<param type=\"int\" name=\"final_exam_score\">89</param>\n\n<!-- Pass the reference of the \"calc\" entity\nas \"calculator\" -->\n<param type=\"entity\" name=\"calculator\">calc</param>\n</entity>\n</imagination>\n```\n\nwhere report.bob is the entity ID.\n\nNote\n\nIn case you are confused, here is the equivalent code.\n\n```# From the previous page...\nfrom app.util import Calculator\n\ncalc = Calculator()\n\n# Now, to work with the report class.\nfrom app.report import Report\n\nreport = Report(calc, [2, 0, 1, 8, 6, 9, 7, 5], 89)\n```\n\nThe key differences at this point are:\n\n• neither the calc entity and the report.bob entity are not instantiated immediately until the report.bob entity is requested/activated,\n• the calc is always activated before the report.bob entity as calc is a dependency of report.bob.\n• the objects are still living only in the scope of the container.\n\n## How to work with the report entity¶\n\nTo refer the report entity, for example, in `main.py`, simply use `report_bob = assembler.core.get('report.bob')`\n\nNow, to actually use the entity, let’s add something to the end of `main.py`.\n\n```# Omitted the code for main.py already shown above\nreport_bob = assembler.core.get('report.bob')\n```\n\nSo, as you can see, the entity works pretty much like a normal object, except the key differences mentioned earlier.\n\n## What can you define as parameters or items?¶\n\nType Name Data Type Example PCDATA, child nodes\nstr Unicode (default) `bamboo`\nbool Boolean (bool) `true`, `false`\nfloat Float (float) `1.2`, `2.0`\nint Integer (int) `123`\nclass Class reference `argparser.ArgumentParser`\nentity An Imagination entity `report.bob` (Entity ID)\nlist Python’s List (list) (See an example below)\ndict Python’s Dictionary (dict) (See an example below)\n\nHere is an example. From:\n\n```<imagination>\n<entity class=\"foo.Bar\" id=\"panda\">\n<param type=\"bool\" name=\"enabled\">false</param>\n<param type=\"dict\" name=\"data\">\n<item type=\"list\" key=\"collection\">\n<item type=\"str\">shiroyuki</item>\n<item type=\"str\">is</item>\n<item type=\"str\">happy</item>\n</item>\n<item type=\"str\" key=\"code\">1234</item>\n</param>\n</entity>\n</imagination>\n```\n\nThe equivalence to the Python code used to instantiate this entity will be:\n\n```panda = foo.Bar(enabled = False, data = {\n'collection': ['shiroyuki', 'is', 'happy'],\n'code': 1234,\n})\n```\n\nNote\n\nHow to define parameters and items can be used with a factorized entity, which will be mentioned in the next step.\n\nTip"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.5727446,"math_prob":0.75595665,"size":4263,"snap":"2022-40-2023-06","text_gpt3_token_len":1160,"char_repetition_ratio":0.15637474,"word_repetition_ratio":0.01369863,"special_character_ratio":0.2894675,"punctuation_ratio":0.17128463,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9635437,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-01-27T23:39:25Z\",\"WARC-Record-ID\":\"<urn:uuid:79a8afbc-17f4-4a22-95ad-6bef99507696>\",\"Content-Length\":\"23779\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:6e620dca-5798-4278-89e6-05f8dcac244f>\",\"WARC-Concurrent-To\":\"<urn:uuid:c07596ef-ec0c-4e3d-8b91-2035caf6ae93>\",\"WARC-IP-Address\":\"104.17.32.82\",\"WARC-Target-URI\":\"https://imagination.readthedocs.io/en/latest/getting-started/04-create-with-parameters.html\",\"WARC-Payload-Digest\":\"sha1:MZMSDZ3RCC2UARGMMCWEUFT6CBMZHEUM\",\"WARC-Block-Digest\":\"sha1:MNVYGNUQAT3K5FJI5IO47AMWKYY4R3OO\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-06/CC-MAIN-2023-06_segments_1674764499468.22_warc_CC-MAIN-20230127231443-20230128021443-00706.warc.gz\"}"} |
https://forum.mango-os.com/topic/2829/chart-error-after-update | [
"# Chart error after update\n\n• Hello,\n\nI have just updated my Mango from v3.0.1 to v3.1.1. Previously I was able to take a virtual point using ma-point-values, and create a bar chart for the daily maximum for that point for the past week. The chart looked like this:",
null,
"Once I upgraded to 3.1.1, the chart is no longer working on the dashboard.\nI have copied the code to the play area, and it wont work there either. The code I used was:\n\n``````<ma-now update-interval=\"1 HOURS\" output=\"theTimeNow\"></ma-now>\n<ma-point-values point-xid=\"Site_Total_Real_Power\" point=\"point1\" values=\"max_val\" from=\"theTimeNow | moment:'startOf':'day'|moment:'subtract':7:'days'\" to=\"theTimeNow\" rollup=\"MAXIMUM\" rollup-interval=\"1 DAYS\">\n</ma-point-values>\n\n<ma-serial-chart style=\"height: 300px; width: 100%\" series-1-values=\"max_val\" series-1-point=\"point1\" default-type=\"column\">\n</ma-serial-chart>\n``````\n\nAdvice on why this output isn't working anymore would be really appreciated!\nHenry\n\n• @henryblu I think it's probably just the `moment` filters, change them to `maMoment`\n\n• Excellent! Thanks Jared, the following code worked perfectly:\n\n`````` <ma-now update-interval=\"1 HOURS\" output=\"theTimeNow\"></ma-now>\n<ma-point-values point-xid=\"Site_Total_Real_Power\" point=\"point1\" values=\"max_val\" from=\"theTimeNow | maMoment:'startOf':'day'|maMoment:'subtract':7:'days'\" to=\"theTimeNow\" rollup=\"MAXIMUM\" rollup-interval=\"1 DAYS\">\n</ma-point-values>\n\n<ma-serial-chart style=\"height: 300px; width: 100%\" series-1-values=\"max_val\" series-1-point=\"point1\" default-type=\"column\">\n</ma-serial-chart>\n\n``````"
] | [
null,
"https://i.imgur.com/YKB04fT.png",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.73191243,"math_prob":0.42744464,"size":1570,"snap":"2021-43-2021-49","text_gpt3_token_len":442,"char_repetition_ratio":0.11941252,"word_repetition_ratio":0.17964073,"special_character_ratio":0.27133757,"punctuation_ratio":0.12847222,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.97577983,"pos_list":[0,1,2],"im_url_duplicate_count":[null,3,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-10-28T18:29:10Z\",\"WARC-Record-ID\":\"<urn:uuid:33f36456-1dfd-4622-be87-bd07c365575a>\",\"Content-Length\":\"53651\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:27dac119-d3ea-438f-83c7-3b856ff8b710>\",\"WARC-Concurrent-To\":\"<urn:uuid:3ee9a1ce-3d88-43fe-9d88-b4e34932b12a>\",\"WARC-IP-Address\":\"192.241.207.234\",\"WARC-Target-URI\":\"https://forum.mango-os.com/topic/2829/chart-error-after-update\",\"WARC-Payload-Digest\":\"sha1:JWU4HGS7UNVF6VGP44AKNBIR2SEOTKE2\",\"WARC-Block-Digest\":\"sha1:BPLJAV5QL3XL7T7QMQXZX7SDQCOCI5IN\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-43/CC-MAIN-2021-43_segments_1634323588398.42_warc_CC-MAIN-20211028162638-20211028192638-00480.warc.gz\"}"} |
http://ixtrieve.fh-koeln.de/birds/litie/document/18886 | [
"# Document (#18886)\n\nAuthor\nDuchemin, P.-Y.\nTitle\n¬La recherche d'informations sur l'internet : repertoires et moteurs de recherche\nSource\nBulletin d'informations de l'Association des Bibliothecaires Francais. 1997, no.174, S.91-96\nYear\n1997\nAbstract\nThe Internet links computer networks worldwide through the TCP/IP; in addition to electronic mail; bulleton board and news group services, files can be downloaded using the standard protocol FTP. Services have evolved to identify and facilitate access to Internet resources, e.g. Telnet, Gopher, WAIS, etc. The WWW is the most developed, using hypertext links. Search engines such as AltaVista explore Web content and create catalogues of Web pages. Gives details of the most commonly used subject guides, research tools and search engines, including URL and applications\nFootnote\nÜbers. des Titels: Information research on the Internet: indexes and search engines\nTheme\nSuchmaschinen\n\n## Similar documents (author)\n\n1. Duchemin, P.-Y.: ¬La conversion retrospective des catalogues dur Départment des Cartes et Plans de la Bibliothèque Nationale (1994) 4.85\n```4.853387 = sum of:\n4.853387 = weight(author_txt:duchemin in 334) [ClassicSimilarity], result of:\n4.853387 = fieldWeight in 334, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n9.706774 = idf(docFreq=6, maxDocs=42306)\n0.5 = fieldNorm(doc=334)\n```\n2. Duchemin, P.-Y.: Retroconversion of French cartographic material card catalogues : an overview of the situation (1993) 4.85\n```4.853387 = sum of:\n4.853387 = weight(author_txt:duchemin in 479) [ClassicSimilarity], result of:\n4.853387 = fieldWeight in 479, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n9.706774 = idf(docFreq=6, maxDocs=42306)\n0.5 = fieldNorm(doc=479)\n```\n3. Duchemin, P.-Y.: BN-OPALINE (1997) 4.85\n```4.853387 = sum of:\n4.853387 = weight(author_txt:duchemin in 1911) [ClassicSimilarity], result of:\n4.853387 = fieldWeight in 1911, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n9.706774 = idf(docFreq=6, maxDocs=42306)\n0.5 = fieldNorm(doc=1911)\n```\n4. Duchemin, P.-Y.: BN OPALINE : the map database in the Department des Cartes et Plans de la Bibliothèque Nationale: history (1993) 4.85\n```4.853387 = sum of:\n4.853387 = weight(author_txt:duchemin in 1917) [ClassicSimilarity], result of:\n4.853387 = fieldWeight in 1917, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n9.706774 = idf(docFreq=6, maxDocs=42306)\n0.5 = fieldNorm(doc=1917)\n```\n5. Duchemin, P.-Y.: ¬La nemrisation des documents graphiques (1997) 4.85\n```4.853387 = sum of:\n4.853387 = weight(author_txt:duchemin in 1956) [ClassicSimilarity], result of:\n4.853387 = fieldWeight in 1956, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n9.706774 = idf(docFreq=6, maxDocs=42306)\n0.5 = fieldNorm(doc=1956)\n```\n\n## Similar documents (content)\n\n1. Valauskas, E.J.: TurboGopher: Internet access with ease on the Macintosh (1993) 0.22\n```0.2181304 = sum of:\n0.2181304 = product of:\n0.90887666 = sum of:\n0.09399241 = weight(abstract_txt:files in 4628) [ClassicSimilarity], result of:\n0.09399241 = score(doc=4628,freq=1.0), product of:\n0.13181166 = queryWeight, product of:\n1.0116476 = boost\n5.704649 = idf(docFreq=382, maxDocs=42306)\n0.022839976 = queryNorm\n0.7130811 = fieldWeight in 4628, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n5.704649 = idf(docFreq=382, maxDocs=42306)\n0.125 = fieldNorm(doc=4628)\n0.1483584 = weight(abstract_txt:protocol in 4628) [ClassicSimilarity], result of:\n0.1483584 = score(doc=4628,freq=1.0), product of:\n0.17868993 = queryWeight, product of:\n1.1778835 = boost\n6.642049 = idf(docFreq=149, maxDocs=42306)\n0.022839976 = queryNorm\n0.8302561 = fieldWeight in 4628, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n6.642049 = idf(docFreq=149, maxDocs=42306)\n0.125 = fieldNorm(doc=4628)\n0.0494704 = weight(abstract_txt:search in 4628) [ClassicSimilarity], result of:\n0.0494704 = score(doc=4628,freq=1.0), product of:\n0.108259395 = queryWeight, product of:\n1.2965823 = boost\n3.6556938 = idf(docFreq=2971, maxDocs=42306)\n0.022839976 = queryNorm\n0.45696172 = fieldWeight in 4628, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n3.6556938 = idf(docFreq=2971, maxDocs=42306)\n0.125 = fieldNorm(doc=4628)\n0.399642 = weight(abstract_txt:gopher in 4628) [ClassicSimilarity], result of:\n0.399642 = score(doc=4628,freq=4.0), product of:\n0.21793118 = queryWeight, product of:\n1.3008045 = boost\n7.335196 = idf(docFreq=74, maxDocs=42306)\n0.022839976 = queryNorm\n1.833799 = fieldWeight in 4628, product of:\n2.0 = tf(freq=4.0), with freq of:\n4.0 = termFreq=4.0\n7.335196 = idf(docFreq=74, maxDocs=42306)\n0.125 = fieldNorm(doc=4628)\n0.0726026 = weight(abstract_txt:internet in 4628) [ClassicSimilarity], result of:\n0.0726026 = score(doc=4628,freq=2.0), product of:\n0.11096689 = queryWeight, product of:\n1.3126956 = boost\n3.701125 = idf(docFreq=2839, maxDocs=42306)\n0.022839976 = queryNorm\n0.6542726 = fieldWeight in 4628, product of:\n1.4142135 = tf(freq=2.0), with freq of:\n2.0 = termFreq=2.0\n3.701125 = idf(docFreq=2839, maxDocs=42306)\n0.125 = fieldNorm(doc=4628)\n0.14481077 = weight(abstract_txt:links in 4628) [ClassicSimilarity], result of:\n0.14481077 = score(doc=4628,freq=1.0), product of:\n0.22153169 = queryWeight, product of:\n1.8547494 = boost\n5.2294374 = idf(docFreq=615, maxDocs=42306)\n0.022839976 = queryNorm\n0.65367967 = fieldWeight in 4628, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n5.2294374 = idf(docFreq=615, maxDocs=42306)\n0.125 = fieldNorm(doc=4628)\n0.24 = coord(6/25)\n```\n2. Lambert, S.: Internet basics : your online access to the global electronic super highway (1993) 0.22\n```0.21703468 = sum of:\n0.21703468 = product of:\n0.9043112 = sum of:\n0.13552836 = weight(abstract_txt:mail in 134) [ClassicSimilarity], result of:\n0.13552836 = score(doc=134,freq=1.0), product of:\n0.1449791 = queryWeight, product of:\n1.0609747 = boost\n5.9828033 = idf(docFreq=289, maxDocs=42306)\n0.022839976 = queryNorm\n0.934813 = fieldWeight in 134, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n5.9828033 = idf(docFreq=289, maxDocs=42306)\n0.15625 = fieldNorm(doc=134)\n0.061838 = weight(abstract_txt:search in 134) [ClassicSimilarity], result of:\n0.061838 = score(doc=134,freq=1.0), product of:\n0.108259395 = queryWeight, product of:\n1.2965823 = boost\n3.6556938 = idf(docFreq=2971, maxDocs=42306)\n0.022839976 = queryNorm\n0.57120216 = fieldWeight in 134, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n3.6556938 = idf(docFreq=2971, maxDocs=42306)\n0.15625 = fieldNorm(doc=134)\n0.24977623 = weight(abstract_txt:gopher in 134) [ClassicSimilarity], result of:\n0.24977623 = score(doc=134,freq=1.0), product of:\n0.21793118 = queryWeight, product of:\n1.3008045 = boost\n7.335196 = idf(docFreq=74, maxDocs=42306)\n0.022839976 = queryNorm\n1.1461244 = fieldWeight in 134, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n7.335196 = idf(docFreq=74, maxDocs=42306)\n0.15625 = fieldNorm(doc=134)\n0.06417224 = weight(abstract_txt:internet in 134) [ClassicSimilarity], result of:\n0.06417224 = score(doc=134,freq=1.0), product of:\n0.11096689 = queryWeight, product of:\n1.3126956 = boost\n3.701125 = idf(docFreq=2839, maxDocs=42306)\n0.022839976 = queryNorm\n0.5783008 = fieldWeight in 134, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n3.701125 = idf(docFreq=2839, maxDocs=42306)\n0.15625 = fieldNorm(doc=134)\n0.31381318 = weight(abstract_txt:telnet in 134) [ClassicSimilarity], result of:\n0.31381318 = score(doc=134,freq=1.0), product of:\n0.25374612 = queryWeight, product of:\n1.403628 = boost\n7.9150147 = idf(docFreq=41, maxDocs=42306)\n0.022839976 = queryNorm\n1.236721 = fieldWeight in 134, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n7.9150147 = idf(docFreq=41, maxDocs=42306)\n0.15625 = fieldNorm(doc=134)\n0.0791831 = weight(abstract_txt:most in 134) [ClassicSimilarity], result of:\n0.0791831 = score(doc=134,freq=1.0), product of:\n0.12765867 = queryWeight, product of:\n1.407967 = boost\n3.969741 = idf(docFreq=2170, maxDocs=42306)\n0.022839976 = queryNorm\n0.62027204 = fieldWeight in 134, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n3.969741 = idf(docFreq=2170, maxDocs=42306)\n0.15625 = fieldNorm(doc=134)\n0.24 = coord(6/25)\n```\n3. 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https://dofnews.com/what-are-the-6-trig-ratios/ | [
"# What are the 6 trig ratios?\n\n## What are the 6 trig ratios?\n\nThere are six trigonometric ratios, sine, cosine, tangent, cosecant, secant and cotangent. These six trigonometric ratios are abbreviated as sin, cos, tan, csc, sec, cot.\n\n## What are the 9 trig identities?\n\nAngle Sum and Difference Identities\n\n• Note which means you need to use plus or minus, and the.\n• sin(A B) = sin(A)cos(B) cos(A)sin(B)\n• cos(A B) = cos(A)cos(B) sin(A)sin(B)\n• tan(A B) = tan(A) tan(B)1 tan(A)tan(B)\n• cot(A B) = cot(A)cot(B) 1cot(B) cot(A)\n\n## Who is the daddy of trigonometry?\n\nHipparchus of Nicaea\n\n## What is SOH CAH TOA?\n\n“SOHCAHTOA” is a useful mnemonic for remembering the definitions of the trigonometric capabilities sine, cosine, and tangent i.e., sine equals reverse over hypotenuse, cosine equals adjoining over hypotenuse, and tangent equals reverse over adjoining, (1) (2) (3) Other mnemonics embody.\n\n## Is SOH CAH TOA just for proper triangles?\n\nQ: Is sohcahtoa just for proper triangles? A: Yes, it solely applies to proper triangles. A: They hypotenuse of a proper triangle is at all times reverse the 90 diploma angle, and is the longest aspect.\n\n180 levels\n\n## What is a forty five diploma triangle?\n\nUniv. of Wisconsin. A forty five 45 90 triangle is a particular kind of isosceles proper triangle the place the 2 legs are congruent to at least one one other and the non-right angles are each equal to 45 levels.\n\n## What is the 30-60-90 Triangle rule?\n\nTips for Remembering the 30-60-90 Rules Remembering the 30-60-90 triangle guidelines is a matter of remembering the ratio of 1: √3 : 2, and understanding that the shortest aspect size is at all times reverse the shortest angle (30°) and the longest aspect size is at all times reverse the biggest angle (90°).\n\n## What are the aspect lengths of a forty five 45 90 Triangle?\n\nA forty five°-45°-90° triangle is a particular proper triangle that has two 45-degree angles and one 90-degree angle. The aspect lengths of this triangle are within the ratio of; Side 1: Side 2: Hypotenuse = n: n: n√2 = 1:1: √2. The 45°-45°-90° proper triangle is half of a sq..\n\n## What do you name a forty five 45 90 Triangle?\n\nA forty five – 45 – 90 diploma triangle (or isosceles proper triangle) is a triangle with angles of 45°, 45°, and 90° and sides within the ratio of. Note that it’s the form of half a sq., lower alongside the sq.’s diagonal, and that it’s additionally an isosceles triangle (each legs have the identical size).\n\n## What is the rule for a forty five 4590 Triangle?\n\nThat tells us that for each 45-45-90 triangle, the size of the hypotenuse equals the size of the leg multiplied by sq. root of two. That is the 45-45-90 Triangle Theorem.\n\n## How do you discover the world of a forty five 45 90 proper triangle?\n\nCorrect reply: Explanation: To discover the world of a triangle, multiply the bottom by the peak, then divide by 2. Since the quick legs of an isosceles triangle are the identical size, we have to know just one to know the opposite. Since, a brief aspect serves as the bottom of the triangle, the opposite quick aspect tells us the peak.\n\n## What is the connection between the legs and the hypotenuse of a forty five 45 90 Triangle?\n\nIn different phrases, in each 45-45-90 triangle, the lengths of the 2 legs are at all times equal, and the ratio of the size of the hypotenuse to the size of a leg is at all times sq. root 2 to 1.\n\n## Is the hypotenuse of a 30 60 90 triangle is 3 √ instances so long as the shortest leg of the triangle?\n\n30°-60°-90° Triangles The measures of the edges are x, x√3, and 2x. In a 30°−60°−90° triangle, the size of the hypotenuse is twice the size of the shorter leg, and the size of the longer leg is √3 instances the size of the shorter leg.\n\n## How do you discover a 30 60 90 Triangle?\n\nA Quick Guide to the 30-60-90 Degree Triangle\n\n1. Type 1: You know the quick leg (the aspect throughout from the 30-degree angle). Double its size to seek out the hypotenuse.\n2. Type 2: You know the hypotenuse. Divide the hypotenuse by 2 to seek out the quick aspect.\n3. Type 3: You know the lengthy leg (the aspect throughout from the 60-degree angle).\n\n## What is the connection between the hypotenuse and the legs of a triangle?\n\nRecall {that a} proper triangle is a triangle the place one among its angles is 90 levels. For a proper triangle, the aspect that’s reverse of the precise angle known as the hypotenuse. This aspect will at all times be the longest aspect of the precise triangle. The different two (shorter) sides are known as legs.\n\nhypotenuse\n\n## Is Side A at all times longer than Side B in a proper triangle?\n\n2 Answers. Side A and B doesn’t matter when your attempting to use this to the pythagorean theorem however aspect C should at all times be the hypotenuse. The hypotenuse is at all times the triangle’s longest aspect. It is reverse the precise angle.\n\n## Which set of aspect will make a proper triangle?\n\nAll that you just want are the lengths of the bottom and the peak. In a proper triangle, the bottom and the peak are the 2 sides which kind the precise angle.\n\n## Does 4 5 6 make proper triangles?\n\nFor a set of three numbers to be pythagorean, the sq. of the biggest quantity needs to be equal to sum of the squares of different two. Hence 4 , 5 and 6 are usually not pythagorean triple.\n\n## Does 9 12 and 15 make a proper triangle?\n\nThe three sides 9 in, 12 in, and 15 in do symbolize a proper triangle. Since the sq. of the hypotenuse is the same as the sum of the squares of the opposite two sides, it is a proper triangle.\n\n## Does 5 12 and 13 kind a proper triangle?\n\nYes, a proper triangle can have aspect lengths 5, 12, and 13. To decide if sides of size 5, 12, and 13 models could make up the edges of a proper…\n\n## Does 7/11/13 kind a proper triangle?\n\nBecause the 2 sides are equal, it is a proper triangle. NOTE: All of the lengths in Example 4 symbolize the lengths of the edges of a triangle. For instance, 4, 7 and 13 can’t be the edges of a triangle as a result of start{align*}4+7end{align*} isn’t better than 13.\n\n## Does 4 8 12 make proper triangles?\n\nAnswer: No, aspect lengths of 4, 8, and 12 don’t kind a proper triangle.\n\n## Does 15 36 39 kind a proper triangle?\n\nExample 1: Solve for x. Therefore, the size of the bottom x of the triangle is roughly 12.1. The Converse of the Pythagorean Theorem states that, if is true, then the given triangle is a proper triangle. Hence, the set {15, 36, 39} is a Pythagorean Triple."
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https://byjus.com/questions/copy-the-following-drawing-on-squared-paper-complete-each-one-of-them-such-that-the-resulting-figure-has-two-dotted-lines-as-two-lines-of-symmetry-how-did-you-go-about-completing-the-picture/ | [
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"# Copy the following drawing on squared paper. Complete each one of them such that the resulting figure has two dotted lines as two lines of symmetry. How did you go about completing the picture?",
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"Solutions:\n\nWe can complete the given figures by drawing similar parts as shown in these figures.\n\nLet us first draw the vertical line of symmetry and then the horizontal line of symmetry. Or first about the horizontal line of symmetry and then about the vertical line of symmetry.\n\nThe figures shown below are the completed figures the given above",
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"https://cdn1.byjus.com/wp-content/uploads/2019/11/ncert-solutions-for-class-6-maths-chapter-13-exerc-48.png",
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"https://cdn1.byjus.com/wp-content/uploads/2019/11/ncert-solutions-for-class-6-maths-chapter-13-exerc-49.png",
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https://boundaryvalueproblems.springeropen.com/articles/10.1186/s13661-015-0368-7 | [
"# Dynamics of competing systems in general heterogeneous environments\n\n## Abstract\n\nIn this paper, we address the question of the dynamics of the systems for two competing species in general heterogeneous environment with lethal boundary conditions. The existence and uniqueness of the positive steady-state solution are established under suitable conditions. Finally, we obtain global asymptotic stability of the positive steady-state solution for weak competition situation.\n\n## 1 Introduction\n\nThe model we consider has the general form\n\n$$\\left \\{ \\textstyle\\begin{array}{@{}l@{\\quad}l} \\frac{\\partial u}{\\partial t}=\\mu_{1}\\Delta u+u[a(x)-b(x)u-c(x)v] &\\mbox{in } \\Omega\\times[0,\\infty),\\\\ \\frac{\\partial v}{\\partial t}=\\mu_{2}\\Delta v+v[d(x)-e(x)u-f(x)v] &\\mbox{in } \\Omega\\times[0,\\infty),\\\\ u=v=0 &\\mbox{on } \\partial\\Omega\\times[0,\\infty),\\\\ u(x,0)=u^{0}(x),\\qquad v(x,0)=v^{0}(x) &\\mbox{in } \\partial\\Omega, \\end{array}\\displaystyle \\right .$$\n(1.1)\n\nwhere $$a(x), b(x), d(x), f(x)>0$$, $$c(x), e(x)\\geq0$$, all belong to the Hölder space $$C^{\\alpha}(\\overline{\\Omega})$$ for some constant $$0<\\alpha<1$$, and $$\\Omega\\subseteq\\mathbb{R}^{N}$$ is a bounded domain with $$C^{2+\\alpha}$$ a smooth boundary. The variables u, v represent population densities of the competing species. The boundary condition describes the situation that the boundary of Ω is lethal to the species.\n\nWhen the coefficients $$a(x)$$, $$b(x)$$, $$c(x)$$, $$d(x)$$, $$e(x)$$, $$f(x)$$ are constants (homogeneous environment), the system (1.1) has been studied extensively in past years; see, for example, and the references therein. But in the real world, the environments are usually heterogenous, and so it is more reasonable to assume that the coefficients in the system (1.1) are more general functions . Recently, He and Ni studied the dynamics of a competition model in some heterogeneous environments with Neumann boundary conditions [8, 9]. Álvarez-Caudevilla et al. considered a cooperative reaction-diffusion system in a spatiotemporally degenerate environment .\n\nTo study the dynamics of the system (1.1), we will consider its steady-state equation,\n\n$$\\left \\{ \\textstyle\\begin{array}{@{}l@{\\quad}l} \\mu_{1}\\Delta u+u[a(x)-b(x)u-c(x)v]=0 & \\mbox{in } \\Omega\\times [0,\\infty),\\\\ \\mu_{2}\\Delta v+v[d(x)-e(x)u-f(x)v]=0 & \\mbox{in } \\Omega\\times [0,\\infty),\\\\ u=v=0 & \\mbox{on } \\partial\\Omega\\times[0,\\infty). \\end{array}\\displaystyle \\right .$$\n(1.2)\n\nLet $$\\lambda_{1}>0$$ denote the principal eigenvalue for the problem\n\n$$\\left \\{ \\textstyle\\begin{array}{@{}l@{\\quad}l} \\Delta\\phi+\\lambda\\phi=0 &\\mbox{in } \\Omega,\\\\ \\phi=0 &\\mbox{on } \\partial\\Omega. \\end{array}\\displaystyle \\right .$$\n(1.3)\n\nFor any $$A(x)\\in C^{\\alpha}(\\overline{\\Omega})$$, it is well known that\n\n$$\\left \\{ \\textstyle\\begin{array}{@{}l@{\\quad}l} \\mu\\Delta\\theta+\\theta(A(x)-\\theta)=0 &\\mbox{in } \\Omega,\\\\ \\theta=0 &\\mbox{on } \\partial\\Omega, \\end{array}\\displaystyle \\right .$$\n(1.4)\n\nhas a unique positive solution $$\\theta\\in C^{2+\\alpha}(\\overline{\\Omega})$$ if $$A(x)>\\mu\\lambda_{1}$$ for all $$x\\in\\overline{\\Omega}$$ . We denote this unique positive solution by $$\\theta_{\\mu, A(x)}$$.\n\nIn the rest of the paper, we always assume that\n\n$$a(x)>\\mu_{1}\\lambda_{1}, \\qquad d(x)> \\mu_{2}\\lambda_{1} \\quad \\mbox{for all } x\\in\\overline{ \\Omega},$$\n(1.5)\n\nand denote\n\n$$\\bar{u}(x)=\\frac{\\theta_{\\mu_{1}, a(x)}}{\\min_{x\\in\\overline{\\Omega }}b(x)}, \\qquad\\bar{v}(x)=\\frac{\\theta_{\\mu_{2}, d(x)}}{\\min_{x\\in\\overline {\\Omega}}f(x)}, \\quad x\\in\\overline{\\Omega}.$$\n(1.6)\n\nNow we state the existence result for steady-state solutions.\n\n### Theorem 1.1\n\n(Existence)\n\nIf\n\n$$a(x)>\\mu_{1}\\lambda_{1}+c(x)\\bar{v}(x), \\qquad d(x)>\\mu_{2}\\lambda_{1}+e(x)\\bar{u}(x),$$\n(1.7)\n\nfor all $$x\\in\\overline{\\Omega}$$, then the system (1.2) has a positive steady-state solution $$(\\tilde{u}(x), \\tilde{v}(x))$$ with $$\\tilde{u}(x), \\tilde{v}(x)\\in C^{2+\\alpha}(\\overline{\\Omega})$$.\n\nNow we suppose further that the two competitors in (1.1) are under weak competition in the sense that $$c(x), e(x)>0$$ are small such that\n\n$$\\frac{c(x)}{\\min_{x\\in\\overline{\\Omega}}f(x)}< \\frac{a(x)}{d(x)}, \\qquad \\frac{e(x)}{\\min_{x\\in\\overline{\\Omega}}b(x)}< \\frac{d(x)}{a(x)}\\quad \\mbox{for all } x\\in\\overline{\\Omega}.$$\n(1.8)\n\nWe denote\n\n\\begin{aligned} &\\bar{\\zeta}=\\theta_{\\mu_{1}, a(x)}, \\qquad \\bar{\\eta}= \\theta_{\\mu_{2}, d(x)}, \\\\ &\\underline{\\zeta}=\\theta_{\\mu_{1}, (a(x)-c(x)\\frac{d(x)}{\\min_{x\\in \\overline{\\Omega}}f(x)})}, \\qquad \\underline{\\eta}= \\theta_{\\mu_{2}, (d(x)-e(x)\\frac{a(x)}{\\min_{x\\in \\overline{\\Omega}}b(x)})}, \\end{aligned}\n(1.9)\n\nwhich are all positive functions in Ω.\n\nThe following theorem gives a sufficient conditions for uniqueness of coexistence solution in suitable weak competition situations.\n\n### Theorem 1.2\n\n(Uniqueness)\n\nAssume that all the hypotheses of Theorems 1.1 and (1.8) are satisfied. If\n\n$$\\frac{c^{2}(x)\\bar{\\zeta}}{b^{2}(x)\\underline{\\eta}} +2\\frac{c(x)e(x)}{b(x)f(x)}+\\frac{e^{2}(x)\\bar{\\eta}}{f^{2}(x)\\underline {\\zeta}}< 4, \\quad x \\in\\overline{\\Omega},$$\n(1.10)\n\nthen the steady-state solution $$(\\tilde{u}(x), \\tilde{v}(x))$$ of (1.2) is unique.\n\n### Remark 1.1\n\nFor fixed functions $$a(x)>0$$, $$d(x)>0$$, hypothesis (1.10) will be satisfied for $$c(x), e(x)\\geq0$$ sufficiently small. This is true because $$\\underline{\\zeta}$$ (resp. $$\\underline{\\eta}$$) increases as $$c(x)$$ (resp. $$e(x)$$) decreases for $$x\\in\\Omega$$. Thus $$\\frac{e^{2}(x)\\bar{\\eta }}{f^{2}(x)\\underline{\\zeta}}$$ (resp. $$\\frac{c^{2}(x)\\bar{\\zeta }}{b^{2}(x)\\underline{\\eta}}$$) decreases as $$c(x)$$ (resp. $$e(x)$$) decreases.\n\nFinally, we state our dynamics results for the system (1.1).\n\n### Theorem 1.3\n\n(Global asymptotic stability)\n\nAssume that the hypotheses of Theorem 1.2 are satisfied. Let $$(u(x,t), v(x,t))$$ be a solution of the initial boundary value problem (1.1) with both $$u^{0}, v^{0}\\geq0,\\not\\equiv0$$ in $$C^{\\alpha}(\\overline{\\Omega })$$, $$0<\\alpha<1$$, and vanishing on Ω, then\n\n$$\\bigl(u(x,t), v(x,t)\\bigr)\\rightarrow\\bigl(\\tilde{u}(x), \\tilde{u}(x)\\bigr) \\quad \\textit{as } t\\rightarrow\\infty$$\n\nuniformly in $$\\overline{\\Omega}$$.\n\nThis paper is organized as follows: Theorem 1.1 and Theorem 1.2 are proved in Section 2. Theorem 1.3 is established in Section 3 by proving a more general theorem.\n\n## 2 Proof of Theorem 1.1 and Theorem 1.2\n\n### Proof of Theorem 1.1\n\nLet $$\\phi(x)$$ be a positive eigenfunction of the principal eigenvalue $$\\lambda_{1}$$ for the eigenvalue problem (1.3). Choose $$r_{1}>0$$ sufficiently small,\n\n\\begin{aligned} &\\mu_{1}\\Delta\\bigl(r_{1}\\phi(x)\\bigr)+r_{1} \\phi(x)\\bigl[(a(x)-b(x)r_{1}\\phi (x)-c(x)v\\bigr] \\\\ &\\quad\\geq r_{1}\\phi(x)\\bigl[(a(x)-\\mu_{1} \\lambda_{1}-b(x)r_{1}\\phi(x)-c(x)\\bar {v}\\bigr]\\geq0 \\end{aligned}\n\nand\n\n\\begin{aligned} &\\mu_{1}\\Delta\\bar{u}+\\bar{u}\\bigl[a(x)-b(x)\\bar{u}-c(x)v\\bigr] \\\\ &\\quad=\\bar{u} \\biggl[\\biggl(1-\\frac{b(x)}{\\min_{x\\in\\overline{\\Omega }}b(x)}\\biggr)\\theta_{\\mu_{1}, a(x)}-c(x)v \\biggr]\\leq0 \\end{aligned}\n\nfor all $$0\\leq v\\leq\\bar{v}$$. So, $$(\\bar{u}, r_{1}\\phi(x))$$ is a set of upper and lower solutions for u in (1.2).\n\nSimilarly, choose $$r_{2}>0$$ sufficiently small, $$(\\bar{v}, r_{2}\\phi (x))$$ is a set of upper and lower solutions for v in (1.1). By the coupled upper and lower theorem , the system (1.2) has a steady-state solution $$(\\tilde{u}(x), \\tilde{v}(x))$$ with $$\\tilde{u}(x), \\tilde{v}(x)>0$$ for $$x\\in\\Omega$$. □\n\n### Proof of Theorem 1.2\n\nAssume that $$(\\tilde {u}_{1}(x), \\tilde{v}_{1}(x)), (\\tilde{u}_{2}(x), \\tilde{v}_{2}(x))$$ are two strictly positive steady-state solutions of the system (1.1) in Ω.\n\nLet\n\n\\begin{aligned}& p(x)=\\tilde{u}_{1}(x)-\\tilde{u}_{2}(x),\\qquad q(x)=\\tilde {v}_{1}(x)-\\tilde{v}_{2}(x), \\\\& I_{1}=b(x)\\tilde{u}_{2}(x)p(x)+c(x)\\tilde{u}_{2}(x)q(x), \\\\& I_{2}=e(x)\\tilde{v}_{1}(x)p(x)+f(x)\\tilde{v}_{1}(x)q(x), \\end{aligned}\n\nthen\n\n$$\\left \\{ \\textstyle\\begin{array}{@{}l@{\\quad}l} \\mu_{1}\\Delta p(x)+[a(x)-b(x)\\tilde{u}_{1}(x)-c(x)\\tilde {v}_{1}(x)]p(x)-I_{1}=0 &\\mbox{in } \\Omega,\\\\ \\mu_{2}\\Delta q(x)+[d(x)-e(x)\\tilde{u}_{2}(x)-f(x)\\tilde {v}_{2}(x)]q(x)-I_{2}=0 &\\mbox{in } \\Omega,\\\\ p(x)=q(x)=0 &\\mbox{on } \\partial\\Omega. \\end{array}\\displaystyle \\right .$$\n(2.1)\n\nSince $$\\tilde{u}_{1}(x)$$ is a strictly positive solution of\n\n$$\\left \\{ \\textstyle\\begin{array}{@{}l@{\\quad}l} \\mu_{1}\\Delta\\psi+[a(x)-b(x)\\tilde{u}_{1}(x)-c(x)\\tilde {v}_{1}(x)]\\psi+\\alpha\\psi=0 &\\mbox{in } \\Omega,\\\\ \\psi=0 &\\mbox{on } \\partial\\Omega, \\end{array}\\displaystyle \\right .$$\n\nwith $$\\alpha=0$$, the number $$\\alpha=0$$ must be the smallest eigenvalue of the above problem. Moreover, by the variational properties, we have\n\n$$\\int_{\\Omega}z\\bigl(-\\mu_{1}\\Delta z- \\bigl[a(x)-b(x)\\tilde{u}_{1}(x)-c(x)\\tilde {u}_{2}(x)\\bigr]z \\bigr)\\,dx\\geq0,$$\n(2.2)\n\nfor any $$z\\in C^{2}(\\overline{\\Omega})$$ which vanishes on Ω. Similarly, since $$\\tilde{v}_{2}(x)$$ is strictly positive solution of\n\n$$\\left \\{ \\textstyle\\begin{array}{@{}l@{\\quad}l} \\mu_{2}\\Delta\\psi+[d(x)-e(x)\\tilde{u}_{2}(x)-f(x)\\tilde {v}_{2}(x)]\\psi+\\alpha\\psi=0 &\\mbox{in } \\Omega,\\\\ \\psi=0 &\\mbox{on } \\partial\\Omega, \\end{array}\\displaystyle \\right .$$\n\nwith $$\\alpha=0$$, the number $$\\alpha=0$$ must be the smallest eigenvalue of the above problem. Moreover,\n\n$$\\int_{\\Omega}z\\bigl(-\\mu_{2}\\Delta z- \\bigl[d(x)-e(x)\\tilde{u}_{2}(x)-f(x)\\tilde {v}_{2}(x)\\bigr]z \\bigr)\\,dx\\geq0,$$\n(2.3)\n\nfor any $$z\\in C^{2}(\\overline{\\Omega})$$ which vanishes on Ω. Multiplying the first equation of (2.1) by $$-p(x)$$, the second by $$-q(x)$$, integrating over Ω, and adding, we deduce from (2.2) and (2.3) that\n\n$$\\int_{\\Omega}\\bigl[b(x)\\tilde{u}_{2}(x)p^{2}(x)+ \\bigl(c(x)\\tilde {u}_{2}(x)+e(x)\\tilde{v}_{1}(x) \\bigr)p(x)q(x)+f(x) \\tilde{v}_{2}(x)q^{2}(x)\\bigr]\\,dx\\leq0.$$\n(2.4)\n\nBy a comparison of scalar equations using upper and lower solutions we readily obtain, for $$x\\in\\Omega$$,\n\n\\begin{aligned} &\\frac{\\underline{\\zeta}}{b(x)}\\leq \\tilde{u}_{1}, \\tilde{u}_{2}\\leq \\frac{\\bar{\\zeta}}{b(x)}, \\\\ &\\frac{\\underline{\\eta}}{f(x)}\\leq\\tilde{v}_{1}, \\tilde{v}_{2}\\leq \\frac{\\bar{\\eta}}{f(x)}. \\end{aligned}\n(2.5)\n\nFrom (2.5), we have\n\n\\begin{aligned} &\\frac{f(x)c^{2}(x)\\bar{\\zeta}}{b(x)\\underline{\\eta}}+2c(x)e(x)+\\frac {b(x)e^{2}(x)\\bar{\\eta}}{f(x)\\underline{\\zeta}} >c^{2}(x)\\frac{\\tilde{u}_{2}(x)}{\\tilde{v}_{1}(x)}+2c(x)e(x) +e^{2}(x) \\frac{\\tilde{v}_{1}(x)}{\\tilde{u}_{2}(x)}, \\end{aligned}\n(2.6)\n\nin Ω. It follows from (1.10) that\n\n$$c^{2}(x)\\frac{\\tilde{u}_{2}(x)}{\\tilde{v}_{1}(x)}+2c(x)e(x) +e^{2}(x) \\frac{\\tilde{v}_{1}(x)}{\\tilde{u}_{2}(x)}< 4b(x)f(x) \\quad\\mbox{in } \\Omega.$$\n(2.7)\n\nThen it is easy to see that the quadratic expression in the integrand of (2.4) is positive definite for each $$x\\in\\Omega$$. Consequently, we must have $$p(x)$$ and $$q(x)$$ identically equal to zero in Ω. That is, $$(\\tilde{u}_{1}(x),\\tilde{v}_{2}(x))\\equiv(\\tilde {u}_{2}(x),\\tilde{v}_{2}(x))$$ in Ω. □\n\n## 3 Proof of Theorem 1.3\n\nNow we are in a position to prove Theorem 1.3. Note that, by Theorem 1.2 and the assumptions of Theorem 1.3, problem (1.2) has a unique positive solution $$(\\tilde{u}(x), \\tilde{u}(x))$$. Then we will establish Theorem 1.3 by proving the following theorem without the assumption (1.10).\n\n### Theorem 3.1\n\nAssume the hypotheses of Theorem 1.1 and that problem (1.2) has a unique positive solution $$(\\tilde{u}(x), \\tilde{u}(x))$$ in Ω, then $$(\\tilde{u}(x), \\tilde{u}(x))$$ is globally asymptotically stable in the following sense. Let $$(u(x,t), v(x,t))$$ be a solution of the initial boundary value problem (1.1) with both $$u^{0}, v^{0}\\geq0,\\not\\equiv0$$ in $$C^{\\alpha}(\\overline{\\Omega})$$, $$0<\\alpha<1$$, and vanishing on Ω, then\n\n$$\\bigl(u(x,t), v(x,t)\\bigr)\\rightarrow\\bigl(\\tilde{u}(x), \\tilde{u}(x)\\bigr) \\quad\\textit{as } t\\rightarrow\\infty,$$\n\nuniformly in $$\\overline{\\Omega}$$.\n\n### Proof\n\nFor convenience, we introduce the following notation: If $$w\\in C^{1}(\\overline{\\Omega})$$, $$w(x)>0$$ for all $$x\\in\\Omega$$, and $$\\partial w/\\partial\\nu<0$$ everywhere on Ω, we write $$w\\gg0$$. If $$w, z\\in C^{1}(\\overline{\\Omega})$$, we write $$w\\ll z$$ if $$z-w \\gg0$$. We first prove the theorem under the additional conditions $$u^{0}, v^{0}\\in C^{1}(\\overline{\\Omega})$$,\n\n$$u^{0}\\gg0, \\qquad v^{0}\\gg0,$$\n(3.1)\n\nand for all $$x\\in\\overline{\\Omega}$$,\n\n$$u^{0}\\leq\\bar{u}, \\qquad v^{0}\\leq\\bar{v},$$\n(3.2)\n\nwhere $$\\bar{u}$$ and $$\\bar{v}$$ are defined in (1.6).\n\nLet $$\\phi_{1}$$ be the positive eigenfunction of the principal eigenvalue in (1.3). Choose $$\\epsilon>0$$ small such that\n\n$$\\epsilon\\phi_{1}(x)\\leq u^{0}(x), \\qquad \\epsilon\\phi_{1}(x)\\leq v^{0}(x),$$\n(3.3)\n\nand\n\n\\begin{aligned} &a(x)>\\mu_{1} \\lambda_{1}+c(x)\\bar{v}+b(x)\\epsilon\\phi_{1}(x), \\\\ &d(x)>\\mu_{2}\\lambda_{1}+e(x)\\bar{u}+f(x)\\epsilon \\phi_{1}(x), \\end{aligned}\n(3.4)\n\nfor all $$x\\in\\overline{\\Omega}$$. If we let $$\\underline{u}=\\underline {v}=\\epsilon\\phi_{1}$$, then\n\n$$\\mu_{1}\\Delta\\bar{u}+\\bar{u}\\bigl[a(x)-b\\bar{u}-c(x)\\underline{v} \\bigr]=\\bar {u}\\biggl[\\biggl(1-\\frac{b(x)}{\\min_{x\\in\\overline{\\Omega}}b(x)}\\biggr)\\theta_{\\mu_{1}, a(x)}-c(x) \\underline{v}\\biggr]< 0,$$\n\nfor all $$x\\in\\Omega$$; and from (3.4), we have\n\n$$\\mu_{2}\\Delta\\underline{v}+\\underline{v}\\bigl[d(x)-e\\bar{u}-f(x) \\underline {v}\\bigr]=\\underline{v}\\bigl[d(x)-\\mu_{2} \\lambda_{1}-e(x)\\bar{u}-f(x)\\underline{v}\\bigr]>0,$$\n\non Ω. Similarly, we have\n\n\\begin{aligned}& \\mu_{1}\\Delta\\underline{u}+\\underline{u}\\bigl[a(x)-b(x) \\underline{u}-c(x)\\bar{v}\\bigr]>0, \\\\& \\mu_{2}\\Delta\\bar{v}+\\bar{v}\\bigl[d(x)-e(x)\\underline{u}-f(x)\\bar{v} \\bigr]< 0. \\end{aligned}\n\nBy Theorem 1.3 in (also see Pao , Section 10.5), the conclusion of the theorem follows from the uniqueness assumption, the inequalities $$\\underline {u}(x)\\leq u^{0}\\leq\\bar{u}(x)$$, $$\\underline{v}(x)\\leq v^{0}\\leq\\bar{v}(x)$$, $$x\\in\\overline{\\Omega}$$, and a comparison with solutions of the differential system (1.1) with initial conditions replaced at the steady-state upper lower solutions $$(\\bar{u}(x), \\underline{v}(x))$$.\n\nWe next remove condition (3.2) on the initial functions $$u^{0}(x)$$, $$v^{0}(x)$$. First, observe that there exists large $$K>1$$, such that\n\n$$u^{0}(x)\\leq K\\bar{u}, \\qquad V^{0}(x)\\leq K\\bar{v},$$\n\non Ω. Define $$(\\overline{U}(x,t), \\underline{V}(x,t))$$ to be the solution of problem (1.1) with initial conditions replaced with\n\n$$\\bigl(\\overline{U}(x,0), \\underline{V}(x,0)\\bigr)=(K\\bar{u}, 0).$$\n\nIt is clear that $$\\underline{V}\\equiv0$$, $$\\overline{U}$$ is non-negative in $$\\Omega\\times[0, \\infty)$$ and\n\n$$\\lim_{t\\rightarrow\\infty}\\overline{U}(x,t)= \\overline{U}^{\\star}(x) \\quad \\mbox{for } x\\in\\Omega,$$\n(3.5)\n\nwhere $$\\overline{U}^{\\star}(x)$$ is the unique positive solution of the problem\n\n$$\\mu_{1}\\Delta z+z\\bigl[a(x)-b(x)z\\bigr]=0 \\quad\\mbox{in } \\Omega, \\qquad z=0 \\quad\\mbox{on } \\partial\\Omega.$$\n(3.6)\n\nMoreover, the convergence above is monotone, because $$\\overline {U}(x,0)$$, $$\\underline{V}(x,0)$$ satisfies\n\n\\begin{aligned}& \\mu_{1}\\Delta\\overline{U}(x,0)+\\overline{U}(x,0)\\bigl[a(x)-b(x) \\overline {U}(x,0)-c(x)\\underline{V}(x,0)\\bigr]\\\\& \\quad=\\bigl(\\overline{U}(x,0) \\bigr)^{2}\\biggl[\\frac{\\min_{x\\in\\overline{\\Omega}}b(x)}{K}-b\\biggr]< 0, \\\\& \\mu_{2}\\Delta\\underline{V}(x,0)+\\underline{V}(x,0)\\bigl[d(x)-e(x) \\overline {U}(x,0)-f(x)\\underline{V}(x,0)\\bigr]=0. \\end{aligned}\n\nThe convergence in (3.5) is also in $$C^{1}(\\overline {\\Omega})$$ norm by using the $$W^{2,p}$$ estimates, compact embedding, and (1.1). Similarly, define $$(\\underline{U}(x,t), \\overline{V}(x,t))$$ to be the solution of problem (1.1) with initial conditions replaced with\n\n$$\\bigl(\\underline{U}(x,0), \\overline{V}(x,0)\\bigr)=(0, K\\bar{v}).$$\n\nWe have $$\\underline{U}\\equiv0$$, $$\\overline{V}$$ is non-negative in $$\\Omega\\times[0, \\infty)$$, and we have monotone $$C^{1}(\\overline{\\Omega })$$ convergence,\n\n$$\\lim_{t\\rightarrow\\infty}\\overline{V}(x,t)= \\overline{V}^{\\star}(x),$$\n(3.7)\n\nwhere $$\\overline{V}^{\\star}(x)$$ is the unique positive solution of the problem\n\n$$\\mu_{2}\\Delta z+z\\bigl[d(x)-f(x)z\\bigr] \\quad\\mbox{in } \\Omega, \\qquad z|_{\\partial\\Omega}=0.$$\n(3.8)\n\nOn the other hand, one readily verifies that the functions $$\\underline {U}(x,t)$$, $$\\overline{U}(x,t)$$, $$\\underline{V}(x,t)$$, $$\\overline {V}(x,t)$$ satisfy\n\n\\begin{aligned} &\\mu_{1}\\Delta\\overline{U}+ \\overline{U}\\bigl[a(x)-b(x)\\overline {U}-c(x)\\underline{V}\\bigr]-\\partial \\overline{U}/\\partial t< 0, \\\\ &\\mu_{2}\\Delta\\underline{V}+\\underline{V}\\bigl[d(x)-e(x)\\overline {U}-f(x)\\underline{V}\\bigr]-\\partial\\underline{V}/\\partial t\\geq0, \\\\ &\\mu_{2}\\Delta\\overline{V}+\\overline{V}\\bigl[d(x)-e(x)\\underline {U}-f(x)\\overline{V}\\bigr]-\\partial\\overline{V}/\\partial t< 0, \\\\ &\\mu_{1}\\Delta\\underline{U}+\\underline{U}\\bigl[a(x)-b(x)\\underline {U}-c(x)\\overline{V}\\bigr]-\\partial\\underline{U}/\\partial t\\geq0, \\end{aligned}\n(3.9)\n\nfor $$(x,t)\\in\\Omega\\times(0, \\infty)$$, and\n\n\\begin{aligned} &0=\\underline{U}(x,0)\\leq u^{0}(x)\\leq \\overline{U}(x,0)=K\\bar{u}, \\\\ &0=\\underline{V}(x,0)\\leq v^{0}(x)\\leq\\overline{V}(x,0)=K\\bar{v}, \\end{aligned}\n(3.10)\n\nfor $$x\\in\\overline{\\Omega}$$. From the comparison theorems, we assert that\n\n\\begin{aligned} &0=\\underline{U}(x,t)\\leq u^{0}(x,t)\\leq\\overline{U}(x,t), \\\\ &0=\\underline{V}(x,t)\\leq v^{0}(x,t)\\leq\\overline{V}(x,t), \\end{aligned}\n(3.11)\n\nfor $$(x,t)\\in\\Omega\\times[0,\\infty)$$. We next observe that $$\\mu _{1}\\Delta\\bar{u}+\\bar{u}[a(x)-b(x)\\bar{u}]<0$$ in Ω, $$\\bar {u}|_{\\partial\\Omega}=0$$, thus $$\\bar{u}=\\theta_{\\mu_{1},a(x)}/\\min_{x\\in\\overline{\\Omega}}b(x)$$ is a strict upper solution of the problem (3.6). Similarly, $$\\bar{v}$$ is a strict upper solution of the problem (3.8).\n\nBy monotone iteration and comparison, we obtain\n\n$$\\overline{U}^{\\star}\\ll\\bar{u}, \\qquad \\overline{V}^{\\star} \\ll\\bar{v}.$$\n(3.12)\n\nFor $$s>0$$, let $$u^{s}(x)=u(x,s)$$, $$v^{s}(x)=v(x,s)$$ for $$x\\in\\overline {\\Omega}$$. We obtain from (3.5), (3.7), (3.11), and (3.12) for $$s>0$$ sufficiently large\n\n$$u^{s}(x)\\leq\\bar{u}, \\qquad v^{s}(x)\\leq \\bar{v},$$\n(3.13)\n\nfor $$x\\in\\overline{\\Omega}$$. On the other hand for $$s>0$$, we find from the theory of parabolic equations and the strong maximum principle that $$u^{s}$$, $$v^{s}$$ are in $$C^{1}(\\overline{\\Omega})$$ and\n\n$$u^{s}(x)\\gg0,\\qquad v^{s}(x)\\gg0.$$\n(3.14)\n\nComparing (3.13) and (3.14), respectively, with (3.2) and (3.1), we obtain the conclusion of this theorem by using the first part of the proof. □\n\n## References\n\n1. Cosner, C, Laser, C: Stable coexistence states in the Volterra-Lotka competition model with diffusion. SIAM J. Appl. Math. 44, 1112-1132 (1984)\n\n2. Dancer, E: On the existence and uniqueness of positive solutions for competing species models with diffusion. Trans. Am. Math. Soc. 36, 829-859 (1991)\n\n3. Dancer, E, Guo, Z: Uniqueness and stability for solutions of competing species equations with large interactions. Commun. Appl. Nonlinear Anal. 1, 19-45 (1994)\n\n4. Leung, A: Nonlinear Systems of Partial Differential Equations: Applications to Life and Physical Sciences. World Scientific, Singapore (2009)\n\n5. Leung, A: Systems of Nonlinear Partial Equations. Applications to Biology and Engineering. Kluwer Academic, New York (1989)\n\n6. Ruan, W, Pao, C: Positive steady-state solutions of competing reaction diffusion systems. J. Differ. Equ. 117, 411-427 (1995)\n\n7. Cantrell, R, Cosner, C: Spatial Ecology via Reaction-Diffusion Equations. Wiley, New York (2003)\n\n8. He, X, Ni, W: The effects of diffusion and spatial variation in Lotka-Volterra competition-diffusion system I: heterogeneity vs. homogeneity. J. Differ. Equ. 254, 528-546 (2013)\n\n9. He, X, Ni, W: The effects of diffusion and spatial variation in Lotka-Volterra competition-diffusion system II: the general case. J. Differ. Equ. 254, 4088-4108 (2013)\n\n10. Álvarez-Caudevilla, P, Du, Y, Peng, R: Qualitative analysis of a cooperative reaction-diffusion system in a spatiotemporally degenerate environment. SIAM J. Math. Anal. 46, 499-531 (2014)\n\n11. Pao, C: Nonlinear Parabolic and Elliptic Equations. Plenum, New York (1992)\n\n## Acknowledgements\n\nThe authors are very grateful to the anonymous referees for their valuable comments and suggestions. This work is supported by the Natural Science Foundation of Shanghai, China (No. 13ZR1430100).\n\n## Author information\n\nAuthors\n\n### Corresponding author\n\nCorrespondence to Benlong Xu.\n\n### Competing interests\n\nThe authors declare that they have no competing interests.\n\n### Authors’ contributions\n\nAll the authors read and approved the final manuscript.\n\n## Rights and permissions",
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"https://boundaryvalueproblems.springeropen.com/track/article/10.1186/s13661-015-0368-7",
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.5488178,"math_prob":1.0000004,"size":7451,"snap":"2022-40-2023-06","text_gpt3_token_len":3043,"char_repetition_ratio":0.18893515,"word_repetition_ratio":0.06056338,"special_character_ratio":0.40679103,"punctuation_ratio":0.13822116,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":1.0000045,"pos_list":[0,1,2],"im_url_duplicate_count":[null,2,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-02-02T17:48:51Z\",\"WARC-Record-ID\":\"<urn:uuid:6546199c-57ef-4324-916d-27ef36668d8d>\",\"Content-Length\":\"233522\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:63dda7c7-0d21-4967-83f7-70549d18d2c1>\",\"WARC-Concurrent-To\":\"<urn:uuid:a767c067-333a-4aa9-bec4-823832d7ed2b>\",\"WARC-IP-Address\":\"146.75.32.95\",\"WARC-Target-URI\":\"https://boundaryvalueproblems.springeropen.com/articles/10.1186/s13661-015-0368-7\",\"WARC-Payload-Digest\":\"sha1:AXCKAIDCNJFSFR7IDNTEVM4DEXHUZPST\",\"WARC-Block-Digest\":\"sha1:GPAIBEMXFBGVXANL6UKSAHWFF3Y3G7P5\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-06/CC-MAIN-2023-06_segments_1674764500035.14_warc_CC-MAIN-20230202165041-20230202195041-00010.warc.gz\"}"} |
https://stacks.math.columbia.edu/tag/04DC | [
"## 29.45 Universal homeomorphisms\n\nThe following definition is really superfluous since a universal homeomorphism is really just an integral, universally injective and surjective morphism, see Lemma 29.45.5.\n\nDefinition 29.45.1. A morphisms $f : X \\to Y$ of schemes is called a universal homeomorphism if the base change $f' : Y' \\times _ Y X \\to Y'$ is a homeomorphism for every morphism $Y' \\to Y$.\n\nFirst we state the obligatory lemmas.\n\nLemma 29.45.2. The base change of a universal homeomorphism of schemes by any morphism of schemes is a universal homeomorphism.\n\nProof. This is immediate from the definition. $\\square$\n\nLemma 29.45.3. The composition of a pair of universal homeomorphisms of schemes is a universal homeomorphism.\n\nProof. Omitted. $\\square$\n\nThe following simple lemma is the key to characterizing universal homeomorphisms.\n\nLemma 29.45.4. Let $f : X \\to Y$ be a morphism of schemes. If $f$ is a homeomorphism onto a closed subset of $Y$ then $f$ is affine.\n\nProof. Let $y \\in Y$ be a point. If $y \\not\\in f(X)$, then there exists an affine neighbourhood of $y$ which is disjoint from $f(X)$. If $y \\in f(X)$, let $x \\in X$ be the unique point of $X$ mapping to $y$. Let $y \\in V$ be an affine open neighbourhood. Let $U \\subset X$ be an affine open neighbourhood of $x$ which maps into $V$. Since $f(U) \\subset V \\cap f(X)$ is open in the induced topology by our assumption on $f$ we may choose a $h \\in \\Gamma (V, \\mathcal{O}_ Y)$ such that $y \\in D(h)$ and $D(h) \\cap f(X) \\subset f(U)$. Denote $h' \\in \\Gamma (U, \\mathcal{O}_ X)$ the restriction of $f^\\sharp (h)$ to $U$. Then we see that $D(h') \\subset U$ is equal to $f^{-1}(D(h))$. In other words, every point of $Y$ has an open neighbourhood whose inverse image is affine. Thus $f$ is affine, see Lemma 29.11.3. $\\square$\n\nLemma 29.45.5. Let $f : X \\to Y$ be a morphism of schemes. The following are equivalent:\n\n1. $f$ is a universal homeomorphism, and\n\n2. $f$ is integral, universally injective and surjective.\n\nProof. Assume $f$ is a universal homeomorphism. By Lemma 29.45.4 we see that $f$ is affine. Since $f$ is clearly universally closed we see that $f$ is integral by Lemma 29.44.7. It is also clear that $f$ is universally injective and surjective.\n\nAssume $f$ is integral, universally injective and surjective. By Lemma 29.44.7 $f$ is universally closed. Since it is also universally bijective (see Lemma 29.9.4) we see that it is a universal homeomorphism. $\\square$\n\nLemma 29.45.6. Let $X$ be a scheme. The canonical closed immersion $X_{red} \\to X$ (see Schemes, Definition 26.12.5) is a universal homeomorphism.\n\nProof. Omitted. $\\square$\n\nLemma 29.45.7. Let $f : X \\to S$ and $S' \\to S$ be morphisms of schemes. Assume\n\n1. $S' \\to S$ is a closed immersion,\n\n2. $S' \\to S$ is bijective on points,\n\n3. $X \\times _ S S' \\to S'$ is a closed immersion, and\n\n4. $X \\to S$ is of finite type or $S' \\to S$ is of finite presentation.\n\nThen $f : X \\to S$ is a closed immersion.\n\nProof. Assumptions (1) and (2) imply that $S' \\to S$ is a universal homeomorphism (for example because $S_{red} = S'_{red}$ and using Lemma 29.45.6). Hence (3) implies that $X \\to S$ is homeomorphism onto a closed subset of $S$. Then $X \\to S$ is affine by Lemma 29.45.4. Let $U \\subset S$ be an affine open, say $U = \\mathop{\\mathrm{Spec}}(A)$. Then $S' = \\mathop{\\mathrm{Spec}}(A/I)$ by (1) for a locally nilpotent ideal $I$ by (2). As $f$ is affine we see that $f^{-1}(U) = \\mathop{\\mathrm{Spec}}(B)$. Assumption (4) tells us $B$ is a finite type $A$-algebra (Lemma 29.15.2) or that $I$ is finitely generated (Lemma 29.21.7). Assumption (3) is that $A/I \\to B/IB$ is surjective. From Algebra, Lemma 10.126.9 if $A \\to B$ is of finite type or Algebra, Lemma 10.20.1 if $I$ is finitely generated and hence nilpotent we deduce that $A \\to B$ is surjective. This means that $f$ is a closed immersion, see Lemma 29.2.1. $\\square$\n\n## Post a comment\n\nYour email address will not be published. Required fields are marked.\n\nIn your comment you can use Markdown and LaTeX style mathematics (enclose it like $\\pi$). A preview option is available if you wish to see how it works out (just click on the eye in the toolbar).\n\nUnfortunately JavaScript is disabled in your browser, so the comment preview function will not work.\n\nAll contributions are licensed under the GNU Free Documentation License.\n\nIn order to prevent bots from posting comments, we would like you to prove that you are human. You can do this by filling in the name of the current tag in the following input field. As a reminder, this is tag 04DC. Beware of the difference between the letter 'O' and the digit '0'."
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8478967,"math_prob":0.9983587,"size":5186,"snap":"2021-21-2021-25","text_gpt3_token_len":1615,"char_repetition_ratio":0.19895793,"word_repetition_ratio":0.3585746,"special_character_ratio":0.31237948,"punctuation_ratio":0.14891775,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9999734,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-06-24T05:39:39Z\",\"WARC-Record-ID\":\"<urn:uuid:f797be5d-4a42-4916-b849-321a6deee31a>\",\"Content-Length\":\"19167\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:865bf59d-63cc-428d-88b0-dd25b59dbd77>\",\"WARC-Concurrent-To\":\"<urn:uuid:2ac532d1-0247-4d0a-a7c9-a071485569f0>\",\"WARC-IP-Address\":\"128.59.222.85\",\"WARC-Target-URI\":\"https://stacks.math.columbia.edu/tag/04DC\",\"WARC-Payload-Digest\":\"sha1:FYDDYLBDDIJ5YFNS7R6ICDFNFZPK6FAK\",\"WARC-Block-Digest\":\"sha1:J3CX5XUY4ASRGQRUGSFXXXYUYKAFU5OE\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-25/CC-MAIN-2021-25_segments_1623488551052.94_warc_CC-MAIN-20210624045834-20210624075834-00330.warc.gz\"}"} |
https://appscrawl.com/microsoft-math-solver-for-pc-windows-7-8-10-mac-free-download/ | [
"# Microsoft Math Solver For PC / Windows 7/8/10 / Mac – Free Download",
null,
"You can now play Microsoft Math Solver for PC on a desktop/laptop running Windows XP, Windows 7, Windows 8, Windows 8.1, Windows 10 and MacOS/OS X. This can easily be done with the help of BlueStacks or Andy OS Android emulator.\n\nMicrosoft Math solver app provides help with a variety of problems including arithmetic, algebra, trigonometry, calculus, statistics, and other topics using an advanced AI powered math solver. Simply write a math problem on screen or use the camera to snap a math photo. Microsoft Math problem solver instantly recognizes the problem and helps you to solve it with ⚡FREE Step-By-Step Explanations⚡, interactive graphs, similar problems from the web and online video lectures. Quickly look up related math concepts. Get help with your homework problems and gain confidence in mastering the techniques 💯 with Microsoft Math. ⚡It is absolutely FREE and No Ads!⚡\n\nHIGHLIGHTS\n● ✏️ Write a math equation on screen as you naturally do on paper\n● 📷 Scan printed or handwritten math photo\n● ⌨️ Type and edit using advanced scientific math calculator\n● Get interactive Step-by-Step explanations 💡 & Graphing calculator 📈\n● Import images with math equations from gallery 🖼️\n● Scan and Solve Math Worksheets with multiple problems\n● 🔎Search the web for similar problems and video lectures\n● Try math word problems\n● Scan and plot x-y data tables for linear/non-linear functions\n● Learn math in your language – supports Chinese, French, German, Hindi, Italian, Japanese, Portuguese, Russian, Spanish, and many more\n\nSUPPORTED PROBLEMS\n● Elementary: arithmetic, real, complex numbers, LCM, GCD, factors, roman numerals\n● Pre-Algebra: radicals and exponents, fractions, matrices, determinants\n● Algebra: quadratic equations, system of equations, inequalities, rational expressions, linear, quadratic and exponential graphs\n● Word problems on math concepts, number theory, probability, volume, surface area\n● Basic Calculus: Summations, Limits, derivatives, integrals\n● Statistics: Mean, Median, Mode, Standard Deviation, permutations, combinations\n\nFind out more about Microsoft Math Solver app on our website 👉 Link: https://math.microsoft.com\n\nMicrosoft Math Solver For PC can be easily installed and used on a desktop computer or laptop running Windows XP, Windows 7, Windows 8, Windows 8.1, Windows 10 and a Macbook, iMac running Mac OS X. This will be done using an Android emulator. To install Microsoft Math Solver For PC, we will use BlueStacks app player. The method listed below is set to help you get Microsoft Math Solver For PC. Go ahead and get it done now.",
null,
"Download and use Microsoft Math Solver on your PC & Mac using an Android Emulator.\n\n### Step to Step Guide / Microsoft Math Solver For PC:\n\nMicrosoft Math Solver by Microsoft Corporation,",
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"http://lh3.googleusercontent.com/IynxIYziGff1xaEiuAEZirWVMrL5W0QpSf0d6favDk3IeOB7Cg8PmsX40DSFgtR7Dw=w300",
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"http://lh3.googleusercontent.com/IynxIYziGff1xaEiuAEZirWVMrL5W0QpSf0d6favDk3IeOB7Cg8PmsX40DSFgtR7Dw=w300",
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"http://appscrawl.com/wp-content/uploads/2017/03/gp_logo-1.png",
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8122217,"math_prob":0.7409282,"size":3749,"snap":"2020-45-2020-50","text_gpt3_token_len":858,"char_repetition_ratio":0.15006675,"word_repetition_ratio":0.05901639,"special_character_ratio":0.21259002,"punctuation_ratio":0.14265129,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9815612,"pos_list":[0,1,2,3,4,5,6],"im_url_duplicate_count":[null,2,null,2,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-11-24T23:37:24Z\",\"WARC-Record-ID\":\"<urn:uuid:5130a00b-cad3-423f-b1ab-067236e01b54>\",\"Content-Length\":\"41655\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:0e8c02d6-30cf-480c-9ddf-2fc2f67a677f>\",\"WARC-Concurrent-To\":\"<urn:uuid:333c8071-35e9-42ad-abe6-9eb4751905ca>\",\"WARC-IP-Address\":\"199.188.204.205\",\"WARC-Target-URI\":\"https://appscrawl.com/microsoft-math-solver-for-pc-windows-7-8-10-mac-free-download/\",\"WARC-Payload-Digest\":\"sha1:X4CJ2DTMDMVPW5VS26OF2ABVEMIJFWBR\",\"WARC-Block-Digest\":\"sha1:AM6UWKYLUYORDQEKHREKC6BHQK3V22Q2\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-50/CC-MAIN-2020-50_segments_1606141177607.13_warc_CC-MAIN-20201124224124-20201125014124-00610.warc.gz\"}"} |
https://transform.softwareunderground.org/2022-gstools/binary | [
"Tutorials",
null,
"# binary fields\n\n%matplotlib widget\nimport matplotlib.pyplot as plt\nplt.ioff()\n# turn of warnings\nimport warnings\nwarnings.filterwarnings('ignore')\n\nHere we transform a field to a binary field with only two values. The dividing value is the mean by default and the upper and lower values are derived to preserve the variance.\n\nSee transform.binary\n\nimport gstools as gs\n\n# structured field with a size of 100x100 and a grid-size of 1x1\nx = y = range(100)\nmodel = gs.Gaussian(dim=2, var=1, len_scale=10)\nsrf = gs.SRF(model, seed=20170519)\nsrf.structured([x, y])\nsrf.transform(\"binary\")\nsrf.plot()"
] | [
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"https://transform.softwareunderground.org/build/_assets/jupyter-7WANWHPN.svg",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.69593465,"math_prob":0.97600514,"size":588,"snap":"2022-40-2023-06","text_gpt3_token_len":157,"char_repetition_ratio":0.12842466,"word_repetition_ratio":0.0,"special_character_ratio":0.26870748,"punctuation_ratio":0.13043478,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9931765,"pos_list":[0,1,2],"im_url_duplicate_count":[null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-01-30T22:12:37Z\",\"WARC-Record-ID\":\"<urn:uuid:f5547ab4-18d9-48cf-857f-8069b35044e4>\",\"Content-Length\":\"83309\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:69239852-32ea-4b4b-aac0-3ba867649bbf>\",\"WARC-Concurrent-To\":\"<urn:uuid:c94663fd-bd4c-4d78-abd1-30dc805b1278>\",\"WARC-IP-Address\":\"76.76.21.98\",\"WARC-Target-URI\":\"https://transform.softwareunderground.org/2022-gstools/binary\",\"WARC-Payload-Digest\":\"sha1:X4TL6KSBE2UWRPD46YMRHOATZBAR4RIF\",\"WARC-Block-Digest\":\"sha1:DYASVLIXSTA2JDONIT3K5GBPPHC5OZWU\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-06/CC-MAIN-2023-06_segments_1674764499829.29_warc_CC-MAIN-20230130201044-20230130231044-00813.warc.gz\"}"} |
http://entercad.ru/acadauto.en/ex_majorradius.htm | [
"```Sub Example_MajorRadius()\n' This example creates an Ellipse in model space and displays\n' both the Major radius and the Minor radius of the new Ellipse\n\nDim majAxis(0 To 2) As Double, center(0 To 2) As Double\n\n' Create an ellipse in model space\ncenter(0) = 5: center(1) = 5: center(2) = 0\nmajAxis(0) = 10: majAxis(1) = 20: majAxis(2) = 0"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.5215217,"math_prob":0.97707987,"size":766,"snap":"2020-45-2020-50","text_gpt3_token_len":213,"char_repetition_ratio":0.15223098,"word_repetition_ratio":0.075630255,"special_character_ratio":0.26501307,"punctuation_ratio":0.120567374,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.98504937,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-11-24T23:37:37Z\",\"WARC-Record-ID\":\"<urn:uuid:dcd4584d-fcfd-4fde-b6d4-6a3839c6f8fc>\",\"Content-Length\":\"9205\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:741cd6f0-e64c-4687-8aaa-9b86eab39c3a>\",\"WARC-Concurrent-To\":\"<urn:uuid:13050e50-48f2-41a6-96f1-c481296dc74f>\",\"WARC-IP-Address\":\"45.89.69.168\",\"WARC-Target-URI\":\"http://entercad.ru/acadauto.en/ex_majorradius.htm\",\"WARC-Payload-Digest\":\"sha1:V64HJJH5FYIW4LH2CTASVUCYSVG26BZV\",\"WARC-Block-Digest\":\"sha1:CRCM4OWBP3YFHHC2C5CFNOH2JT3DC5EK\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-50/CC-MAIN-2020-50_segments_1606141177607.13_warc_CC-MAIN-20201124224124-20201125014124-00299.warc.gz\"}"} |
https://www.colorhexa.com/00e823 | [
"# #00e823 Color Information\n\nIn a RGB color space, hex #00e823 is composed of 0% red, 91% green and 13.7% blue. Whereas in a CMYK color space, it is composed of 100% cyan, 0% magenta, 84.9% yellow and 9% black. It has a hue angle of 129.1 degrees, a saturation of 100% and a lightness of 45.5%. #00e823 color hex could be obtained by blending #00ff46 with #00d100. Closest websafe color is: #00ff33.\n\n• R 0\n• G 91\n• B 14\nRGB color chart\n• C 100\n• M 0\n• Y 85\n• K 9\nCMYK color chart\n\n#00e823 color description : Pure (or mostly pure) lime green.\n\n# #00e823 Color Conversion\n\nThe hexadecimal color #00e823 has RGB values of R:0, G:232, B:35 and CMYK values of C:1, M:0, Y:0.85, K:0.09. Its decimal value is 59427.\n\nHex triplet RGB Decimal 00e823 `#00e823` 0, 232, 35 `rgb(0,232,35)` 0, 91, 13.7 `rgb(0%,91%,13.7%)` 100, 0, 85, 9 129.1°, 100, 45.5 `hsl(129.1,100%,45.5%)` 129.1°, 100, 91 00ff33 `#00ff33`\nCIE-LAB 80.645, -79.354, 72.876 29.158, 57.831, 11.216 0.297, 0.589, 57.831 80.645, 107.74, 137.437 80.645, -75.971, 95.566 76.047, -64.641, 44.488 00000000, 11101000, 00100011\n\n# Color Schemes with #00e823\n\n• #00e823\n``#00e823` `rgb(0,232,35)``\n• #e800c5\n``#e800c5` `rgb(232,0,197)``\nComplementary Color\n• #51e800\n``#51e800` `rgb(81,232,0)``\n• #00e823\n``#00e823` `rgb(0,232,35)``\n• #00e897\n``#00e897` `rgb(0,232,151)``\nAnalogous Color\n• #e80051\n``#e80051` `rgb(232,0,81)``\n• #00e823\n``#00e823` `rgb(0,232,35)``\n• #9700e8\n``#9700e8` `rgb(151,0,232)``\nSplit Complementary Color\n• #e82300\n``#e82300` `rgb(232,35,0)``\n• #00e823\n``#00e823` `rgb(0,232,35)``\n• #2300e8\n``#2300e8` `rgb(35,0,232)``\n• #c5e800\n``#c5e800` `rgb(197,232,0)``\n• #00e823\n``#00e823` `rgb(0,232,35)``\n• #2300e8\n``#2300e8` `rgb(35,0,232)``\n• #e800c5\n``#e800c5` `rgb(232,0,197)``\n• #009c17\n``#009c17` `rgb(0,156,23)``\n• #00b51b\n``#00b51b` `rgb(0,181,27)``\n• #00cf1f\n``#00cf1f` `rgb(0,207,31)``\n• #00e823\n``#00e823` `rgb(0,232,35)``\n• #02ff29\n``#02ff29` `rgb(2,255,41)``\n• #1cff3e\n``#1cff3e` `rgb(28,255,62)``\n• #36ff54\n``#36ff54` `rgb(54,255,84)``\nMonochromatic Color\n\n# Alternatives to #00e823\n\nBelow, you can see some colors close to #00e823. Having a set of related colors can be useful if you need an inspirational alternative to your original color choice.\n\n• #17e800\n``#17e800` `rgb(23,232,0)``\n• #04e800\n``#04e800` `rgb(4,232,0)``\n• #00e810\n``#00e810` `rgb(0,232,16)``\n• #00e823\n``#00e823` `rgb(0,232,35)``\n• #00e836\n``#00e836` `rgb(0,232,54)``\n• #00e84a\n``#00e84a` `rgb(0,232,74)``\n• #00e85d\n``#00e85d` `rgb(0,232,93)``\nSimilar Colors\n\n# #00e823 Preview\n\nThis text has a font color of #00e823.\n\n``<span style=\"color:#00e823;\">Text here</span>``\n#00e823 background color\n\nThis paragraph has a background color of #00e823.\n\n``<p style=\"background-color:#00e823;\">Content here</p>``\n#00e823 border color\n\nThis element has a border color of #00e823.\n\n``<div style=\"border:1px solid #00e823;\">Content here</div>``\nCSS codes\n``.text {color:#00e823;}``\n``.background {background-color:#00e823;}``\n``.border {border:1px solid #00e823;}``\n\n# Shades and Tints of #00e823\n\nA shade is achieved by adding black to any pure hue, while a tint is created by mixing white to any pure color. In this example, #001002 is the darkest color, while #fcfffc is the lightest one.\n\n• #001002\n``#001002` `rgb(0,16,2)``\n• #002405\n``#002405` `rgb(0,36,5)``\n• #003708\n``#003708` `rgb(0,55,8)``\n• #004b0b\n``#004b0b` `rgb(0,75,11)``\n• #005f0e\n``#005f0e` `rgb(0,95,14)``\n• #007211\n``#007211` `rgb(0,114,17)``\n• #008614\n``#008614` `rgb(0,134,20)``\n• #009a17\n``#009a17` `rgb(0,154,23)``\n``#00ad1a` `rgb(0,173,26)``\n• #00c11d\n``#00c11d` `rgb(0,193,29)``\n• #00d420\n``#00d420` `rgb(0,212,32)``\n• #00e823\n``#00e823` `rgb(0,232,35)``\n• #00fc26\n``#00fc26` `rgb(0,252,38)``\n• #10ff34\n``#10ff34` `rgb(16,255,52)``\n• #24ff45\n``#24ff45` `rgb(36,255,69)``\n• #37ff56\n``#37ff56` `rgb(55,255,86)``\n• #4bff66\n``#4bff66` `rgb(75,255,102)``\n• #5fff77\n``#5fff77` `rgb(95,255,119)``\n• #72ff88\n``#72ff88` `rgb(114,255,136)``\n• #86ff98\n``#86ff98` `rgb(134,255,152)``\n• #9affa9\n``#9affa9` `rgb(154,255,169)``\n``#adffba` `rgb(173,255,186)``\n• #c1ffca\n``#c1ffca` `rgb(193,255,202)``\n• #d4ffdb\n``#d4ffdb` `rgb(212,255,219)``\n• #e8ffeb\n``#e8ffeb` `rgb(232,255,235)``\n• #fcfffc\n``#fcfffc` `rgb(252,255,252)``\nTint Color Variation\n\n# Tones of #00e823\n\nA tone is produced by adding gray to any pure hue. In this case, #6b7d6e is the less saturated color, while #00e823 is the most saturated one.\n\n• #6b7d6e\n``#6b7d6e` `rgb(107,125,110)``\n• #628668\n``#628668` `rgb(98,134,104)``\n• #598f61\n``#598f61` `rgb(89,143,97)``\n• #50985b\n``#50985b` `rgb(80,152,91)``\n• #47a155\n``#47a155` `rgb(71,161,85)``\n• #3eaa4f\n``#3eaa4f` `rgb(62,170,79)``\n• #36b248\n``#36b248` `rgb(54,178,72)``\n• #2dbb42\n``#2dbb42` `rgb(45,187,66)``\n• #24c43c\n``#24c43c` `rgb(36,196,60)``\n• #1bcd36\n``#1bcd36` `rgb(27,205,54)``\n• #12d62f\n``#12d62f` `rgb(18,214,47)``\n• #09df29\n``#09df29` `rgb(9,223,41)``\n• #00e823\n``#00e823` `rgb(0,232,35)``\nTone Color Variation\n\n# Color Blindness Simulator\n\nBelow, you can see how #00e823 is perceived by people affected by a color vision deficiency. This can be useful if you need to ensure your color combinations are accessible to color-blind users.\n\nMonochromacy\n• Achromatopsia 0.005% of the population\n• Atypical Achromatopsia 0.001% of the population\nDichromacy\n• Protanopia 1% of men\n• Deuteranopia 1% of men\n• Tritanopia 0.001% of the population\nTrichromacy\n• Protanomaly 1% of men, 0.01% of women\n• Deuteranomaly 6% of men, 0.4% of women\n• Tritanomaly 0.01% of the population"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.50097644,"math_prob":0.8838481,"size":3666,"snap":"2023-40-2023-50","text_gpt3_token_len":1618,"char_repetition_ratio":0.13517204,"word_repetition_ratio":0.007352941,"special_character_ratio":0.55591923,"punctuation_ratio":0.22866894,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9924742,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-11-28T17:00:04Z\",\"WARC-Record-ID\":\"<urn:uuid:4b34eeed-b0da-4098-8fb9-629f27d1a6cf>\",\"Content-Length\":\"36162\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:0df36871-c404-469d-9ec9-61d759c256dc>\",\"WARC-Concurrent-To\":\"<urn:uuid:7e722ac7-4cfa-4c83-b013-e80acb84a5d1>\",\"WARC-IP-Address\":\"178.32.117.56\",\"WARC-Target-URI\":\"https://www.colorhexa.com/00e823\",\"WARC-Payload-Digest\":\"sha1:5TTUA7UXWW327TB6EE6VA5UTEEHDOK3L\",\"WARC-Block-Digest\":\"sha1:T5JRQKHV5HICJ4D3DKSJTMUCYYBYEMDM\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-50/CC-MAIN-2023-50_segments_1700679099892.46_warc_CC-MAIN-20231128151412-20231128181412-00498.warc.gz\"}"} |
https://www.onlinemath4all.com/trigonometry-word-problems-with-solutions.html | [
"# TRIGONOMETRY WORD PROBLEMS WITH SOLUTIONS\n\nTrigonometry Word Problems with Solutions :\n\nIn this section, you will learn how to solve word problems in trigonometry step by step.\n\n## Trigonometry Word Problems with Solutions\n\nProblem 1 :\n\nThe angle of elevation of the top of the building at a distance of 50 m from its foot on a horizontal plane is found to be 60 degree. Find the height of the building.\n\nSolution :\n\nDraw a sketch.",
null,
"Here, AB represents height of the building, BC represents distance of the building from the point of observation.\n\nIn the right triangle ABC, the side which is opposite to the angle 60 degree is known as opposite side (AB), the side which is opposite to 90 degree is called hypotenuse side (AC) and the remaining side is called adjacent side (BC).\n\nNow we need to find the length of the side AB.\n\ntan 60° = AB/BC\n\n√3 = AB/50\n\n√3 x 50 = AB\n\nAB = 50√3\n\nApproximate value of √3 is 1.732\n\nAB = 50 (1.732)\n\nAB = 86.6 m\n\nSo, the height of the building is 86.6 m.\n\nProblem 2 :\n\nA ladder placed against a wall such that it reaches the top of the wall of height 6 m and the ladder is inclined at an angle of 60 degree. Find how far the ladder is from the foot of the wall.\n\nSolution :\n\nDraw a sketch.",
null,
"Here AB represents height of the wall, BC represents the distance between the wall and the foot of the ladder and AC represents the length of the ladder.\n\nIn the right triangle ABC, the side which is opposite to angle 60 degree is known as opposite side (AB), the side which is opposite to 90 degree is called hypotenuse side (AC) and remaining side is called adjacent side (BC).\n\nNow, we need to find the distance between foot of the ladder and the wall. That is, we have to find the length of BC.\n\ntan θ = Opposite side/Adjacent side\n\ntan60° = AB/BC\n\n√3 = 6/BC\n\nBC = 6/√3\n\nBC = (6/√3) x (√3/√3)\n\nBC = (6√3)/3\n\nBC = 2√3\n\nApproximate value of √3 is 1.732\n\nBC = 2 (1.732)\n\nBC = 3.464 m\n\nSo, the distance between foot of the ladder and the wall is 3.464 m.\n\nProblem 3 :\n\nA string of a kite is 100 meters long and it makes an angle of 60° with horizontal. Find the height of the kite,assuming that there is no slack in the string.\n\nSolution :\n\nDraw a sketch.",
null,
"Here AB represents height of kite from the ground, BC represents the distance of kite from the point of observation.\n\nIn the right triangle ABC the side which is opposite to angle 60 degree is known as opposite side (AB), the side which is opposite to 90 degree is called hypotenuse side (AC) and remaining side is called adjacent side (BC).\n\nNow we need to find the height of the side AB.\n\nSin θ = Opposite side/Hypotenuse side\n\nsinθ = AB/AC\n\nsin 60° = AB/100\n\n√3/2 = AB/100\n\n(√3/2) x 100 = AB\n\nAB = 50 √3 m\n\nSo, the height of kite from the ground 50 √3 m.\n\nProblem 4 :\n\nFrom the top of the tower 30 m height a man is observing the base of a tree at an angle of depression measuring 30 degree. Find the distance between the tree and the tower.\n\nSolution :\n\nDraw a sketch.",
null,
"Here AB represents height of the tower, BC represents the distance between foot of the tower and the foot of the tree.\n\nNow we need to find the distance between foot of the tower and the foot of the tree (BC).\n\ntan θ = Opposite side/Adjacent side\n\ntan 30° = AB/BC\n\n1/√3 = 30/BC\n\nBC = 30√3\n\nApproximate value of √3 is 1.732\n\nBC = 30 (1.732)\n\nBC = 81.96 m\n\nSo, the distance between the tree and the tower is 51.96 m.\n\nProblem 5 :\n\nA man wants to determine the height of a light house. He measured the angle at A and found that tan A = 3/4. What is the height of the light house if A is 40 m from the base?\n\nSolution :\n\nDraw a sketch.",
null,
"Here BC represents height of the light house, AB represents the distance between the light house from the point of observation.\n\nIn the right triangle ABC the side which is opposite to the angle A is known as opposite side (BC), the side which is opposite to 90 degree is called hypotenuse side (AC) and remaining side is called adjacent side (AB).\n\nNow we need to find the height of the light house (BC).\n\ntanA = BC/AB\n\nGiven : tanA = 3/4\n\n3/4 = BC/40\n\n3 x 40 = BC x 4\n\nBC = (3 x 40)/4\n\nBC = (3 x 10)\n\nBC = 30 m\n\nSo, the height of the light house is 30 m.\n\nProblem 6 :\n\nA man wants to determine the height of a light house. He A ladder is leaning against a vertical wall makes an angle of 20° with the ground. The foot of the ladder is 3 m from the wall.Find the length of ladder.\n\nSolution :\n\nDraw a sketch.",
null,
"Here AB represents height of the wall, BC represents the distance of the wall from the foot of the ladder.\n\nIn the right triangle ABC the side which is opposite to the angle 20 degree is known as opposite side (AB),the side which is opposite to 90 degree is called hypotenuse side (AC) and remaining side is called adjacent side (BC).\n\nNow we need to find the length of the ladder (AC).\n\nCos θ = Adjacent side/Hypotenuse side\n\nCos θ = BC/AC\n\nCos 20° = 3/AC\n\n0.9396 = 3/AC\n\nAC = 3/0.9396\n\nAC = 3.192\n\nSo, the length of the ladder is 3.192 m.\n\nProblem 7 :\n\nA kite flying at a height of 65 m is attached to a string inclined at 31° to the horizontal. What is the length of string ?\n\nSolution :\n\nDraw a sketch.",
null,
"Here AB represents height of the kite. In the right triangle ABC the side which is opposite to angle 31 degree is known as opposite side (AB), the side which is opposite to 90 degree is called hypotenuse side (AC) and the remaining side is called adjacent side (BC).\n\nNow we need to find the length of the string AC.\n\nSin θ = Opposite side/Hypotenuse side\n\nSin θ = AB/AC\n\nSin 31° = AB/AC\n\n0.5150 = 65/AC\n\nAC = 65/0.5150\n\nAC = 126.2 m\n\nHence, the length of the string is 126.2 m.\n\nProblem 8 :\n\nThe length of a string between a kite and a point on the ground is 90 m. If the string is making an angle θ with the level ground such that tan θ = 15/8, how high will the kite be ?\n\nSolution :\n\nDraw a sketch.",
null,
"Here AB represents height of the balloon from the ground. In the right triangle ABC the side which is opposite to angle θ is known as opposite side (AB), the side which is opposite to 90 degree is called hypotenuse side (AC) and remaining side is called adjacent side (BC).\n\nNow we need to find the length of the side AB.\n\nTan θ = 15/8 --------> Cot θ = 8/15\n\nCsc θ = √(1+ cot²θ)\n\nCsc θ = √(1 + 64/225)\n\nCsc θ = √(225 + 64)/225\n\nCsc θ = √289/225\n\nCsc θ = 17/15 -------> Sin θ = 15/17\n\nBut, sin θ = Opposite side/Hypotenuse side = AB/AC\n\nAB/AC = 15/17\n\nAB/90 = 15/17\n\nAB = (15 x 90)/17\n\nAB = 79.41\n\nSo, the height of the tower is 79.41 m.\n\nProblem 9 :\n\nAn aeroplane is observed to be approaching the airpoint. It is at a distance of 12 km from the point of observation and makes an angle of elevation of 50 degree. Find the height above the ground.\n\nSolution :\n\nDraw a sketch.",
null,
"Here AB represents height of the airplane from the ground.In the right triangle ABC the side which is opposite to angle 50 degree is known as opposite side (AB), the side which is opposite to 90 degree is called hypotenuse side (AC) and remaining side is called adjacent side (BC).\n\nNow we need to find the length of the side AB.\n\nFrom the figure given above, AB stands for the height of the aeroplane above the ground.\n\nsin θ = Opposite side/Hypotenuse side\n\nsin 50° = AB/AC\n\n0.7660 = h/12\n\n0.7660 x 12 = h\n\nh = 9.192 km\n\nSo, the height of the aeroplane above the ground is 9.192 km.\n\nProblem 10 :\n\nA balloon is connected to a meteorological station by a cable of length 200 m inclined at 60 degree angle . Find the height of the balloon from the ground. (Imagine that there is no slack in the cable)\n\nSolution :\n\nDraw a sketch.",
null,
"Here AB represents height of the balloon from the ground. In the right triangle ABC the side which is opposite to angle 60 degree is known as opposite side (AB), the side which is opposite to 90 degree is called hypotenuse (AC) and the remaining side is called as adjacent side (BC).\n\nNow we need to find the length of the side AB.\n\nFrom the figure given above, AB stands for the height of the balloon above the ground.\n\nsin θ = Opposite side/Hypotenuse side\n\nsin θ = AB/AC\n\nsin 60° = AB/200\n\n√3/2 = AB/200\n\nAB = (√3/2) x 200\n\nAB = 100√3\n\nApproximate value of √3 is 1.732\n\nAB = 100 (1.732)\n\nAB = 173.2 m\n\nSo, the height of the balloon from the ground is 173.2 m.",
null,
"After having gone through the stuff given above, we hope that the students would have understood, how to solve word problems in trigonometry.\n\nApart from the stuff given in this section, if you need any other stuff in math, please use our google custom search here.\n\nYou can also visit our following web pages on different stuff in math.\n\nWORD PROBLEMS\n\nWord problems on simple equations\n\nWord problems on linear equations\n\nAlgebra word problems\n\nWord problems on trains\n\nArea and perimeter word problems\n\nWord problems on direct variation and inverse variation\n\nWord problems on unit price\n\nWord problems on unit rate\n\nWord problems on comparing rates\n\nConverting customary units word problems\n\nConverting metric units word problems\n\nWord problems on simple interest\n\nWord problems on compound interest\n\nWord problems on types of angles\n\nComplementary and supplementary angles word problems\n\nDouble facts word problems\n\nTrigonometry word problems\n\nPercentage word problems\n\nProfit and loss word problems\n\nMarkup and markdown word problems\n\nDecimal word problems\n\nWord problems on fractions\n\nWord problems on mixed fractrions\n\nOne step equation word problems\n\nLinear inequalities word problems\n\nRatio and proportion word problems\n\nTime and work word problems\n\nWord problems on sets and venn diagrams\n\nWord problems on ages\n\nPythagorean theorem word problems\n\nPercent of a number word problems\n\nWord problems on constant speed\n\nWord problems on average speed\n\nWord problems on sum of the angles of a triangle is 180 degree\n\nOTHER TOPICS\n\nProfit and loss shortcuts\n\nPercentage shortcuts\n\nTimes table shortcuts\n\nTime, speed and distance shortcuts\n\nRatio and proportion shortcuts\n\nDomain and range of rational functions\n\nDomain and range of rational functions with holes\n\nGraphing rational functions\n\nGraphing rational functions with holes\n\nConverting repeating decimals in to fractions\n\nDecimal representation of rational numbers\n\nFinding square root using long division\n\nL.C.M method to solve time and work problems\n\nTranslating the word problems in to algebraic expressions\n\nRemainder when 2 power 256 is divided by 17\n\nRemainder when 17 power 23 is divided by 16\n\nSum of all three digit numbers divisible by 6\n\nSum of all three digit numbers divisible by 7\n\nSum of all three digit numbers divisible by 8\n\nSum of all three digit numbers formed using 1, 3, 4\n\nSum of all three four digit numbers formed with non zero digits\n\nSum of all three four digit numbers formed using 0, 1, 2, 3\n\nSum of all three four digit numbers formed using 1, 2, 5, 6",
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https://programming.arora-aditya.com/leetcode/tree/701.-insert-into-a-binary-search-tree | [
"# Approach 1: Recursively insert into left or right parts\n\n`# Definition for a binary tree node.# class TreeNode(object):# def __init__(self, x):# self.val = x# self.left = None# self.right = Noneclass Solution(object): def insertIntoBST(self, root, val): \"\"\" :type root: TreeNode :type val: int :rtype: TreeNode \"\"\" if root == None: return TreeNode(val) if val > root.val: root.right = self.insertIntoBST(root.right, val) else: root.left = self.insertIntoBST(root.left, val) return root`\n\nTime Complexity: O(logN) assuming balanced BST (Otherwise O(N) worst case where N is number of nodes)\n\nSpace Complexity: O(M) height of the stack (recursive call)\n\n# Approach 2: Iterative Approach 1\n\n`# Definition for a binary tree node.# class TreeNode(object):# def __init__(self, x):# self.val = x# self.left = None# self.right = Noneclass Solution(object): def insertIntoBST(self, root, val): \"\"\" https://leetcode.com/problems/insert-into-a-binary-search-tree/description/ :type root: TreeNode :type val: int :rtype: TreeNode \"\"\" parser = root prevParser = root while parser: if val > parser.val: prevParser = parser parser = parser.right else: prevParser = parser parser = parser.left if val > prevParser.val: prevParser.right = TreeNode(val) else: prevParser.left = TreeNode(val) return root`\n\nWe iterate through the tree and each time eliminate half the tree based on the value of the current node we are on. If the value to be inserted is greater than current node's value we move to the right tree and vice versa. By the time we finish iterating like this we reach the position where the node is supposed to inserted. We insert it in it's position using the `TreeNode prevParser` which stores the position of the parser one iteration behind i.e. the parent node\n\nTime Complexity: O(logN) assuming balanced BST (Otherwise O(N) worst case where N is number of nodes)\n\nSpace Complexity: O(1)"
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https://math.answers.com/other-math/What_is_half_of_28 | [
"",
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"",
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"",
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"0\n\n# What is half of 28?\n\nHalf of 28 Is 14. Or do 14 + 14 = 28 plus, 2x14",
null,
"Study guides\n\n20 cards\n\n## A number a power of a variable or a product of the two is a monomial while a polynomial is the of monomials\n\n➡️\nSee all cards\n3.75\n859 Reviews\n\nno idea what it is im just 9 but solved the hardest question about if there are 600 dollars then how much pennies are there",
null,
"2x14 = 28 or 14+14=28",
null,
"14",
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"14",
null,
"14",
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"14",
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"fourteen",
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"20",
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"Earn +20 pts",
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https://www.degruyter.com/view/j/gmj.ahead-of-print/gmj-2017-0062/gmj-2017-0062.xml | [
"Show Summary Details\nMore options …",
null,
"Georgian Mathematical Journal\n\nEditor-in-Chief: Kiguradze, Ivan / Buchukuri, T.\n\nEditorial Board: Kvinikadze, M. / Bantsuri, R. / Baues, Hans-Joachim / Besov, O.V. / Bojarski, B. / Duduchava, R. / Engelbert, Hans-Jürgen / Gamkrelidze, R. / Gubeladze, J. / Hirzebruch, F. / Inassaridze, Hvedri / Jibladze, M. / Kadeishvili, T. / Kegel, Otto H. / Kharazishvili, Alexander / Kharibegashvili, S. / Khmaladze, E. / Kiguradze, Tariel / Kokilashvili, V. / Krushkal, S. I. / Kurzweil, J. / Kwapien, S. / Lerche, Hans Rudolf / Mawhin, Jean / Ricci, P.E. / Tarieladze, V. / Triebel, Hans / Vakhania, N. / Zanolin, Fabio\n\nIMPACT FACTOR 2018: 0.551\n\nCiteScore 2018: 0.52\n\nSCImago Journal Rank (SJR) 2018: 0.320\nSource Normalized Impact per Paper (SNIP) 2018: 0.711\n\nMathematical Citation Quotient (MCQ) 2018: 0.27\n\nOnline\nISSN\n1572-9176\nSee all formats and pricing\nMore options …\n\nA Tauberian theorem for the generalized Nörlund summability method\n\nİbrahim Çanak",
null,
"/ Naim L. Braha\n• Department of Computer Sciences and Applied Mathematics, College Vizioni per Arsim, Rr, Ahmet Kaciku, Ferizaj, 70000, Kosovo\n• Email\n• Other articles by this author:\n• De Gruyter OnlineGoogle Scholar\n/ Ümit Totur",
null,
"Published Online: 2018-01-10 | DOI: https://doi.org/10.1515/gmj-2017-0062\n\nAbstract\n\nLet $\\left({p}_{n}\\right)$ and $\\left({q}_{n}\\right)$ be any two non-negative real sequences, with ${R}_{n}:={\\sum }_{k=0}^{n}{p}_{k}{q}_{n-k}\\ne 0$ ($n\\in ℕ$). Let ${\\sum }_{k=0}^{\\mathrm{\\infty }}{a}_{k}$ be a series of real or complex numbers with partial sums $\\left({s}_{n}\\right)$, and set ${t}_{n}^{p,q}:=\\frac{1}{{R}_{n}}{\\sum }_{k=0}^{n}{p}_{k}{q}_{n-k}{s}_{k}$ for $n\\in ℕ$. In this paper, we present the necessary and sufficient conditions under which the existence of the limit ${lim}_{n\\to \\mathrm{\\infty }}{s}_{n}=L$ follows from that of ${lim}_{n\\to \\mathrm{\\infty }}{t}_{n}^{p,q}=L$. These conditions are one-sided or two-sided if $\\left({s}_{n}\\right)$ is a sequence of real or complex numbers, respectively.\n\nMSC 2010: 40G15; 41A36\n\nReferences\n\n• \n\nD. Borwein, On products of sequences, J. Lond. Math. Soc. 33 (1958), 352–357. Google Scholar\n\n• \n\nI. Çanak and Y. Erdem, On Tauberian theorems for $\\left(A\\right)\\left(C,\\alpha \\right)$ summability method, Appl. Math. Comput. 218 (2011), no. 6, 2829–2836.\n\n• \n\nI. Çanak and U. Totur, Extended Tauberian theorem for the weighted mean method of summability, Ukrainian Math. J. 65 (2013), no. 7, 1032–1041.\n\n• \n\nI. Çanak and U. Totur, A theorem for the $\\left(J,p\\right)$ summability method, Acta Math. Hungar. 145 (2015), no. 1, 220–228. Google Scholar\n\n• \n\nY. Erdem, I. Çanak and B. P. Allahverdiev, Two theorems on the product of Abel and Cesàro summability methods, C. R. Acad. Bulgare Sci. 68 (2015), no. 3, 287–294. Google Scholar\n\n• \n\nG. H. Hardy, Divergent Series, Clarendon Press, Oxford, 1949. Google Scholar\n\n• \n\nR. Kiesel, General Nörlund transforms and power series methods, Math. Z. 214 (1993), no. 2, 273–286.\n\n• \n\nR. Kiesel and U. Stadtmüller, Tauberian- and convexity theorems for certain $\\left(N,p,q\\right)$-means, Canad. J. Math. 46 (1994), no. 5, 982–994. Google Scholar\n\n• \n\nE. Landau, Über die Bedeutung einiger neuen Grenzwertsätze der Herren Hardy und Axel, Prac. Mat.-Fiz. 21 (1910), 97–177. Google Scholar\n\n• \n\nF. Móricz and B. E. Rhoades, Necessary and sufficient Tauberian conditions for certain weighted mean methods of summability, Acta Math. Hungar. 66 (1995), no. 1–2, 105–111.\n\n• \n\nR. Schmidt, Über divergente Folgen und lineare Mittelbildungen, Math. Z. 22 (1925), no. 1, 89–152.\n\n• \n\nU. Stadtmüller and A. Tali, On certain families of generalized Nörlund methods and power series methods, J. Math. Anal. Appl. 238 (1999), no. 1, 44–66.\n\n• \n\nU. Totur and I. Çanak, Some general Tauberian conditions for the weighted mean summability method, Comput. Math. Appl. 63 (2012), no. 5, 999–1006.\n\nAccepted: 2016-05-23\n\nPublished Online: 2018-01-10\n\nCitation Information: Georgian Mathematical Journal, ISSN (Online) 1572-9176, ISSN (Print) 1072-947X,\n\nExport Citation\n\n© 2018 Walter de Gruyter GmbH, Berlin/Boston.",
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https://projecteuclid.org/euclid.agt/1511895851 | [
"## Algebraic & Geometric Topology\n\n### Near-symplectic $2n$–manifolds\n\nRamón Vera\n\n#### Abstract\n\nWe give a generalization of the concept of near-symplectic structures to $2n$ dimensions. According to our definition, a closed $2$–form on a $2n$–manifold $M$ is near-symplectic if it is symplectic outside a submanifold $Z$ of codimension $3$ where $ωn−1$ vanishes. We depict how this notion relates to near-symplectic $4$–manifolds and broken Lefschetz fibrations via some examples. We define a generalized broken Lefschetz fibration as a singular map with indefinite folds and Lefschetz-type singularities. We show that, given such a map on a $2n$–manifold over a symplectic base of codimension $2$, the total space carries such a near-symplectic structure whose singular locus corresponds precisely to the singularity set of the fibration. A second part studies the geometry around the codimension-$3$ singular locus $Z$. We describe a splitting property of the normal bundle $NZ$ that is also present in dimension four. A tubular neighbourhood theorem for $Z$ is provided, which has a Darboux-type theorem for near-symplectic forms as a corollary.\n\n#### Article information\n\nSource\nAlgebr. Geom. Topol., Volume 16, Number 3 (2016), 1403-1426.\n\nDates\nReceived: 12 August 2014\nRevised: 19 August 2015\nAccepted: 3 October 2015\nFirst available in Project Euclid: 28 November 2017\n\nPermanent link to this document\nhttps://projecteuclid.org/euclid.agt/1511895851\n\nDigital Object Identifier\ndoi:10.2140/agt.2016.16.1403\n\nMathematical Reviews number (MathSciNet)\nMR3523044\n\nZentralblatt MATH identifier\n1342.53110\n\n#### Citation\n\nVera, Ramón. Near-symplectic $2n$–manifolds. Algebr. Geom. Topol. 16 (2016), no. 3, 1403--1426. doi:10.2140/agt.2016.16.1403. https://projecteuclid.org/euclid.agt/1511895851"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.79918325,"math_prob":0.92257786,"size":2085,"snap":"2019-35-2019-39","text_gpt3_token_len":593,"char_repetition_ratio":0.13214801,"word_repetition_ratio":0.014814815,"special_character_ratio":0.25659472,"punctuation_ratio":0.16802168,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9859371,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-08-25T12:22:44Z\",\"WARC-Record-ID\":\"<urn:uuid:ff657cd6-5273-44c7-9854-ced8a181118f>\",\"Content-Length\":\"37672\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:7988e4e9-ff03-482b-a231-e9ff62b0ce78>\",\"WARC-Concurrent-To\":\"<urn:uuid:d11308ac-2ab7-4272-b0a5-aadc52e5f5e6>\",\"WARC-IP-Address\":\"132.236.27.47\",\"WARC-Target-URI\":\"https://projecteuclid.org/euclid.agt/1511895851\",\"WARC-Payload-Digest\":\"sha1:AWWJ4SKTNEZEQRMGCS4NUYEZOXXY4NCD\",\"WARC-Block-Digest\":\"sha1:XIUAGJMLRJFW3LTHV6UYWHYVAWCAYXHH\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-35/CC-MAIN-2019-35_segments_1566027323328.16_warc_CC-MAIN-20190825105643-20190825131643-00067.warc.gz\"}"} |
https://www.physicsforums.com/threads/this-is-so-simple-why-cant-i-figure-it-out.373801/ | [
"# This is SO simple, why can't I figure it out?\n\nThis is SO simple, why can't I figure it out??\n\nI need to figure out the length of 2 strings and L1+L2 = 4\n\nI get to the point, using other parts of the problem that are not pertinent to this, of:\n1.11L2 + L2 = 4\n\nThe answer is L2 = 1.9\n\nHOW in the world does L2 work out to be 1.9?\nHow do you solve the above equation for L2?\n\nCan someone please explain to me the algebra or some rule that I have forgotten that solves L2 as 1.9.\n\nThank you!!!!\n\nRelated Precalculus Mathematics Homework Help News on Phys.org\nMark44\nMentor\n\n1.11 L2 + L2 = 4\n==> 2.11 L2 = 4\n==> L2 = 1.8957 (approx.)\n\nHallsofIvy"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.9619172,"math_prob":0.9629829,"size":848,"snap":"2020-24-2020-29","text_gpt3_token_len":266,"char_repetition_ratio":0.116113745,"word_repetition_ratio":0.8852459,"special_character_ratio":0.32665095,"punctuation_ratio":0.14351852,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99393255,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-07-13T06:11:28Z\",\"WARC-Record-ID\":\"<urn:uuid:5bd947a5-f9cf-420c-a952-05e054fcaff1>\",\"Content-Length\":\"68758\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:b31d33d0-afb6-468d-a756-ce4d2db38cf0>\",\"WARC-Concurrent-To\":\"<urn:uuid:a7eaaede-0e5f-4afe-b943-94555542e1be>\",\"WARC-IP-Address\":\"23.111.143.85\",\"WARC-Target-URI\":\"https://www.physicsforums.com/threads/this-is-so-simple-why-cant-i-figure-it-out.373801/\",\"WARC-Payload-Digest\":\"sha1:HITUYYA5BM5ZKIMWX6OBQHTRGQ3YJ2WY\",\"WARC-Block-Digest\":\"sha1:DJGBVFPZXP4TQMU52YEF27ODD43AG2KB\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-29/CC-MAIN-2020-29_segments_1593657142589.93_warc_CC-MAIN-20200713033803-20200713063803-00010.warc.gz\"}"} |
https://www.jpost.com/israel/first-indictment-served-in-tel-aviv-pedophile-ring-case | [
"(function (a, d, o, r, i, c, u, p, w, m) { m = d.getElementsByTagName(o), a[c] = a[c] || {}, a[c].trigger = a[c].trigger || function () { (a[c].trigger.arg = a[c].trigger.arg || []).push(arguments)}, a[c].on = a[c].on || function () {(a[c].on.arg = a[c].on.arg || []).push(arguments)}, a[c].off = a[c].off || function () {(a[c].off.arg = a[c].off.arg || []).push(arguments) }, w = d.createElement(o), w.id = i, w.src = r, w.async = 1, w.setAttribute(p, u), m.parentNode.insertBefore(w, m), w = null} )(window, document, \"script\", \"https://95662602.adoric-om.com/adoric.js\", \"Adoric_Script\", \"adoric\",\"9cc40a7455aa779b8031bd738f77ccf1\", \"data-key\");\nvar domain=window.location.hostname; var params_totm = \"\"; (new URLSearchParams(window.location.search)).forEach(function(value, key) {if (key.startsWith('totm')) { params_totm = params_totm +\"&\"+key.replace('totm','')+\"=\"+value}}); var rand=Math.floor(10*Math.random()); var script=document.createElement(\"script\"); script.src=`https://stag-core.tfla.xyz/pre_onetag?pub_id=34&domain=\\${domain}&rand=\\${rand}&min_ugl=0\\${params_totm}`; document.head.append(script);"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.9491984,"math_prob":0.96919554,"size":623,"snap":"2023-40-2023-50","text_gpt3_token_len":133,"char_repetition_ratio":0.08077545,"word_repetition_ratio":0.0,"special_character_ratio":0.19903691,"punctuation_ratio":0.06140351,"nsfw_num_words":4,"has_unicode_error":false,"math_prob_llama3":0.9789482,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-10-03T12:09:06Z\",\"WARC-Record-ID\":\"<urn:uuid:00ac906d-9509-49ab-851e-2be04c5d2b4d>\",\"Content-Length\":\"78711\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:796a0d67-6300-4190-b9f2-2f473bf8bea3>\",\"WARC-Concurrent-To\":\"<urn:uuid:3d25e6be-d4da-4404-896c-59add187dd2d>\",\"WARC-IP-Address\":\"159.60.130.79\",\"WARC-Target-URI\":\"https://www.jpost.com/israel/first-indictment-served-in-tel-aviv-pedophile-ring-case\",\"WARC-Payload-Digest\":\"sha1:HSS5F3XBFZXL4AUDMHOFZQOTAVQTRG2A\",\"WARC-Block-Digest\":\"sha1:PHVQPCZL43LAVIQZOSCLX7ZJNNYRWX7R\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-40/CC-MAIN-2023-40_segments_1695233511075.63_warc_CC-MAIN-20231003092549-20231003122549-00810.warc.gz\"}"} |
https://trends.fbm.vutbr.cz/index.php/trends/article/view/135 | [
"# Estimation of the Behavioral Equilibrium Real Exchange Rate of the Czech Koruna\n\n• Vít Pošta\n\n## Keywords:\n\nBEER, equilibrium real exchange rate, productivity differential, real exchange rate, VEC\n\n## Abstract\n\nPurpose of the article: The paper examines the behavior of the real exchange rate in the Czech Republic. It focuses on the analysis of its driving forces with the emphasis on the turbulences which have been lately seen in the financial and real sector of the economy. Methodology/methods: Real equilibrium exchange rate can be estimated using various approaches ranging from purely statistical to fully structural models. In this paper it is estimated using the BEER methodology, i.e. behavioral equilibrium exchange rate. The BEER approach as applied here rests on building vector error correction models which relate the behavior of the actual real exchange rate to various economic fundamentals from both the real and financial sector of the economy. Scientific aim: The estimated behavioral equilibrium exchange rate serves as a benchmark to which the actual behavior of real exchange rate is compared. The paper also points to various problems that are faced when estimating the real equilibrium exchange rate in a posttransitive economy. Findings: Three variants of the model, which differ in the respective fundamental variables inluded in the estimation, are estimated in the paper. The gap between the estimated real equilibrium exchange rate and real exchange rate as well as the key determinants of the real equilibrium exchange rate are analyzed and compared. The models show that the misalignment between the real exchange rate and fundamentals have narrowed in the recession and post recession period. The key drivers of the real equilibrium exchange rate are the productivity differential, real interest rate differential and net foreign assets. Conclusions: (limits, implications etc) The relatively short time series for the Czech economy, especially for some of the variables, do not enable to make reliable estimation of models which would include all of the variables discussed in this paper. This paper is a part of a research project financed by IGA University of Economics, Prague"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.91623425,"math_prob":0.8866121,"size":2262,"snap":"2023-40-2023-50","text_gpt3_token_len":414,"char_repetition_ratio":0.18644819,"word_repetition_ratio":0.020710059,"special_character_ratio":0.17064545,"punctuation_ratio":0.08443272,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9700914,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-09-24T11:09:48Z\",\"WARC-Record-ID\":\"<urn:uuid:26249f8d-b8f2-49be-b563-3efdfd0e9582>\",\"Content-Length\":\"21057\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:e03c791d-b413-4f0d-bb3c-2e963ee7336a>\",\"WARC-Concurrent-To\":\"<urn:uuid:4962e8a4-a34f-4ca1-a7ba-faeeb02a6ca4>\",\"WARC-IP-Address\":\"147.229.124.25\",\"WARC-Target-URI\":\"https://trends.fbm.vutbr.cz/index.php/trends/article/view/135\",\"WARC-Payload-Digest\":\"sha1:N4VVQC3X5CZ7CBNKULVI6C7UPVBKOPVA\",\"WARC-Block-Digest\":\"sha1:C4QBA63DA3V2MHNATW6VFVFHVWEIG7OY\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-40/CC-MAIN-2023-40_segments_1695233506632.31_warc_CC-MAIN-20230924091344-20230924121344-00578.warc.gz\"}"} |
https://dba.stackexchange.com/questions/257844/sql-query-returning-same-value-while-using-where-1-condition | [
"# SQL Query returning same value while using where 1 condition\n\nI have created a temp table and inserted the values as given below.\n\n``````create table #temp( val int );\n\ninsert into #temp values(333);\ninsert into #temp values(222);\ninsert into #temp values(111);\n``````\n\nOn querying the below select statement I got 333 as the answer.\n\n``````Select *\nfrom #temp a\nWhere 1 =(\nSelect COUNT(VAL)\nfrom #temp b\nwhere a.val <= b.val\n);\n``````\n\nResult:\n\n``````val\n\n333\n``````\n\n• SQL server returned exactly what you requested. What is your expected result? Jan 21, 2020 at 10:00\n• @DenisRubashkin, Can you please explain how did query return 333? Jan 21, 2020 at 10:03\n• You ask server to find the record for which there exists only one record with the value of `val` equal or greater (so this 'only one' is this record itself) if it is alone (count=1, not duplicated). And you obtain strictly the record which matches this conditions. Why you're surprised? Jan 21, 2020 at 10:15\n\nRewrite your query such a way:\n\n``````SELECT a.*, x.cnt\nFROM #temp a\nCROSS APPLY (\nSELECT COUNT(VAL) AS cnt\nFROM #temp b\nWHERE a.val <= b.val\n) x\n--WHERE x.cnt = 1\n``````\n\nIf you uncomment the where clause you would get `333 | 1` as a result. You request a row from the outer table which doesn't have duplicates or bigger values.\n\nYou could see your inner count query\n\n``````Select COUNT(VAL) from #temp b\nwhere a.val <= b.val;\n``````\n\nas\n\n``````(Select COUNT(VAL) from #temp b\nwhere 333 <= 333,222,111) = 1\n\n(Select COUNT(VAL) from #temp b\nwhere 222 <= 333,222,111) = 2\n\n(Select COUNT(VAL) from #temp b\nwhere 111 <= 333,222,111) = 3\n``````\n\nShowing that only `333` from `#temp a` has one match, as it has only one equals to or smaller than match with the 3 values in `#temp b`.\n\nThis returns a count of `1` and is why the value `333` from `#temp a` is returned."
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.83228546,"math_prob":0.92270625,"size":624,"snap":"2022-27-2022-33","text_gpt3_token_len":154,"char_repetition_ratio":0.13387097,"word_repetition_ratio":0.0,"special_character_ratio":0.27083334,"punctuation_ratio":0.12,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.98399216,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-06-27T03:17:03Z\",\"WARC-Record-ID\":\"<urn:uuid:eb7d6079-39db-446b-8f1e-ae914ea6a3e9>\",\"Content-Length\":\"239857\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:06b5f35f-7527-4ce9-98c7-3e496f5930d6>\",\"WARC-Concurrent-To\":\"<urn:uuid:056121d6-39bd-4ef9-bada-13f0443641c7>\",\"WARC-IP-Address\":\"151.101.193.69\",\"WARC-Target-URI\":\"https://dba.stackexchange.com/questions/257844/sql-query-returning-same-value-while-using-where-1-condition\",\"WARC-Payload-Digest\":\"sha1:ZDXHXQKBMXFAOLJEI4LTLAKJZ64KOZQK\",\"WARC-Block-Digest\":\"sha1:RWXFD7RPJV7EEV56KSXEVXBLDOVK26VF\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-27/CC-MAIN-2022-27_segments_1656103324665.17_warc_CC-MAIN-20220627012807-20220627042807-00717.warc.gz\"}"} |
https://gameplay.tips/guides/1124-dishonored-death-of-the-outsider.html | [
"# Dishonored: Death of the Outsider – Bank Vault Code and Fibonacci\n\nOther Dishonored: Death of the Outsider Guides:\n\n## Fibonacci\n\n“In mathematics, the Fibonacci numbers are the numbers in the following integer sequence, called the Fibonacci sequence, and characterized by the fact that every number after the first two is the sum of the two preceding ones” – Wikipedia description of the Fibonacci numbers.\n\nThat means starting with the numbers 0, 1 and we write down the next numbers in the sequence we will be getting an infinite amount of numbers.\n\nWhat it has to do with DotO? – the chalkboard you find shows the depiction and the first numbers in the Fibonacci sequence. We get:\n\n0, 1, 1, 2, 3, 5, 8, 13\n\n## Calculation\n\nUsing the rules for the Fibonacci numbers we can calculate:\n\n• 0\n• 1\n• 1 + 1 = 2\n• 1 + 2 = 3\n• 2 + 3 = 5\n• 3 + 5 = 8\n• 5 + 8 = 13\n\n## The Vault\n\nIn the vault we have 6 safes which need – if we count the safe with key locks as a normal safe – 6 x 3 = 18 numbers. Since we only have 8 (counting any number from 10 up as 2 numbers since the pads only feature numbers from 0 – 9) which means we have to add numbers to our list.\n\nDone right following the Fibonacci numbers we would get a list with the numbers\n0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144\n\nTo open all safes we can now just pack the numbers into packets of 3 to fit into the locks:\n\n• 1 – 011\n• 2 – 235\n• 3 – 813\n• 4 – 213 This one can be skipped as it is outfitted with different locks.\n• 5 – 455\n• 6 – 891"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8608997,"math_prob":0.9965943,"size":1919,"snap":"2022-40-2023-06","text_gpt3_token_len":560,"char_repetition_ratio":0.1535248,"word_repetition_ratio":0.07235142,"special_character_ratio":0.30536738,"punctuation_ratio":0.114285715,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9934742,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-09-27T05:37:13Z\",\"WARC-Record-ID\":\"<urn:uuid:327f401d-653e-43b9-b321-80e30cee8a31>\",\"Content-Length\":\"135310\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:2f18d262-cf0d-4059-be4c-403f8974c949>\",\"WARC-Concurrent-To\":\"<urn:uuid:f28e2630-c004-4b17-98ba-a8c5a45c7776>\",\"WARC-IP-Address\":\"172.67.72.139\",\"WARC-Target-URI\":\"https://gameplay.tips/guides/1124-dishonored-death-of-the-outsider.html\",\"WARC-Payload-Digest\":\"sha1:C7BBNU24M67ATN5AGRKY56MZQPL6ETYD\",\"WARC-Block-Digest\":\"sha1:N3JC7ZZ2GPK66V43O6V4WIOZUODBSPKQ\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-40/CC-MAIN-2022-40_segments_1664030334987.39_warc_CC-MAIN-20220927033539-20220927063539-00147.warc.gz\"}"} |
http://doc.51windows.net/jscript5/html/jsobjActiveXObject.htm | [
"ActiveXObject 对象\n\n`newObj = new ActiveXObject(servername.typename[, location])`\n\nActiveXObject 对象语法有这些部分:\n\nnewObj\n\nservername\n\ntypename\n\nlocation\n\n说明\n\nAutomation 服务器至少提供一类对象。例如,字处理应用程序可能提供应用程序对象、文档对象和工具栏对象。\n\n``````var ExcelSheet;\nExcelApp = new ActiveXObject(\"Excel.Application\");\nExcelSheet = new ActiveXObject(\"Excel.Sheet\");``````\n\n````// `使` Excel `通过` Application `对象可见。\n`ExcelSheet.Application.Visible = true;`\n`// `将一些文本放置到表格的第一格中。\n`ExcelSheet.ActiveSheet.Cells(1,1).Value = \"This is column A, row 1\";`\n`// `保存表格。\n`ExcelSheet.SaveAs(\"C:\\\\TEST.XLS\");`\n`// `用` Application `对象用` Quit `方法关闭` Excel`。\n`ExcelSheet.Application.Quit();````\n\n``````function GetAppVersion() {\nvar XLApp = new ActiveXObject(\"Excel.Application\", \"MyServer\");\nreturn(XLApp.Version);\n```}```\n\n请参阅\n\nGetObject 函数\n\nwww.51windows.Net"
] | [
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] | {"ft_lang_label":"__label__zh","ft_lang_prob":0.8214831,"math_prob":0.4064026,"size":1292,"snap":"2019-26-2019-30","text_gpt3_token_len":572,"char_repetition_ratio":0.185559,"word_repetition_ratio":0.0,"special_character_ratio":0.19117647,"punctuation_ratio":0.16477273,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9638064,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-06-20T18:01:33Z\",\"WARC-Record-ID\":\"<urn:uuid:82335149-c438-4391-b9e5-2919807f8e65>\",\"Content-Length\":\"4085\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:2a3384cf-fab5-469e-81e3-3aebb4ff4821>\",\"WARC-Concurrent-To\":\"<urn:uuid:58afe6b0-df55-4541-8496-ae331dc37398>\",\"WARC-IP-Address\":\"120.92.10.42\",\"WARC-Target-URI\":\"http://doc.51windows.net/jscript5/html/jsobjActiveXObject.htm\",\"WARC-Payload-Digest\":\"sha1:MLEOC3JWMOXALV34UIW62RQ5RFZUPG4V\",\"WARC-Block-Digest\":\"sha1:ZIQLEM6MTHRHYQCP6ZDKXMBGBOAUYOHY\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-26/CC-MAIN-2019-26_segments_1560627999263.6_warc_CC-MAIN-20190620165805-20190620191805-00427.warc.gz\"}"} |
https://www.mathematicalway.com/mathematics/trigonometry/cotangent/ | [
"# Cotangent",
null,
"",
null,
"",
null,
"",
null,
"",
null,
"(No Ratings Yet)",
null,
"Loading...",
null,
"The cotangent is the reciprocal trigonometric ratio of the tangent. It is the reciprocal or multiplicative inverse of the tangent, that is, tan θ · cotθ = 1.\n\nIn a right triangle, the cotangent of the angle θ is defined as the ratio of the adjacent leg (b) to the opposite leg (a).",
null,
"Like other trig functions, it is usually abbreviated. So, in a formula, the cotangent is abbreviated as cot (cotangent-, cotangens: from co ”mutually” + Latin tangens, that means “to touch” (Latin verb: tangere)).\n\n## Cotangent for Special Common Angles\n\nThe following table gives the values of cotangent for common angles:",
null,
"",
null,
"## Properties of Cotangent\n\n• Domain:",
null,
"(all real numbers), except n · π, where n is an integer. Or this casuistry: x ≠ ±π; ±2π; ±3π;… (that is, odd multiples of π).\n• Range:",
null,
"(all real numbers)\n• Symmetry: since cot (-x) = -cot (x) then cot (x) is an odd function and its graph is symmetric with respect to the origin (0, 0).\n• Increasing-decreasing behaviour: over one period and from 0 to 2π, sec (x) is decreasing.\n• End behaviour: The limits as x approaches π+ k · π do not exist since the function values oscillate between -∞ and +∞. Hence, there are no horizontal asymptotes. This is a periodic function with period π.\n• The derivative of cotangent function:",
null,
"• The integral of cotangent function:",
null,
"## Graphical Representation of the Cotangent Function",
null,
"The cotangent is a periodic function with period π radians (180 degrees), so this section of the graph will be repeated in different periods.\n\n## Geometric Representation of the Cotangent",
null,
"## Relationship Between Cotangent and Other Trigonometric Functions\n\nThere are some basic trigonometric identities involving cotangent:\n\n• Relationship between cotangent and sine:",
null,
"• Relationship between cotangent and cosine:",
null,
"• Relationship between cotangent and tangent:",
null,
"• Relationship between cotangent and secant:",
null,
"• Relationship between cotangent and cosecant:",
null,
"(1) Note: the sign depends on the quadrant of the original angle.\n\n## Trigonometric Identities Involving the Cotangent Function\n\n### Cotangent of Complementary, Supplementary and Conjugate Angles\n\n• Cotangent of a Complementary Angle:",
null,
"• Cotangent of a Supplementary Angle:",
null,
"• Cotangent of a Conjugate Angle:",
null,
"### Cotangent of Negative Angles\n\n• Cotangent of a Negative Angle:",
null,
"### Cotangent of Angles that Differs by 90º or 180º\n\n• Cotangent of an Angle that Differs by 90º:",
null,
"• Cotangent of an Angle that Differs by 180º:",
null,
"## Other Reciprocal Trigonometric Ratios\n\nReciprocal trigonometric ratios are the multiplicative inverses of trigonometric ratios. These are:\n\n• Secant (sec): It is the reciprocal ratio of the cosine. That is, sec θ · cos θ = 1.",
null,
"• Cosecant (csc): It is the reciprocal ratio of the sine. That is, csc θ · sen θ = 1 or csc θ = 1/sen θ.",
null,
"## Reciprocal Trigonometric Ratios for Special Common Angles\n\nThe inverse trigonometric ratios for the most common angles (0º, 30º, 45º, 60º, 90º, 180º and 270º) are:",
null,
"## Relationships Between Trigonometric Functions\n\nAny trigonometric ratio can be expressed in terms of any other. The following table shows the formulas with which each one is expressed as a function of the other:",
null,
"Note: the sign + or – depends on the quadrant of the original angle.\n\n## Trigonometric Ratios of Angle θ",
null,
"If θ is one of the acute angles in a right triangle ABC, then:\n\n• The sine is the ratio between the length of the oppisite leg (a) divided by the length of the hypotenuse (c). In a formula, it is written simply as sin:",
null,
"• The cosine is the ratio between the length of the adjacent leg (b) divided by the length of the hypotenuse (c). In a formula, it is written simply as cos:",
null,
"• The tangent is the ratio between the length of the opposite leg (a) divided by the length of the adjacent leg (b). In a formula, it is written simply as tan:",
null,
"## Trigonometric Functions\n\nTrigonometric functions are also called circular functions. The reason is that in a right triangle that has been drawn on the coordinate axis, with the vertex of the angle θ at the center of a circle (O), that is, in standard position, its vertex B can go through all the points of this circle.",
null,
"Trigonometric functions and reciprocal trigonometric functions can be graphically represented in a right triangle on a circle of r=1.\n\nAUTHOR: Bernat Requena Serra\n\nYEAR: 2021"
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https://rdrr.io/github/danheck/RRreg/man/RRsimu.html | [
"# RRsimu: Monte Carlo simulation for one or two RR variables In danheck/RRreg: Correlation and Regression Analyses for Randomized Response Data\n\n RRsimu R Documentation\n\n## Monte Carlo simulation for one or two RR variables\n\n### Description\n\nSimulate and analyse bivariate data including either one RR variable (either correlation, logistic, or linear regression model) or two RR variables (only correlations). Useful for power analysis, parametric bootstraps or for testing the effects of noncompliance on the stability of estimates.\n\n### Usage\n\n```RRsimu(\nnumRep,\nn,\npi,\nmodel,\np,\ncor = 0,\nb.log = 0,\ncomplyRates = c(1, 1),\nsysBias = c(0, 0),\nmethod = c(\"RRuni\", \"RRcor\", \"RRlog\", \"RRlin\"),\nalpha = 0.05,\ngroupRatio = 0.5,\nMLest = FALSE,\ngetPower = TRUE,\nnCPU = 1\n)\n```\n\n### Arguments\n\n `numRep` number of replications `n` sample size `pi` true proportion of carriers of sensitive attribute (for 2 RR variables: `vector`) `model` either one or two RR model (as `vector`), see `RRuni` `p` randomization probability (for 2 RR variables: a `list`). See `RRuni` for details. `cor` true Pearson-correlation used for data generation (for `RRcor`). Can also be used to generate data with two dichotomous RR variables. `b.log` true regression coefficient in logistic regression (for `RRlog`) `complyRates` vector with two values giving the proportions of participants who adhere to the instructions in the subset with or without the sensitive attribute, respectively (for 2 RR variables: a `list`) `sysBias` probability of responding 'yes' (coded as 1 in the RR variable) in case of non-compliance for carriers and non-carriers, respectively. See `RRgen` `method` vector specifying which RR methods to be used in each replication. For a single RR variable, the methods `RRuni`, `RRcor`,`RRlog`, and `RRlin` are available. For 2 RR variables, only `RRcor` is available. `alpha` significance threshold for testing the logistic regression parameter `beta` `groupRatio` proportion of participants in group 1. Only for two-group models (e.g., `\"SLD\"`) (for 2 RR variables: `vector`) `MLest` concerns `RRuni`: whether to use `optim` to get ML instead of moment estimates (only relevant if pi is outside of [0,1]) `getPower` whether to compute power for `method=\"RRcor\"` (performs an additional bootstrap assuming independence) `nCPU` either the number of CPU cores or a cluster initialized via `makeCluster`.\n\n### Details\n\nFor a single RR variable:\n\nThe parameter `b.log` is the slope-coefficient for the true, latent values in a logistic regression model that is used for data generation.\n\nThe argument `cor` is used for data generation for linear models. The directly measured covariate is sampled from a normal distribution with shifted means, depending on the true state on the sensitive attribute (i.e., the true, underlying values on the RR variable). For dichotomous RR variables, this corresponds to the assumption of an ordinary t-test, where the dependent variable is normally distributed within groups with equal variance. The difference in means is chosen in a way, to obtain the point-biserial correlation defined by `cor`.\n\nFor two RR variables:\n\n`cor` has to be used. In case of two dichotomous RR variables, the true group membership of individuals is sampled from a 2x2 cross table. Within this table, probabilities are chosen in a way, to obtain the point-tetrachoric correlation defined by `cor`\n\nNote, that for the FR model with multiple response categories (e.g., from 0 to 4), the specified `cor` is not the exact target of the sampling procedure. It assumes a normal distribution for each true state, with constant differences between the groups (i.e., it assumes an interval scaled variable).\n\n### Value\n\nA list containing\n\n `parEsts` matrix containing the estimated parameters `results` matrix with mean parameters, standard errors, and number of samples to which the respective method could not be fitted `power` vector with the estimated power of the selected randomized response procedures\n\n### Examples\n\n```# Not run: Simulate data according to the Warner model\n# mcsim <- RRsimu(numRep=100, n=300, pi=.4,\n# model=\"Warner\", p=.2, cor=.3)\n# print(mcsim)\n```\n\ndanheck/RRreg documentation built on Dec. 3, 2022, 7:50 p.m."
] | [
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http://export.arxiv.org/abs/2011.11822 | [
"physics.plasm-ph\n\n# Title: Simple magnetic reconnection example\n\nAbstract: In laboratory and natural plasmas of practical interest, the spatial scale $\\Delta_d$ at which magnetic field lines lose distinguishability on the time scale set by an ideal evolution differs enormously from the scale $a$ of magnetic reconnection across the field lines. In the solar corona, plasma resistivity gives $a/\\Delta_d\\sim10^{12}$, which is the magnetic Reynold number $R_m$. The standard resolution of the paradox of disparate scales is for the current density $j$ associated with the reconnecting field $B_{rec}$ to be concentrated by the ideal evolution, so $j\\sim B_{rec}/\\mu_0\\Delta_d$, an amplification by a factor $R_m$. A second resolution is for the ideal evolution to increase the ratio of the maximum to minimum separation between pairs of arbitrarily chosen magnetic field lines, $\\Delta_{max}/\\Delta_{min}$, when calculated at various points in time. Reconnection becomes inevitable when $\\Delta_{max}/\\Delta_{min}\\sim R_m$. As demonstrated using a simple model of the solar corona, the natural rate of increase in time is linear for the current density but exponential for $\\Delta_{max}/\\Delta_{min}$. Reconnection occurs on a time scale and with a current density enhanced by only $\\ln(a/\\Delta_d)$ from the ideal evolution time and from the current density $B_{rec}/\\mu_0a$. In both resolutions of the paradox, once a sufficient region has undergone reconnection, the magnetic field loses force balance and evolves ideally on an Alfv\\'en transit time. This ideal evolution generally expands the region in which $\\Delta_{max}/\\Delta_{min}$ is large.\n Subjects: Plasma Physics (physics.plasm-ph); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR) Cite as: arXiv:2011.11822 [physics.plasm-ph] (or arXiv:2011.11822v2 [physics.plasm-ph] for this version)\n\n## Submission history\n\nFrom: Allen Boozer [view email]\n[v1] Tue, 24 Nov 2020 00:57:51 GMT (619kb,D)\n[v2] Mon, 7 Dec 2020 01:32:12 GMT (743kb,D)\n\nLink back to: arXiv, form interface, contact."
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https://www.onlinemathlearning.com/exterior-angle-triangle.html | [
"",
null,
"# Exterior Angle Theorem\n\nRelated Topics:\nMore Lessons for Geometry\nMath Worksheets\n\nExamples, solutions, Videos, worksheets, games and activities to help Geometry students learn about the Exterior Angle Theorem.\nHow to define the interior and exterior angles of a triangle?\nHow to solve problems related to the exterior angle theorem using Algebra?\n\nExterior Angles\nIf one side of a triangle is extended beyond the vertex, an exterior angle is formed. This exterior angle is supplementary with its adjacent, linear angle. Since the angle sum in a triangle is also 180 degrees, the exterior angle must have a measure equal to the sum of the remaining angles, called the remote interior angles.\n\nHow to define exterior angles and their remote interior angles and how to prove their properties.\nIntroduction to the Interior and Exterior Angles of a Triangle\nThis video will define the interior and exterior angles of a triangle and then state several theorems involving the interior and exterior angles of a triangle.\nExterior Angle Theorem\nThis video explains the exterior angle theorem of geometry. The theorem is used to work out some applications in finding angles of a triangle. The Exterior Angle Theorem\nStudents learn the exterior angle theorem, which states that the exterior angle of a triangle is equal to the sum of the measures of the remote interior angles. Students are then asked to solve problems related to the exterior angle theorem using Algebra.\n\nRotate to landscape screen format on a mobile phone or small tablet to use the Mathway widget, a free math problem solver that answers your questions with step-by-step explanations.\n\nYou can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.",
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https://www.stata.com/statalist/archive/2010-09/msg00285.html | [
"",
null,
"Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.\n\n# st: Create variable as a copy of a dynamically calculated second variable\n\n From \"Wiemann, Markus\" To Subject st: Create variable as a copy of a dynamically calculated second variable Date Thu, 9 Sep 2010 11:32:48 +0200\n\n```Hi everyone,\n\nI am not sure whether the following is possible in Stata and, if yes,\n\nI want to assign a new variable a value that is already stored in a\nsecond variable. The problem is that I need a value of a variable that\nis calculated dynamically. Let me explain it in a short example: Assume\nI have the following variables:\n\nFirstYear\nValue2000\nValue2001\nValue2002\n...\nValue2010\n\nWhat I need is something like\n. gen NewVariable = Value[String(FirstYear + 1)]\nthat would read the value out of Value2006 if FirstYear had the value\n2005. Is this possible in Stata? Would I need to write a macro for that?\n\nThanks and best regards\nMarkus\n\n*\n* For searches and help try:\n* http://www.stata.com/help.cgi?search\n* http://www.stata.com/support/statalist/faq\n* http://www.ats.ucla.edu/stat/stata/\n```"
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https://www2.mdpi.com/2073-8994/12/1/48 | [
"Previous Article in Journal\nAn Integrated MCDM Approach to Train Derailment Risk Response Strategy Selection\n\nFont Type:\nArial Georgia Verdana\nFont Size:\nAa Aa Aa\nLine Spacing:\nColumn Width:\nBackground:\nArticle\n\n# Impulsive Evolution Equations with Causal Operators\n\n1\nDepartment of Mathematics, International Islamic University, Sector H-10 Islamabad, Pakistan\n2\nDepartment of Mathematics, Texas A&M University–Kingville, Kingsville, TX 78363, USA\n3\nDepartment of Mathematics, Constantin Brancusi University, Republicii 1, 210152 Targu-Jiu, Romania\n4\nSchool of Mathematics, Statistics and Applied Mathematics, National University of Ireland, H91 TK33 Galway, Ireland\n*\nAuthor to whom correspondence should be addressed.\nSymmetry 2020, 12(1), 48; https://doi.org/10.3390/sym12010048\nReceived: 6 November 2019 / Revised: 20 December 2019 / Accepted: 20 December 2019 / Published: 25 December 2019\n\n## Abstract\n\n:\nIn this paper, we establish sufficient conditions for the existence of mild solutions for certain impulsive evolution differential equations with causal operators in separable Banach spaces. We rely on the existence of mild solutions for the strongly continuous semigroups theory, the measure of noncompactness and the Schauder fixed point theorem. We consider the impulsive integro-differential evolutions equation and impulsive reaction diffusion equations (which could include symmetric kernels) as applications to illustrate our main results.\n\n## 1. Introduction\n\nLet $R$ be the set of real numbers and let $R +$ be the set of non-negative real numbers. Let E be a real Banach space endowed with the norm $·$. We denote by $C ( [ 0 , T ] , E )$ the Banach space of continuous functions from $[ 0 , T ]$ into E endowed with the norm $u ( · ) = sup 0 ≤ t ≤ a u t$. The space of all strongly measurable functions $u ( · ) : [ 0 , T ] → E$ such that\n$u ( · ) p : = ∫ 0 T u ( t ) p 1 / p < ∞$\nfor $1 ≤ p < ∞$ and $u ( · ) ∞ : = e s s sup t ∈ [ 0 , T ] u ( t ) < ∞$, will be denoted by $L p ( [ 0 , T ] , E )$. This is a Banach space with respect to the norm $u ( · ) p$. Let $P C ( [ 0 , T ] , E )$ be the set of all functions $u ( · ) : [ 0 , T ] → E$ such that $u ( · )$ is continuous at $t ≠ t k$, left continuous at $t = t k$ and the right limit $u ( t k + )$ exists for $k = 1 , 2 , … , N$. Then $P C ( [ 0 , T ] , E )$ is a Banach space with respect to the norm $| | u ( · ) | | P C : = sup { | | u ( t ) | | ; t ∈ [ 0 , T ] }$. Moreover, we have that $P C ( [ 0 , T ] , E ) ⊂ L p ( [ 0 , T ] , E )$ and\n$u · 1 ≤ T 1 − 1 / p u · p ≤ T 2 − 1 / p u · P C .$\nLet us denote by $F 1 ( [ 0 , T ] , X )$ the space of all the functions from $[ 0 , T ]$ into X, and by $F 2 ( [ 0 , T ] , Y )$ the space of all the functions from $[ 0 , T ]$ into Y. Then an operator $C : F 1 ( [ 0 , T ] , X ) → F 2 ( [ 0 , T ] , Y )$ is called a causal operator if for each $τ ∈ ( 0 , T )$ and for all $u · , v · ∈ F 1 ( [ 0 , T ] , X )$ such that $u t = v t$ for $t ∈ [ 0 , τ ]$, we have that $C u ( t ) = C v ( t )$ for $t ∈ [ 0 , τ ]$, and $C 0 ( t ) = 0$ for all $t ∈ [ 0 , T ]$.\nThe aim of this paper is to establish existence results for mild solutions of the following impulsive evolution equation with the causal operator\n$u ′ ( t ) = A u ( t ) + ( C u ) ( t ) for t ∈ [ 0 , T ] \\ { t 1 , … t N } u ( t k + ) = u ( t k − ) + ( I k u ) ( t k − ) u ( 0 ) = u 0 ,$\nwhere $A : D ( A ) ⊂ E → E$ is the infinitesimal generator of a $C 0$-semigroup ${ T ( t ) ; t ≥ 0 }$ and $C : P C ( [ 0 , T ] , E ) → L p ( [ 0 , T ] , E )$ is a continuous causal operator; here $1 ≤ p ≤ ∞$, $N ∈ N$, $0 = t 0 < t 1 < t 2 < … < t N < t N + 1 = T$ and $I k : P C ( [ 0 , T ] , E ) → P C ( [ 0 , T ] , E )$ is a continuous causal operator for each $k = 1 , 2 , … , N$.\nThe theory of differential equations involving causal operators allows a unified treatment for general classes of differential equations, such as: Ordinary differential equations, differential equations with delay, integro-differential equations, Volterra integral equations and so on. The term causal operator (or Volterra abstract operator) was introduced by Tonelli , and the theory of these classes of operators was developed by Tychonoff . The class of causal operators is quite large and it includes a number of operators that are used in mathematical modeling of some phenomena in engineering and physics. An important class of causal operators is the class of superposition operators or Nemytskij operators (see ) $C : L p ( [ 0 , T ] , E ) → L p ( [ 0 , T ] , E )$ defined by $( C u ) ( t ) : = F ( t , u ( t ) )$, where $F : [ 0 , T ] × E → E$ is a Caratheodory function. If $σ > 0$, then $C : C ( [ − σ , T ] , E ) → L p ( [ 0 , T ] , E )$ defined by $( C u ) ( t ) : = F ( t , u ( t ) , u ( t − σ ) )$ is another example of a causal operator. A more general example of causal operators is the operator $C : C ( [ − σ , T ] , E ) → L p ( [ 0 , T ] , E )$ defined by\n$( C u ) ( t ) : = F t , u ( t ) , u ( t − σ ) , ∫ t − σ t K ( t , s , u ( s ) ) d s .$\nSeveral examples of causal operators and their applications can be found in the monograph . Although it does not specifically study the theory of causal operators, several monographs, such as [5,6,7,8,9], address some aspects of differential equations involving causal operators. Detailed studies on differential equations with causal operators in finite dimensional spaces can be found in the monographs [4,10,11,12]. Applications of differential equations with causal operators in optimal control, adaptive control or hysteresis phenomena can be found in the papers [13,14,15,16,17,18,19,20]. Theoretical aspects regarding existence, stability or periodicity of solutions of differential equations with causal operators in finite or infinite dimensional spaces were presented in a series of works, such as: [21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39].\nThe study of evolution equations with causal operators was first presented in , where an existence result was obtained and some applications were given, but impulsive evolution differential equations with causal operators has not yet been studied. In this paper we study the class of impulsive evolution equations involving causal operators. In Section 2 we recall some results on $C 0$-semigroups of linear operators and some properties of the Hausdorff measure of noncompactness. In Section 3 we obtain the existence of mild solutions for a class of impulsive evolution equations with causal operators. Also, we show that a mild solution can be obtained as the limit of a sequence of successive approximations. In the last section we give some applications.\n\n## 2. Preliminaries\n\nWe denote the space of all bounded linear operators acting on a Banach space E by $L ( E )$. We recall that a family $T ( t ) ; t ≥ 0 ⊂ L ( E )$ is called a $C 0$-semigroup if the following three properties are satisfied:\n(a)\n$T ( 0 ) = I ,$ the identity operator on E;\n(b)\n$T ( t ) T ( s ) = T ( t + s )$ for all $t , s ≥ 0$;\n(c)\n$lim t → 0 + T ( t ) u = u$ for all $u ∈ E$.\nThe infinitesimal generator of the $C 0$-semigroup ${ T ( t ) ; t ≥ 0 }$ is the operator $A : D ( A ) ⊂ E → E$, defined by\n$D ( A ) = { u ∈ E ; lim h → 0 + T ( h ) u − u h exists }$\nand\n$A u = lim h → 0 + T ( h ) u − u h , u ∈ D ( A ) .$\nThe generator is always a closed, densely defined operator. For further details on the theory of the $C 0$-semigroups see [41,42].\nWe denote by $χ ( B )$ the Hausdorff measure of non-compactness of a nonempty bounded set $B ⊂ E$, and it is defined by :\nWe recall some properties of $χ$ (see ). If $A , B$ are bounded subsets of E, then\n($χ$1)\n$χ ( B ) = 0$ if and only if $B ¯$ is compact;\n($χ$2)\n$χ ( B ) = χ ( B ¯ ) = χ ( c o n v ¯ ( B ) )$;\n($χ$3)\n$χ ( λ B ) = | λ | χ ( B )$ for every $λ ∈ R$;\n($χ$4)\n$χ ( B ) ≤ χ ( C )$ if $B ⊂ C$;\n($χ$5)\n$χ ( { x } ∪ B ) = χ ( B )$ for every $x ∈ E$;\n($χ$6)\n$χ ( B + C ) = χ ( B ) + χ ( C )$.\n($χ$7)\nGeneralized Cantor’s intersection property : If $B n n ≥ 1$ is a decreasing sequence of bounded closed nonempty subsets of E and $lim n → ∞ χ ( B n ) = 0$, then $⋂ n = 1 ∞ B n$ is a nonempty and compact subset of E (see ).\nRemark 1.\nIf $d i a m ( B ) = sup { | | x − y | | ; x , y ∈ B }$ is the diameter of the bounded set A, then we have that $χ ( B ) ≤ d i a m ( B )$ and $χ ( B ) ≤ 2 d$ if $sup x ∈ B | | x | | ≤ d$.\nIn the following, we denote by $χ c$ the Hausdorff measure of non-compactness in the space $C ( [ 0 , T ] , E )$. Then it is well known that for every bounded set $B ⊂ C ( [ 0 , T ] , E )$ we have\n$χ ( B ( t ) ) ≤ χ c ( B ) ,$\nfor every $t ∈ [ 0 , T ]$, where $B ( t ) : = { u ( t ) : u ∈ B }$. Moreover, for every bounded and equicontinuous set $B ⊂ C ( [ 0 , T ] , E )$ we have (see )\n$χ c ( B ) = sup 0 ≤ t ≤ T χ ( B ( t ) ) .$\nFor each $k = 0 , 1 , 2 , … , N$ and $u ( · ) ∈ P C ( [ 0 , T ] , E )$ we set $J k = ( t k , t k + 1 ]$ , $J ¯ k = [ t k , t k + 1 ]$ and introduce the function $u ˜ k ( · ) ∈ C ( J ¯ k , E )$ defined by\n$u ˜ k ( t ) = u ( t ) , for t ∈ J k u ( t k + ) , for t = t k .$\nAlso, for $B ⊂ P C ( [ 0 , T ] , E )$ and $k = 0 , 1 , 2 , … , N$, let us set $B ˜ k : = { u ˜ k ( · ) ∈ C ( J ¯ k , E ) ; u ( · ) ∈ B }$.\nIf we denote by $χ k$ the Hausdorff measure of noncompactness on $C ( J ¯ k , E )$, then\n$χ P C ( B ) : = max 0 ≤ k ≤ N χ k B ˜ k , B ⊂ P C ( [ 0 , T ] , E )$\ndefines the Hausdorff measure of noncompactness on $P C ( [ 0 , T ] , E )$. Moreover, it is easy to see that\n$χ P C ( B ) = sup t ∈ [ 0 , T ] χ B t$\nfor every equicontinuous subset $B ⊂ P C ( [ 0 , T ] , E )$.\nLemma 1\n(, Lemma 2.1). A set $B ⊂ P C ( [ 0 , T ] , E )$ is relatively compact in $P C ( [ 0 , T ] , E )$ if and only if $B ˜ k$ is relatively compact in $C ( J ¯ k , E )$ for every $k = 0 , 1 , 2 , … , N$.\nLemma 2\n(, p. 125). If $B ⊂ E$ is a nonempty bounded set, then for every $ε > 0$ there exists a sequence ${ x n } n ≥ 1$ in E such that\n$χ ( B ) ≤ 2 χ { x n ; n ≥ 1 } + ε .$\nLemma 3\n(, Lemma 2.2). Let ${ u n ( · ) ; n ≥ 1 }$ be a subset in $L 1 ( [ 0 , T ] , E )$ for which there exists $m ( · ) ∈ L 1 ( [ 0 , T ] , R + )$ such that $u n ( t ) ≤ m ( t )$ for each $n ≥ 1$ and for a.e. $t ∈ [ 0 , T ]$. Then the function $t ↦ χ ( t ) : = χ ( { u n ( t ) ; n ≥ 1 } )$ is integrable on $[ 0 , T ]$ and, for each $t ∈ [ 0 , T ]$, we have\n$χ ∫ 0 t u n ( s ) d s ; n ≥ 1 ≤ ∫ 0 t χ ( s ) d s .$\n\n## 3. Existence Result\n\nConsider the following impulsive differential equation\n$u ′ ( t ) = A u ( t ) + ( C u ) ( t ) for t ∈ [ 0 , T ] \\ { t 1 , … , t N } u ( t k + ) = u ( t k − ) + ( I k u ) ( t k − ) u ( 0 ) = u 0 ,$\nwhere $A : D ( A ) ⊂ E → E$ is the infinitesimal generator of a $C 0$-semigroup ${ T ( t ) ; t ≥ 0 }$ and $C : P C ( [ 0 , T ] , E ) → L p ( [ 0 , T ] , E )$ is a continuous causal operator; here $1 ≤ p ≤ ∞$, $N ∈ N$, $0 = t 0 < t 1 < t 2 < … < t N < t N + 1 = T$ and $I k : P C ( [ 0 , T ] , E ) → P C ( [ 0 , T ] , E )$ is a continuous causal operator for each $k = 1 , 2 , … , N$.\nA function $u ( · ) ∈ P C ( [ 0 , T ] , E )$ is called a mild solution of (4) if it satisfies\n$u ( t ) = T ( t ) u ( 0 ) + ∫ 0 t T ( t − s ) ( C u ) ( s ) d s + ∑ 0 < t k < t T ( t − t k ) I k ( u ( t k ) , t ∈ [ 0 , T ] .$\nLet us introduce the following conditions.\n(H1) For each $k = 1 , 2 , … , N$, $I k : P C ( [ 0 , T ] , E ) → P C ( [ 0 , T ] , E )$ is continuous and a compact operator and there exists $c k > 0$, with $M ∑ 0 < t k < T c k < 1$, such that for each $u ( · ) ∈ P C ( [ 0 , T ] , E )$ we have\n$( I k u ) ( t ) ≤ c k | | u ( t ) | | for every t ∈ [ 0 , T ] ,$\nwhere $M : = sup 0 ≤ t ≤ T T ( t )$.\n(H2) (a) There exists a function $ξ ( · , · ) : [ 0 , T ] × R + → R +$ such that $ξ ( · , η ) ∈ L 1 ( [ 0 , T ] , R + )$ for every $η ∈ R +$, $ξ ( t , · )$ is continuous and increasing on $R +$ for a.e. $t ∈ [ 0 , T ]$ such that\n$lim sup η → ∞ M η u 0 + ∫ 0 T ξ ( s , η ) d s < 1 − M ∑ 0 < t k < T c k$\nand\n$C u t ≤ ξ ( t , | | u ( t ) | | ) , for a . e . t ∈ [ 0 , T ] ,$\nfor each $u ( · ) ∈ P C ( [ 0 , T ] , E )$.\n(b) For each bounded subsets $B ⊂ P C ( [ 0 ,$T$] , E )$ there exists $γ B ( · ) ∈ L 1 ( [ 0 , T ] , R + )$ such that\n$∫ 0 T γ B ( t ) d t < 1 2 M T$\nand\n$χ ( ( C B ) ( t ) ) ≤ ∫ 0 t γ B ( s ) χ ( B ( s ) ) d s for t ∈ [ 0 , T ] ,$\nwhere $( C B ) ( t ) : = { ( C u ) ( t ) : u ( · ) ∈ B }$.\nTheorem 1.\nLet $C : P C ( [ 0 , T ] , E ) → L p ( [ 0 , T ] , E )$ be a continuous causal operator such that conditions (H1) and (H2) hold. If $A : D ( A ) ⊂ E → E$ is the generator of a $C 0$-semigroup ${ T ( t ) ; t ≥ 0 }$, then the evolution Equation (4) has at least one mild solution on $[ 0 , T ] .$\nProof.\nFirst, we remark that there exists an $r > 0$ such that\n$M u 0 + M ∫ 0 T ξ ( s , r ) d s + M r ∑ 0 < t k < T c k < r .$\nIndeed, from (5) it follows that there exists $η 0 > 0$ such that\n$M η u 0 + ∫ 0 T ξ ( s , η ) d s < 1 − M ∑ 0 < t k < T c k ,$\nfor every $η > η 0$, so that\n$M u 0 + M ∫ 0 T ξ ( s , η ) d s + M η ∑ 0 < t k < T c k < η ,$\nfor every $η > η 0$. Consequently, we can choose a $r > η 0$ such that (9) holds. Now, let\n$B 0 = { u ( · ) ∈ P C ( [ 0 , T ] , E ) ; u ( · ) P C ≤ r } ,$\nand define the operator $F : B 0 → P C ( [ 0 , T ] ) , E$ by\n$( F u ) ( t ) : = T ( t ) u 0 + ∫ 0 t T ( t − s ) ( C u ) ( s ) d s + ∑ 0 < t k < t T ( t − t k ) ( I k u ) ( t k ) ,$\nfor $t ∈ [ 0 , T ]$. Since $ξ ( t , · )$ is increasing on $R +$ for a.e. $t ∈ [ 0 , T ]$ for every $u ( · ) ∈ B 0$, using (5) we have\n$( F u ) ( t ) ≤ T ( t ) u 0 + ∫ 0 t T ( t − s ) ( C u ) ( s ) d s + ∑ 0 < t k < t T ( t − t k ) ( I k u ) ( t k ) ≤ M u 0 + M ∫ 0 t ( C u ) ( s ) d s + M ∑ 0 < t k < t c k | | u ( t k ) | | ≤ M u 0 + M ∫ 0 t ξ ( s , u ( s ) ) d s + M ∑ 0 < t k < t c k | | u ( t k ) | | ≤ M u 0 + M ∫ 0 T ξ ( s , u ( s ) ) d s + M ∑ 0 < t k < T c k | | u ( t k ) | | ≤ M u 0 + M ∫ 0 T ξ ( s , r ) d s + M r ∑ 0 < t k < T c k < r ,$\nso that $F ( B 0 ) ⊂ B 0$. We notice that $C u t ≤ ψ ( t )$ for a.e. on $[ 0 , T ]$, for every $u ( · ) ∈ B 0$, where $ψ ( · ) : = ξ ( · , r ) ∈ L 1 ( [ 0 , T ] , R + )$. Let $B 1 : = F B 0$. Next, we will show that $B ˜ 1 k$ is equicontinuous on $J ¯ k$ for every $k = 1 , 2 , … , N$. For this, we shall write the operator $F$ as $F u ( t ) = F 1 u ( t ) + F 2 u ( t )$, where\n$F 1 u ( t ) = T ( t ) u 0 + ∫ 0 t T ( t − τ ) ( C u ) ( τ ) d τ ,$\n$F 2 u ( t ) = ∑ 0 < t k < t T ( t − t k ) ( I k u ) ( t k )$\nfor $t ∈ [ 0 , T ]$.\nFirst, we show that $G 1 : = F 1 B 0$ is equicontinuous on $[ 0 , T ]$. Let $ε > 0$. Since $t ↦ T ( t ) u 0$ continuous on $[ 0 , T ]$ (see , Corollary 2.3), then there exists $δ 1 = δ 1 ( ε / 5 ) > 0$ such that\n$∥ T ( t + h ) u 0 − T ( t ) u 0 ∥ ≤ ε 5$\nfor every $t ∈ [ 0 , T ]$ and $h ∈ R$ with $| h | < δ 1$ and $t + h ∈ [ 0 , T ]$. On $[ 0 , T ]$, the function $t ↦ ∫ 0 t ψ ( s ) d s$ is uniformly continuous and thus there exists $δ 2 = δ 2 ( ε / 5 M ) > 0$ such that\n$∫ t t + h ψ ( τ ) d τ < ε 5 M$\nfor every $t ∈ [ 0 , T ]$ and $h ∈ R$ with $| h | < δ 2$ and $t + h ∈ [ 0 , T ]$. Then for $t = 0$ we have\n$∥ ( F 1 u ) ( h ) − ( F 1 u ) ( 0 ) ∥ = T ( h ) u 0 + ∫ 0 h [ T ( h − τ ) ( C u ) ( τ ) d τ − u 0 ≤ ∥ T ( h ) u 0 − u 0 ∥ + ∫ 0 h T ( h − τ ) ( C u ) ( τ ) d τ ≤ ∥ T ( h ) u 0 − u 0 ∥ + M ∫ 0 h ← ( τ ) d τ < 2 ε 5 < ε ,$\nfor each $u ∈ B 0$ and $h ∈ ( 0 , T ]$ with $h < min { δ 1 , δ 2 }$. It follows that $G 1$ is equicontinuous at $t = 0$. Next, take $t ∈ ( 0 , T ]$ and let us choose $0 < η < δ 2 / 2$ such that $t − η ∈ [ 0 , T ]$. For each $u ∈ B 0$ and $h ∈ R$ such that $t + h ∈ [ 0 , T ]$ we have\n$∥ ( F 1 u ) ( t + h ) − ( F 1 u ) ( t ) ∥ ≤ ( F 1 u ) ( t ) − T ( η ) [ ( F 1 u ) ( t − η ) ] + T ( η ) [ ( F 1 u ) ( t − η ) ] − T ( η + h ) [ ( F 1 u ) ( t − η ) ] + T ( η + h ) [ ( F 1 u ) ( t − η ) ] − ( F 1 u ) ( t + h ) .$\nSince\n$( F 1 u ) ( t ) − T ( η ) [ ( F 1 u ) ( t − η ) ] = T ( t ) u 0 + ∫ 0 t T ( t − τ ) ( C u ) ( τ ) d τ − T ( η ) T ( t − η ) u 0 + ∫ 0 t − η [ T ( t − η − τ ) ( C u ) ( τ ) d τ = ∫ 0 t T ( t − τ ) ( C u ) ( τ ) d τ − ∫ 0 t − η T ( t − τ ) ( C u ) ( τ ) d τ = ∫ t − η t T ( t − τ ) ( C u ) ( τ ) d τ ≤ M ∫ t − η t ψ ( τ ) d τ ,$\nit follows that\n$( F 1 u ) ( t ) − T ( η ) [ ( F 1 u ) ( t − η ) ] ≤ M ∫ t − η t ψ ( τ ) d τ < ε 5$\nfor each $u ∈ B 0$. By similar reasoning, we obtain\n$T ( η + h ) [ ( F 1 u ) ( t − η ) ] − ( F 1 u ) ( t + h ) ≤ M ∫ t − η t + h ψ ( τ ) d τ ,$\nand so, by (13), we conclude that\n$T ( η + h ) [ ( F 1 u ) ( t − η ) ] − ( F 1 u ) ( t + h ) ≤ M ∫ t − η t + h ψ ( τ ) d τ < ε 5$\nfor each $u ∈ B 0$ and $h ∈ R$ with $| h | < η$ and $t + h ∈ [ 0 , T ]$. Furthermore, we have\n$T ( η ) [ ( F 1 u ) ( t − η ) ] − T ( η + h ) [ ( F 1 u ) ( t − η ) ] ≤ ∥ T ( t + h ) u 0 − T ( t ) u 0 ∥ + ∫ 0 t − η T ( t + h − τ ) − T ( t − τ ) ψ ( τ ) d τ ≤ ∥ T ( t + h ) u 0 − T ( t ) u 0 ∥ + 2 M ∫ 0 t − η ψ ( τ ) d τ ≤ 3 ε 5 ,$\nthat is,\n$T ( η ) [ ( F 1 u ) ( t − η ) ] − T ( η + h ) [ ( F 1 u ) ( t − η ) ] ≤ 2 ε 5$\nfor each $u ∈ B 0$ and $h ∈ R$ with $| h | < min { η , δ 1 , δ 2 }$ and $t + h ∈ [ 0 , T ]$. Now, using (15), (16) and (18), from (14) it follows that\n$∥ ( F 1 u ) ( t + h ) − ( F 1 u ) ( t ) ∥ < ε$\nfor each $u ∈ B 0$ and $h ∈ R$ with $| h | < min { η , δ 1 , δ 2 }$ and $t + h ∈ [ 0 , T ]$. Thus $G 1$ is equicontinuous on $[ 0 , T ]$. From this it follows that $G ˜ 1 k$ is equicontinuous on $J ¯ k$ for every $k = 1 , 2 , … , N$. Next, we show that, for a given $ν ∈ { 1 , 2 , … , N }$, the set $G ˜ 2 ν$ is equicontinuous on $J ¯ ν$, where $G 2 : = F 2 B 0$. Since $I k$ is a compact operator, $I k B 0$ is a relatively compact set in $P C ( [ 0 , T ] , E )$ and so, by Lemma 1 $I k B ˜ 0$ is a relatively compact set in $C ( J ¯ k , E )$ for each $k = 1 , 2 , … , N$. Using the Ascoli–Arzela theorem, from the compactness of $I k B ˜ 0$ in $C ( J ¯ k , E )$, it follows that $( I k B ˜ 0 ) ( t )$ is relatively compact in E for every $t ∈ J ¯ k$ and $k = 1 , 2 , … , N$. In particular, $( I k B ˜ 0 ) ( t k )$ is relatively compact for every $k = 1 , 2 , … , N$, and thus $K : = ⋃ k = 1 N ( I k B ˜ 0 ) ( t k )$ is relatively compact in E. Since $t , x ↦ T ( t ) x$ is jointly continuous from $[ 0 , ∞ ) × K$ to E, it follows that there exists a $δ > 0$ such that\n$T ( t − t k ) x − T ( s − t k ) x < ε / N , x ∈ K$\nfor every $t k$, $k = 1 , 2 , … , N$, $t , s ∈ J ¯ k$ with $t − s < δ$. Next, for every $u ( · ) ∈ B 0$, $t , s ∈ J ¯ ν$ with $t − s < δ$, we have\n$∥ ( F 2 u ˜ ν ) ( t ) − ( F 2 u ˜ ν ) ( s ) ∥ = ∥ ( F 2 u ) ( t ) − ( F 2 u ) ( s ) ∥ = ∑ 0 < t k < t T ( t − t k ) ( I k u ) ( t k ) − ∑ 0 < t k < t T ( s − t k ) ( I k u ) ( t k ) ≤ ∑ k = 1 ν T ( t − t k ) ( I k u ) ( t k ) − T ( s − t k ) ( I k u ) ( t k ) < ε ,$\nso that $G ˜ 2 ν$ is equicontinuous on $J ¯ ν$. Since $B ˜ 1 k = G ˜ 1 k + G ˜ 2 k$, $k = 1 , 2 , … , N$, it follows that $B ˜ 1 k$ is equicontinuous on $J ¯ k$ for every $k = 1 , 2 , … , N$. Next, for each $n ≥ 1$, we define $B n = c o n v ¯ ( F B n − 1 )$. Then, for every $n ≥ 1$, $B n ⊂ P C ( [ 0 , T ] , E )$ is a bounded, closed and convex set. Now, from $F B 0 ⊂ B 0$, it follows that\n$B 1 = c o n v ¯ ( F B 0 ) ⊂ c o n v ¯ ( B 0 ) = B 0 .$\nIf we suppose that $B ν ⊂ B ν − 1$ for a given $ν > 1$, then\n$B ν + 1 = c o n v ¯ ( F B ν ) ⊂ c o n v ¯ ( F B ν − 1 ) = B ν$\nand thus, by induction it follows that $B n ⊂ B n − 1$ for every $n ≥ 1$. Moreover, it is easy to see that $B ˜ n k$ is equicontinuous on $J ¯ k$ for each $k = 1 , 2 , … , N$ and for every $n ≥ 1$. Now, we will show that $χ P C ( B n ) → 0$ as $n → ∞$. From Lemma 2, it follows that there exists a sequence ${ v m ( · ) } m ≥ 1$ in $F B n − 1$ such that\n$χ P C ( B n ) = χ P C ( F B n − 1 ) ≤ 2 χ P C ( V ) + ε ,$\nwhere $V : = { v m ( · ) ; m ≥ 1 }$. From the above inequality it follows that\n$χ P C ( B n ) ≤ 2 max 0 ≤ k ≤ N χ k ( V ¯ n k ) + ε .$\nSince for each $k = 1 , 2 , … , N$, the equicontinuity of $V ¯ n k$ and Lemma 3 imply $χ k ( V ¯ n k ) = sup t ∈ J k χ ( V ( t ) )$, we obtain\n$χ P C ( B n ) ≤ 2 max 0 ≤ k ≤ N sup t ∈ J k χ ( V ( t ) ) + ε ≤ 2 sup t ∈ [ 0 , T ] χ ( V ( t ) ) + ε = 2 sup t ∈ [ 0 , T ] χ ( { v m ( t ) ; m ≥ 1 } ) + ε .$\nFurther, let ${ u m ( · ) } m ≥ 1$ be a sequence in $B n − 1$ such that $v m ( · ) = ( F u m ) ( · )$, $m ≥ 1$. If we put $V : = { u m ( · ) ; m ≥ 1 }$ and $V ( t ) : = { u m ( t ) ; m ≥ 1 }$, $t ∈ [ 0 , T ]$, then from the previous inequality it follows that\n$χ P C ( B n ) ≤ ε + 2 χ T ( t − s ) u 0 + ∫ 0 t T ( t − s ) ( C V ) ( s ) d s$\n$+ ∑ 0 < t k < t − T / n T ( t − t k ) ( I k V ) ( t k )$\n$≤ ε + 2 χ ∫ 0 t T ( t − s ) ( C V ) ( s ) d s$\n$+ 2 χ ∑ 0 < t k < t T ( t − t k ) ( I k V ) ( t k ) .$\nLet $t ∈ [ 0 , T ]$ be fixed. Since\n$T ( t − s ) C u m ( s ) ≤ M ψ ( t ) for a . e . s ∈ [ 0 , t ] ,$\nfor all $m ≥ 1$, and\n$χ ( { C u m ( s ) ; m ≥ 1 } ) ≤ ∫ 0 s γ V ( τ ) χ ( { u m ( τ ) ; m ≥ 1 } ) d τ ≤ ∫ 0 s γ V ( τ ) χ ( B n − 1 ( τ ) ) d τ ≤ χ P C ( B n − 1 ) ∫ 0 s γ V ( τ ) d τ$\nfor a.e. $s ∈ [ 0 , t ]$, by Lemma 3 it follows that\n$χ ∫ 0 t T ( t − s ) ( C V ) ( s ) d s ≤ ∫ 0 t χ T ( t − s ) ( C V ) ( s ) d s ≤ 2 M ∫ 0 t χ ( C V ) ( s ) d s ≤ 2 M ∫ 0 t ∫ 0 s γ V ( τ ) χ ( V ( τ ) d τ d s ≤ 2 M χ P C ( B n − 1 ) ∫ 0 t ∫ 0 s γ V ( τ ) d τ d s = 2 M χ P C ( B n − 1 ) ∫ 0 t ∫ τ t γ V ( τ ) d s d τ = 2 M χ P C ( B n − 1 ) ∫ 0 t ( t − τ ) γ V ( τ ) d τ ≤ 2 M T χ P C ( B n − 1 ) ∫ 0 T γ V ( τ ) d τ .$\nAlso, by the continuity of the operators $T ( t )$ and by the compactness of the operators $I k$, it follows that the set $T ( t − t k ) ( I k V ) ( t k )$ is relatively compact for every $t ∈ [ 0 , T ]$. Therefore, we have that\n$χ ∑ 0 < t k < t T ( t − t k ) ( I k V ) ( t k ) ≤ ∑ 0 < t k < t χ T ( t − t k ) ( I k V ) ( t k ) = 0 .$\nFrom (19), (21), and (22), we obtain\n$χ P C ( B n ) ≤ ε + ρ χ P C B n − 1 ,$\nwhere\n$ρ : = 2 M T ∫ 0 T γ V ( s ) d s < 1 .$\nSince $ε > 0$ is arbitrary, it follows that\n$χ P C ( B n ) ≤ ρ χ P C B n − 1 .$\nAlso\n$χ P C ( B n ) ≤ ρ n − 1 χ P C B 1 .$\nSince the last inequality is true for every $n ≥ 1$ and $0 < ρ < 1$, passing to the limit as $n → ∞$, we obtain $lim n → ∞ χ P C ( B n ) = 0$. Now, using the generalized Cantor’s intersection property, it follows that the set $B : = ⋂ n = 1 ∞ B n$ is a nonempty and compact subset of $P C ( [ 0 , T ] , E )$. Since every set $B n$ is a convex set, the set B is also a convex set. Next, we verify that $F B ⊂ B$. Indeed, for every $n ≥ 1$, we have that $F B ⊂ F B n ⊂ c o n v ¯ B n = B n + 1$, so that $F B ⊂ ⋂ n = 2 ∞ B n$. Also, since $B n ⊂ B 1$ for every $n ≥ 1$, it follows that $F B ⊂ ⋂ n = 2 ∞ B n ⊂ ⋂ n = 1 ∞ B n ⊂ B$. Now, we show that $F$ is a continuous operator from B into itself. For this, let $u n ( · ) → u ( · )$ in B. If $1 ≤ p < ∞$ and $1 / p + 1 / q = 1 ,$ then by Hölder’s inequality we have\n$∥ ( F u n ) ( t ) − ( F u ) ( t ) ∥ ≤ ∫ 0 t [ T ( t − s ) [ ( C u n ) ( s ) − ( C u ) ( s ) ] d s + ∑ 0 < t k < t | | T ( t − t k ) ( I k u n ) ( t k ) − ( I k u ) ( t k ) | | ] ≤ ∫ 0 t ∥ T ( t − s ) ∥ L ( E ) ∥ ( C u n ) ( s ) − ( C u ) ( s ) ∥ d s + ∑ 0 < t k < t T ( t − t k ) L ( E ) | | ( I k u n ) ( t k ) − ( I k u ) ( t k ) | | ] ≤ M ∫ 0 T ∥ ( C u n ) ( s ) − ( C u ) ( s ) ∥ d s + M ∑ 0 < t k < T | | ( I k u n ) ( t k ) − ( I k u ) ( t k ) | | ≤ M T 1 / q ∫ 0 T ∥ ( C u n ) ( s ) − ( C u ) ( s ) ∥ p d s 1 / p + M ∑ 0 < t k < T | | ( I k u n ) ( t k ) − ( I k u ) ( t k ) | | ,$\nand for $p = ∞$ we have\n$∥ ( F u m ) ( t ) − ( F u ) ( t ) ∥ ≤ ∫ 0 t ∥ T ( t − s ) ∥ ∥ ( C u n ) ( s ) − ( C u ) ( s ) ∥ d s + ∑ 0 < t k < T T ( t − t k ) | | ( I k u n ) ( t k − ) − ( I k u ) ( t k − ) | | ≤ M T · e s s sup 0 ≤ t ≤ T ∥ ( C u n ) ( t ) − ( C u ) ( t ) ∥ + M ∑ 0 < t k < T | | ( I k u n ) ( t k − ) − ( I k u ) ( t k − ) | | .$\nUsing the continuity of the operators $C$ and $I k$ it follows that for $1 ≤ p ≤ ∞$ we have that $∥ ( F u n ) ( · ) − ( F u ) ( · ) ∥ P C → 0$ as $n → ∞$, so that $F : B → B$ is a continuous operator. Since B is a nonempty compact convex set, and $F : B → B$ is a continuous operator, by Schauder’s fixed point theorem it follows that there exists at least one $u ( · ) ∈ B$ such that\n$u ( t ) = ( F u ) ( t ) = T ( t ) u 0 + ∫ 0 t T ( t − s ) ( C u ) ( s ) d s + ∑ 0 < t k < t T ( t − t k ) I k u ( t k )$\nfor all $t ∈ [ 0 , T ]$; that is, $u ( · ) ∈ B$ is a mild solution for (4). □\nRemark 2.\nIt is easy to see that the conclusion Theorem 1 remains true if (6) is replaced by\n$C u t ≤ ξ ( t , | | u ( · ) | | P C ) , f o r a . e . t ∈ [ 0 , T ] ,$\nand for each $u ( · ) ∈ P C ( [ 0 , T ] , E )$. The conclusion of Theorem 1 remains true if (H2)(b) is replaced by:\n(H2) (b′) For each bounded subset $B ⊂ P C ( [ 0 , T ] , E )$ there exists $γ B ( · ) ∈ L 1 ( [ 0 , T ] , R + )$ such that (7) holds and\n$χ ( T ( t ) ( C B ) ( t ) ) ≤ ∫ 0 t γ B ( s ) χ ( B ( s ) ) d s f o r t ∈ [ 0 , T ] .$\nIf ${ T ( t ) , t ≥ 0 }$ is a compact $C 0$-semigroup or $C$ is a compact operator, then $χ ( T ( t ) ( C B ) ( t ) ) = 0$ for $t ∈ [ 0 , T ]$ and for each bounded set $B ⊂ P C ( [ 0 , T ] , E )$ (see , Remark 8.2.1). Also, with a slight modification of the proof, the conclusion of Theorem 1 remains true if the condition (H2)(b) is replaced by:\n(H2) (b″) For each bounded subset $B ⊂ P C ( [ 0 , T ] , E )$ there exists $γ B ( · ) ∈ L 1 ( [ 0 , T ] , R + )$ such that (7) holds and\n$χ ( ( C B ) ( t ) ) ≤ γ B ( t ) χ ( B ( t ) ) f o r a . e . t ∈ [ 0 , T ] .$\nNext, suppose that $f ( · , · ) : [ 0 , T ] × E → E$ is a function which satisfies the following condition:\n(Hf) (a) $f : [ 0 , T ] × E → E$ is a Carathéodory function; that is, $t ↦ f ( t , u )$ is strongly measurable for all $u ∈ E$, $u ↦ f ( t , u )$ is continuous for a.e. $t ∈ [ 0 , T ]$, and there exist $a > 0$ and $c · ∈ L P ( [ 0 , T ] , R + )$ such that $a M T < 1 − M ∑ 0 < t k < T c k$ and\n$∥ f ( t , u ) ∥ ≤ c ( t ) + a ∥ u ∥ , t ∈ [ 0 , T ] , u ∈ E ,$\nwhere $p ≥ 1$.\n(b) For each bounded set $B ⊂ E$ there exist $γ B · ∈ L 1 ( [ 0 , T ] , R + )$ such that (7) holds and\n$χ ( f ( t , B ) ) ≤ γ B ( t ) χ ( B ) a . e . o n [ 0 , T ] .$\nThen it is known (see , Theorem 3.1) that the operator $C$, defined by $( C u ) ( t ) : = f ( t , u ( t ) )$, $t ∈ [ 0 , T ]$, is a continuous operator from $L p ( [ 0 , T ] , E )$ into $L p ( [ 0 , T ] , E )$, and thus it is continuous from $P C ( [ 0 , T ] , E )$ into $L p ( [ 0 , T ] , E )$. Moreover, $C$ is a causal operator and it satisfies (H2)(a) with $ξ ( t , η ) : = c ( t ) + a η , t ∈ [ 0 , T ] ,$$η ∈ R +$. Also, it is easy to see that $C$ satisfies (H2)(b″). We obtain the following result.\nCorollary 1.\nAssume that $f : [ 0 , T ] × E → E$ satisfies (H1) and (Hf). If $A : D ( A ) ⊂ E → E$ is the generator of a $C 0$-semigroup ${ T ( t ) ; t ≥ 0 }$, then the impulsive evolution equation\n$u ′ ( t ) = A u ( t ) + f ( t , u ( t ) ) f o r t ∈ [ 0 , T ] \\ { t 1 , … , t N } u ( t k + ) = u ( t k − ) + ( I k u ) ( t k − ) u ( 0 ) = u 0 ,$\nhas at least one mild solution on $[ 0 , T ]$.\nIn the next result we show that, under the conditions (H1) and (H2), we can construct a sequence of successive approximations which converges to a mild solution of (4).\nTheorem 2.\nAssume that $C : P C ( [ 0 , T ] , E ) → L p ( [ 0 , T ] , E )$ is a continuous causal operator such that the conditions (H1) and (H2) hold. If $A : D ( A ) ⊂ E → E$ is the generator of a $C 0$-semigroup ${ T ( t ) ; t ≥ 0 }$, then there exists a sequence of functions ${ u n ( · ) } n ≥ 1$ in $P C ( [ 0 , T ] , E )$ such that $u n ( · ) − u ( · ) P C → 0$ as $n → ∞$, and $u ( · ) : [ 0 , T ] → E$ is a mild solution for (4).\nProof.\nLet $r > 0$ be such that (9) holds, and let $B 0$ and $F : B 0 → B 0$ be given by (10) and (11), respectively. We construct a sequence ${ u n ( · ) } n ≥ 1$ of functions $u n ( · ) ∈ P C ( [ 0 , T ] , E )$ as follows. Let $n ∈ N$. For each $i ∈ { 1 , 2 , … , n }$, we define\n$u n 1 ( t ) = T ( t ) u 0 , for t ∈ [ 0 , T / n ]$\nand\n$u n i ( t ) = u n i − 1 ( t ) , for t ∈ [ 0 , ( i − 1 ) T / n ] T ( t ) u 0 + ∫ 0 t − T / n T ( t − s ) ( C u n i − 1 ) ( s ) d s + ∑ 0 < t k < t − T n T ( t − t k ) ( I k u n i − 1 ) ( t k ) , for t ∈ ( ( i − 1 ) T / n , i T / n ]$\nfor $i > 1$. Obviously, $u n 1 ( t ) ≤ M u 0 ≤ r$ for $t ∈ [ 0 , T / n ]$. Let us suppose that $| | u n i ( t ) | | ≤ r$ for $t ∈ [ 0 , i T / n ]$ and $i ∈ { 1 , 2 , … , ν }$ with $ν ≤ n − 1$. Then we have\n$| | u n i + 1 ( t ) | | ≤ T ( t ) u 0 + M ∫ 0 t − T / n ( C u n i − 1 ) ( s ) d s + ∑ 0 < t k < t − T n T ( t − t k ) ( I k u n i − 1 ) ( t k ) ≤ M ∥ u 0 ∥ + ∫ 0 t − T / n ξ ( s , ∥ u n i − 1 ( s ) ∥ ) d s + M ∑ 0 < t k < t − T n c k ∥ u n i − 1 ( t k ) ∥ ≤ M ∥ u 0 ∥ + ∫ 0 t − T / n ξ ( s , r ) d s + M r ∑ 0 < t k < t − T n c k < r$\nfor all $t ∈ [ 0 , ( i + 1 ) T / n ]$. Hence, by induction on i we have that $| | u n i ( t ) | | < r$ for all $i ∈ { 1 , 2 , … , n }$ and $t ∈ [ 0 , i T / n ]$. In the following, to simplify the notation, we put $u n ( · ) = u n n ( · )$, $n ≥ 1$. By the causality of $C$ and $I k$, the sequence ${ u n ( · ) } n ≥ 1$ can be written as\n$u n ( t ) = T ( t ) u 0 if t ∈ [ 0 , T / n ] T ( t ) u 0 + ∫ 0 t − T / n T ( t − s ) ( C u n ) ( s ) d s + ∑ 0 < t k < t − T / n T ( t − t k ) ( I k u n ) ( t k − ) if t ∈ [ T / n , T ]$\nfor every $n ≥ 1$. Moreover, $u n ( · ) ∈ B 0$ for all $n ≥ 1$. Next, if $0 ≤ t ≤ T / n$, then it is easy to see that\n$∥ ( F u n ) ( t ) − u n ( t ) ∥ ≤ ∫ 0 T / n ∥ T ( t − s ) ( C u n ) ( s ) ∥ d s ≤ M ∫ 0 T / n ψ ( s ) d s .$\nIf $T / n ≤ t ≤ T ,$ then we have\n$∥ ( F u n ) ( t ) − u n ( t ) ∥ ≤ ∫ 0 t T ( t − s ) ( C u n ) ( s ) d s − ∫ 0 t − T / n T ( t − s ) ( C u n ) ( s ) d s + ∑ 0 < t k < t T ( t − t k ) ( I k u n ) ( t k − ) − ∑ 0 < t k < t − T / n T ( t − t k ) ( I k u n ) ( t k − ) ≤ ∫ t − T / n t T ( t − s ) L ( E ) ( C u n ) ( s ) d s + ∑ t − T / n < t k < t ∥ T ( t − t k ) ( I k u n ) ( t k − ) ∥ ≤ M ∫ t − T / n t ∥ ( C u n ) ( s ) ∥ d s + M ∑ t − T / n < t k < t ( I k u n ) ( t k − ) ≤ M ∫ t − T / n t ψ ( s ) d s + M ∑ t − T / n < t k < t ( I k u n ) ( t k − ) .$\nTherefore, we obtain that\n$∥ ( F u n ) ( · ) − u n ( · ) ∥ P C → 0 as n → ∞ .$\nLet $V = { u n ( · ) ; n ≥ 1 } .$ Since\n$u n ( · ) P C ≤ ∥ u n ( · ) − ( F u n ) ( · ) ∥ P C + ( F u n ) ( · ) P C ,$\nby (28) and the equicontinuity of $F ( V )$ on $[ 0 , T ]$, it follows that V is also equicontinuous on $[ 0 , T ]$. Define $V ( t ) = { u n ( t ) ; n ≥ 1 }$ for $t ∈ [ 0 , T ]$. Then by the property of the measure of non-compactness we obtain\n$χ ( V ( t ) ) ≤ χ ∫ 0 t − T / n T ( t − s ) ( C V ) ( s ) d s + ∑ 0 < t k < t − T / n T ( t − t k ) ( I k V ) ( t k ) ≤ χ ∫ 0 t T ( t − s ) ( C V ) ( s ) d s + χ ∫ t − T / n t T ( t − s ) ( C V ) ( s ) d s + χ ∑ 0 < t k < t − T / n T ( t − t k ) ( I k V ) ( t k ) .$\nLet $t ∈ [ 0 , T ]$ be fixed and let $ε > 0$. The we can find $n ( ε ) ≥ 1$ such that $∫ t − T / n t ψ ( s ) d s < ε / 2 M$ for $n ≥ n ( ε )$. Since\n$T ( t − s ) ( C u n ) ( s ) ≤ M ( C u n ) ( s ) ≤ M ψ ( s )$\nfor a.e. $s ∈ [ 0 , t ]$ and $n ≥ 1$, by Remark 1 we conclude that\n$χ ∫ t − T / n t T ( t − s ) ( C V ) ( s ) d s = χ ∫ t − T / n t T ( t − s ) ( C u n ) ( s ) d s ; n ≥ n ( ε ) ≤ 2 sup n ≥ n ( ε ) M ∫ t − T / n t ψ ( s ) d s < ε .$\nUsing the last inequality and the fact that $χ ∑ 0 < t k < t − T / n T ( t − t k ) ( I k V ) ( t k ) = 0$, we obtain that\n$χ ( V ( t ) ) ≤ χ ∫ 0 t T ( t − s ) ( C V ) ( s ) d s .$\nSince $V ( t )$ is bounded, by Lemma 3 and (H2) it follows that\n$χ ( V ( t ) ) ≤ ∫ 0 t χ T ( t − s ) ( C V ) ( s ) d s ≤ ∫ 0 t ∫ 0 s M γ V ( τ ) χ V ( τ ) d τ d s = ∫ 0 t ∫ τ t M γ V ( τ ) χ V ( τ ) d s d τ = ∫ 0 t M ( t − τ ) γ V ( τ ) χ V ( τ ) d τ ≤ ∫ 0 t M T γ V ( τ ) χ V ( τ ) d τ .$\nTherefore, for each $t ∈ [ 0 , T ]$, we have\n$v ( t ) ≤ ∫ 0 t M T γ V ( t ) v ( t ) d s$\nwhere $v ( t ) : = χ ( V ( t )$, $t ∈ [ 0 , T ]$. Then, by Gronwall’s lemma, it follows that $v ( t ) = 0$ for every $t ∈ [ 0 , T ]$, so that $χ ( V ( t ) ) = 0$ for every $t ∈ [ 0 , T ]$. Moreover, since $χ P C ( V ) = sup 0 ≤ t ≤ T χ ( V ( t ) )$, hence $χ P C ( V ) = 0$. Therefore, V is a relatively compact subset of $B 0$. Then, by the Arzela–Ascoli theorem, and extracting a subsequence if necessary, we may assume that the sequence ${ u n ( · ) } n ≥ 1$ converges uniformly on $[ 0 , T ]$ to a continuous function $u ( · ) ∈ B 0$. Since\n$∥ ( F u ) ( · ) − u ( · ) ∥ P C ≤ ∥ ( F u ) ( · ) − ( F u n ) ( · ) ∥ P C + ∥ ( F u n ) ( · ) − u n ( · ) ∥ P C + ∥ u n ( · ) − u ( · ) ∥ P C ,$\nby the continuity of $F$ and (28), we get $∥ ( F u ) ( · ) − u ( · ) ∥ P C = 0 .$ It follows that\n$u ( t ) = ( F u ) ( t ) = T ( t ) u 0 + ∫ 0 t T ( t − s ) ( C u ) ( s ) d s + ∑ 0 < t k < t T ( t − t k ) I k u ( t k )$\nfor all $t ∈ [ 0 , T ]$; that is, $u ( · )$ is a mild solution of the causal evolution Equation (4). □\n\n## 4. Applications\n\n1. Consider the following impulsive integro-differential evolution equation\n$u ′ ( t ) = A u ( t ) + ∫ 0 t K ( t , s ) f ( s , u ( s ) ) d s for a . e . t ∈ [ 0 , T ] , u ( t k + ) = u ( t k − ) + I k u ( t k − ) , k = 1 , 2 , … , N , u ( 0 ) = u 0 ,$\nwhere $f : [ 0 , T ] × E → E$ satisfies condition (Hf) and $K : [ 0 , T ] × [ 0 , T ] → L ( E )$ is strongly continuous. Put\n$( C u ) ( t ) : = ∫ 0 t K ( t , s ) f ( s , u ( s ) ) d s , t ∈ [ 0 , T ] .$\nIt is well known that $C$ defines a continuous operator from $L p ( [ 0 , T ] , E )$ into itself (see (, Proposition 9.5.2) or (, p. 160)). Then for each $u · ∈ P C ( [ 0 , T ] , E )$ we have\n$C u t ≤ ∫ 0 t K ( s , τ ) L ( E ) f ( τ , u ( τ ) ) d τ ≤ M 1 ∫ 0 t c ( τ ) + a ∥ u ( τ ) ∥ d τ ≤ ξ ( t , ∥ u ( · ) ∥ P C ) : = M 1 ∫ 0 t c ( τ ) d τ + a M 1 T ∥ u ( · ) ∥ P C ,$\nwhere $M 1 : = sup { K ( t , s ) L ( E ) ; t , s ∈ [ 0 , T ] }$. Next, if B is a bounded set in $P C ( [ 0 , T ] , E )$, then it is easy to show that $C B$ is bounded and equicontinuous on $[ 0 , T ]$ (as a subset of $P C ( [ 0 , T ] , E )$). Thus, by (25) and Theorem 1.2.2 in , we have\n$χ ( C B t ) = χ ∫ 0 t K ( t , s ) f ( s , B ( s ) ) d s ≤ ∫ 0 t χ K ( t , s ) f ( s , B ( s ) ) d s ≤ ∫ 0 t M 1 γ B ( s ) χ B ( s ) d s , t ∈ [ 0 , T ] .$\nConsequently, the operator $C$, defined by (30), is a continuous causal operator from $P C ( [ 0 , T ] , E )$ into $L p ( [ 0 , T ] , E )$ and it satisfies (24) and (8). Assume that hypotheses (H1), (Hf) hold, $∫ 0 T M 1 γ B ( t ) d t < 1 2 M T$ and $K : [ 0 , T ] × [ 0 , T ] → L ( E )$ is strongly continuous. Then, by Theorem 1, it follows that (29) has at least one mild solution in $P C ( [ 0 , T ] , E )$ provided that (5) holds.\n2. Consider the following impulsive reaction diffusion equation\n$∂ z ∂ t ( t , x ) = ∂ 2 z ∂ x 2 ( t , x ) + ∫ 0 t k ( t , s ) f ( s , z ( s , x ) ) d s , x ∈ ( 0 , π ) , t ∈ [ 0 , T ] \\ { t 1 , .. , t N } z ( t k + , x ) − z ( t k − , x ) = ∫ 0 x z ( t k − , y ) g k ( x ) d y , x ∈ ( 0 , π ) , k = 1 , … , N z ( t , 0 ) = z ( t , π ) = 0 , t ∈ [ 0 , T ] , z ( 0 , x ) = z 0 ( x ) , x ∈ ( 0 , π ) ,$\nwhere $0 = t 0 < t 1 < t 2 < … < t N < t N + 1 = T$, $z ( t k + , x ) = lim ( h , x ) → ( 0 − , x ) z ( t k + h , x )$, $z ( t k − , x ) = lim ( h , x ) → ( 0 − , x ) z ( t k + h , x )$, $f ( · , · ) : [ 0 , T ] × [ 0 , π ] → R$ and $k ( · , · ) : [ 0 , T ] × [ 0 , T ] → R$ are given functions, $z 0 ( · ) , g k ( · ) ∈ E : = L 2 [ 0 , π ]$ and $k = 1 , … , N$. Also, we assume that $π h g k − g k L 2 [ 0 , π − h ] → 0$ as $h → 0 +$ for $k = 1 , … , N$, where $π h g k t = g k t + h$. We can show that problem (31) is an abstract formulation of problem (29). For this, let\n$u ( t ) ( x ) : = z ( t , x ) , ( t , x ) ∈ [ 0 , T ] × [ 0 , π ] , ( I k u ) ( t ) ( x ) : = ∫ 0 x u ( t ) ( y ) g k ( x ) d y , ( t , x ) ∈ [ 0 , T ] × [ 0 , π ] , k = 1 , 2 , … , N , ( C u ) ( t ) : = ∫ 0 t K ( t , s ) F ( s , u ( s ) ) d s , t ∈ [ 0 , T ] ,$\nwhere $F ( · , · ) : [ 0 , T ] × E → E$ is given by $F ( t , u ( · ) ) x : = f ( t , z ( · , x ) )$ for $( t , x ) ∈ [ 0 , T ] × [ 0 , π ]$, and $K ( · , · ) : [ 0 , T ] × [ 0 , T ] → L ( E )$ is given by $( K ( t , s ) u ( · ) ) ( x ) : = k ( t , s ) u ( · ) ( x ) = k ( t , s ) z ( · , x )$ for $t , s ∈ [ 0 , T ]$, $x ∈ [ 0 , π ]$. Next, let $t ≥ 0$ and let us define $T ( t ) : E → E$ by\n$T ( t ) u · x : = ∑ n = 0 ∞ a n u · e − n 2 t sin n x$\nfor each $u · ∈ E$, where\n$a n u · = 2 π ∫ 0 π u · ( x ) sin n x d x .$\nThen it is known (see (, Problem 4.2 and Problem 7.8)) that ${ T ( t ) , t ≥ 0 }$ is a compact $C 0$-semigroup and its infinitesimal generator $A : D ( A ) ⊂ E → E$ is given by\n$A u · ( x ) = − ∑ n = 1 ∞ n 2 a n u · sin n x , u · ∈ D ( A ) ,$\nwhere $D ( A )$ is the space of all functions $u · ∈ E$ such that $u · , u ′ ·$ are absolutely continuous, $u ″ · ∈ E$ and $u · ( 0 ) = u · ( π ) = 0$. Also, there exists $M > 1$ such that $T ( t ) L ( E ) ≤ M$ for $t ∈ [ 0 , T ]$. From the above it follows that (31) can be written in the abstract form (29). Now, assume that\n(f)$f ( · , · ) : [ 0 , T ] × [ 0 , π ] → R$ is a Carathéodory function; that is, $t ↦ f ( t , x )$ is measurable for all $x ∈ [ 0 , π ]$, $x ↦ f ( t , x )$ is continuous for a.e. $t ∈ [ 0 , T ]$, and there exist $a > 0$ and $c · ∈ L 2 ( [ 0 , T ] , R + )$\n$∥ f ( t , x ) ∥ ≤ c ( t ) + a ∥ x ∥ , t ∈ [ 0 , T ] , x ∈ [ 0 , π ] .$\n(k)$k ( · , · ) : [ 0 , T ] × [ 0 , T ] → R$ is continuous.\nThen it is easy to check that $F ( · , · )$ verifies the condition (Hf) and $K ( · , · )$ is strongly continuous. Since ${ T ( t ) , t ≥ 0 }$ is a compact $C 0$-semigroup, for any bounded set $B ⊂ P C ( [ 0 ,$T$] , E )$, we have $χ ( T ( t ) ( C B ) ( t ) ) = 0$ for $t ∈ [ 0 , T ]$. It remains to show that $I k$ is a compact operator for each $k = 1 , … , N$. For this, we must show that for any bounded set $B ⊂ P C ( [ 0 ,$T$] , E )$, $I k B$ is equicontinuos and $I k B ( t ) ⊂ L 2 [ 0 , T ]$ is relatively compact for every $t ∈ [ 0 , T ]$. For any $u · , v · ∈ B$, using Hölder’s inequality, we have\n$I k u ( t ) − I k v ( t ) L 2 [ 0 , T ] = ∫ 0 x u ( t ) ( y ) g k ( x ) d y − ∫ 0 x v ( t ) ( y ) g k ( x ) d y L 2 [ 0 , T ] ≤ ∫ 0 x u ( t ) ( y ) − v ( t ) ( y ) g k ( x ) L 2 [ 0 , T ] d y ≤ ∫ 0 π ∫ 0 π u ( t ) ( y ) − v ( t ) ( y ) 2 g k ( x ) 2 d x 1 / 2 d y = ∫ 0 π u ( t ) ( y ) − v ( t ) ( y ) d y g k L 2 [ 0 , T ] ≤ ∫ 0 π d y 1 / 2 ∫ 0 π u ( t ) ( y ) − v ( t ) ( y ) 2 d y 1 / 2 g k L 2 [ 0 , T ] = π g k L 2 [ 0 , T ] u ( t ) − v ( t ) L 2 [ 0 , T ] ,$\nthat is,\n$I k u ( t ) − I k v ( t ) L 2 [ 0 , T ] ≤ c k u ( t ) − v ( t ) L 2 [ 0 , T ] ,$\nfor every $u · , v · ∈ B$, where $c k = π g k L 2 [ 0 , T ]$. From the above inequality it follows that\n$I k u − I k v P C ≤ c k u − v P C$\nfor every $u · , v · ∈ B$, and so, $I k B$ is equicontinuous. Using the compactness result from (, p. 74), $I k B ( t ) ⊂ L 2 [ 0 , T ]$ is relatively compact if and only if $I k B ( t )$ is bounded and\n$π h I k u ( t ) − I k u ( t ) L 2 [ 0 , π − h ] → 0 as h → 0 +$\nfor every $u · ∈ B$. The boundedness of $I k B ( t )$ follows from (32) and the definition of the causal operator. More exactly, we have that\n$I k u ( t ) L 2 [ 0 , T ] ≤ c k u ( t ) L 2 [ 0 , T ] ≤ c k u P C < c r$\nfor every $u · ∈ B$, where $r : = sup u · ∈ B u P C$ and $c : = ∑ k = 1 N c k$.\nUsing the Hölder inequality it is not difficult to show that\n$π h I k u ( t ) − I k u ( t ) L 2 [ 0 , π − h ] = ∫ 0 π − h I k u ( t ) ( x + h ) − I k u ( t ) ( x ) 2 d x 1 / 2 = ∫ 0 π − h ∫ 0 x + h u ( t ) y g k ( x + h ) d y − ∫ 0 x u ( t ) y g k ( x ) d y 2 d x 1 / 2 = ∫ 0 π − h ∫ 0 x u ( t ) y g k ( x + h ) − g k ( x ) d y + ∫ x x + h u ( t ) y g k ( x + h ) d y 2 d x 1 / 2 ≤ 2 π u P C π h g k − g k L 2 [ 0 , π − h ] + 2 ∫ x x + h u ( t ) y d y g k ( · + h ) L 2 [ 0 , π − h ] .$\nUsing the last estimation and the fact that $π h g k − g k L 2 [ 0 , π − h ] → 0$ as $h → 0 +$, we obtain (33). Since, for each $k = 1 , … , N$, we showed that for any bounded set $B ⊂ P C ( [ 0 ,$T$] , E )$, $I k B$ is equicontinuous and $I k B ( t ) ⊂ L 2 [ 0 , T ]$ is relatively compact for every $t ∈ [ 0 , T ]$, it follows that $I k$ is a compact operator for each $k = 1 , … , N$. Consequently, if $2 M c < 1$, then all the conditions of Theorem 1 are satisfied, so that (31) has a solution $z · , ·$ on $[ 0 , T ] × [ 0 , π ]$.\n\n## 5. Conclusions\n\nThe theory of impulsive evolution differential equations with causal operators is an important one because it covers a large class of different types of impulsive evolution differential equations. The study of these evolution equations hopefully will be continued with impulsive evolution equations with nonlinear operators or impulsive evolution differential inclusions involving causal operators. 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Agarwal, Vasile Lupulescu, and Donal O’Regan. 2020. \"Impulsive Evolution Equations with Causal Operators\" Symmetry 12, no. 1: 48. https://doi.org/10.3390/sym12010048\n\nNote that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here."
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https://notebook.community/AutuanLiu/Python/fastai_notes/LinearAlgebra/speech04 | [
"## PageRank\n\n#### Ways to think about SVD\n\n• Data compression\n• SVD trades a large number of features for a smaller set of better features\n• All matrices are diagonal (if you use change of bases on the domain and range)\n\nRelationship between SVD and Eigen Decomposition: the left-singular vectors of A are the eigenvectors of \\$AA^T\\$. The right-singular vectors of A are the eigenvectors of \\$A^T A\\$. The non-zero singular values of A are the square roots of the eigenvalues of \\$A^T A\\$ (and \\$A A^T\\$).\n\nSVD is a generalization of eigen decomposition. Not all matrices have eigen values, but ALL matrices have singular values.\n\nA Hermitian matrix is one that is equal to it's own conjugate transpose. In the case of real-valued matrices (which is all we are considering in this course), Hermitian means the same as Symmetric.\n\nRelevant Theorems:\n\n• If A is symmetric, then eigenvalues of A are real and \\$A = Q \\Lambda Q^T\\$\n• If A is triangular, then its eigenvalues are equal to its diagonal entries\n\n• 确定图中顶点的相对重要性的经典方法是计算邻接矩阵的主特征向量,以便将每个顶点的第一特征向量的分量值分配为中心性分数\n\n``````\n\nIn :\n\n#@title Power iteration\nimport numpy as np\n\ndef power_iteration(A, num_simulations):\n# Ideally choose a random vector\n# To decrease the chance that our vector\n# Is orthogonal to the eigenvector\nb_k = np.random.rand(A.shape)\n\nfor _ in range(num_simulations):\n# calculate the matrix-by-vector product Ab\nb_k1 = np.dot(A, b_k)\n\n# calculate the norm\nb_k1_norm = np.linalg.norm(b_k1)\n\n# re normalize the vector\nb_k = b_k1 / b_k1_norm\n\nreturn b_k\n\npower_iteration(np.array([[0.5, 0.5], [0.2, 0.8]]), 100)\n\n``````\n``````\n\nIn :\n\n# 稀疏矩阵\nimport numpy as np\nfrom scipy import sparse\ndef power_method(A, max_iter=100):\nn = A.shape\nA = np.copy(A)\nA.data /= np.take(A.sum(axis=0).A1, A.indices)\n\nscores = np.ones(n, dtype=np.float32) * np.sqrt(A.sum()/(n*n)) # initial guess\nfor i in range(max_iter):\nscores = A @ scores\nnrm = np.linalg.norm(scores)\nscores /= nrm\nprint(nrm)\n\nreturn scores\n\n``````\n``````\n\nIn :\n\nx = np.matrix(np.arange(12).reshape((3,4)))\na = sparse.csr_matrix(x, dtype=np.float32)\npower_method(a, max_iter=10)\n\n``````\n``````\n\nIn :\n\n``````\n``````\n\nIn :\n\nnp.random.randn(2, 4)\n\n``````\n• numpy.matrix.A1\n\nReturn self as a flattened ndarray. Equivalent to np.asarray(x).ravel()\n\n``````\n\nIn :\n\nx = np.matrix(np.arange(12).reshape((3,4)))\n\n``````\n``````\n\nIn :\n\nx\n\n``````\n``````\n\nIn :\n\nx.A1\n\n``````\n``````\n\nIn :\n\nx.ravel()\n\n``````\n``````\n\nIn :\n\nx.A1.shape, x.ravel().shape\n\n``````\n\n### How to normalize a sparse matrix\n\n``````\n\nIn :\n\nfrom scipy import sparse\nS = sparse.csr_matrix(np.array([[1,2],[3,4]]))\nS\n\n``````\n``````\n\nIn :\n\nSr = S.sum(axis=0).A1\nSr\n\n``````\n``````\n\nIn :\n\nS.indices\n\n``````\n``````\n\nIn :\n\nS.data\n\n``````\n``````\n\nIn :\n\nS.data / np.take(Sr, S.indices)\n\n``````\n``````\n\nIn :\n\nnp.take(Sr, S.indices)\n\n``````\n\n### QR 分解\n\n``````\n\nIn :\n\nfrom numba import jit\n@jit()\ndef pure_qr(A, max_iter=50000):\nAk = np.copy(A)\nn = A.shape\nQQ = np.eye(n)\nfor k in range(max_iter):\nQ, R = np.linalg.qr(Ak)\nAk = R @ Q\nQQ = QQ @ Q\nif k % 100 == 0:\nprint(Ak)\nprint(\"\\n\")\nreturn Ak, QQ\n\n``````\n``````\n\nIn :\n\nn = 6\nA = np.random.rand(n,n)\nAT = A @ A.T\n\n``````\n``````\n\nIn :\n\nAk, Q = pure_qr(A)\n\n``````\n``````\n\nIn :\n\n# 特征值\nnp.linalg.eigvals(A)\n\n``````\n``````\n\nIn :\n\n# Q 是正交的\nnp.allclose(np.eye(n), Q @ Q.T), np.allclose(np.eye(n), Q.T @ Q)\n\n``````\n``````\n\nIn :\n\n``````\n\nThe Arnoldi Iteration is two things:\n\n1. the basis of many of the iterative algorithms of numerical linear algebra\n2. a technique for finding eigenvalues of nonhermitian matrices (Trefethen, page 257)\n\nHow Arnoldi Locates Eigenvalues\n\n1. Carry out Arnoldi iteration\n2. Periodically calculate the eigenvalues (called Arnoldi estimates or Ritz values) of the Hessenberg H, using the QR algorithm\n3. Check at whether these values are converging. If they are, they're probably eigenvalues of A.\n``````\n\nIn :\n\n# Decompose square matrix A @ Q ~= Q @ H\ndef arnoldi(A):\nm, n = A.shape\nassert(n <= m)\n\n# Hessenberg matrix\nH = np.zeros([n+1,n]) #, dtype=np.float64)\n# Orthonormal columns\nQ = np.zeros([m,n+1]) #, dtype=np.float64)\n# 1st col of Q is a random column with unit norm\nb = np.random.rand(m)\nQ[:,0] = b / np.linalg.norm(b)\nfor j in range(n):\nv = A @ Q[:,j]\nfor i in range(j+1):\n#This comes from the formula for projection of v onto q.\n#Since columns q are orthonormal, q dot q = 1\nH[i,j] = np.dot(Q[:,i], v)\nv = v - (H[i,j] * Q[:,i])\nH[j+1,j] = np.linalg.norm(v)\nQ[:,j+1] = v / H[j+1,j]\n\n# printing this to see convergence, would be slow to use in practice\nprint(np.linalg.norm(A @ Q[:,:-1] - Q @ H))\nreturn Q[:,:-1], H[:-1,:]\n\n``````\n``````\n\nIn :\n\nQ, H = arnoldi(A)\n\n``````\n``````\n\nIn :\n\nH\n\n``````\n``````\n\nIn :\n\nQ\n\n``````\n``````\n\nIn :\n\nn = 10\nA0 = np.random.rand(n,n)\nA = A0 @ A0.T\n\n``````\n``````\n\nIn :\n\nnp.linalg.eigvals(A)\n\n``````"
] | [
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https://pubs.geoscienceworld.org/geophysics/article-abstract/59/11/1680/106537/electromagnetic-response-of-a-discretely-grounded?redirectedFrom=fulltext | [
"## Abstract\n\nWe derive an integral equation to describe the electromagnetic response of a discretely grounded circuit. This investigation is relevant to the study of man-made structures such as metallic fences, grounded powerlines, and pipelines, all of which may fall into the class of discretely grounded conductors. The solution developed here is an extension to existing circuit theory and takes into account the self and mutual interaction of the circuit elements. It is possible to ignore these interactions at low frequencies where the grounding impedances dominate the effective impedance of the circuit. However, at frequencies where the electromagnetic skin depth is comparable to the length between adjacent grounding points, the effective impedance of the circuit is proportional to frequency, and the inductance of the circuit dominates its electromagnetic response. Within the quasi-static limit (i.e., where displacement currents can be neglected) electromagnetic excitation by either horizontal electric or vertical magnetic dipoles produces a constant primary electric field at high frequencies (far-field). Thus, the electric current in the discretely grounded circuit will always be inversely proportional to frequency for these types of sources. Horizontal magnetic dipole or vertical electric dipole sources generate primary electric fields that are proportional to the inverse square root of frequency in the high frequency limit of the quasi-static domain, and thus the current in a circuit excited by such sources will decrease as the inverse of square root of frequency. The integral equation solution derived here can be used to investigate the influence from cultural conductors on actual electromagnetic surveys and also provides further insights into the current channeling response of surficial conductors.\n\nThis content is PDF only. Please click on the PDF icon to access.\n\n### First Page Preview",
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"https://gsw.silverchair-cdn.com/gsw/Content_public/Journal/geophysics/59/11/10.1190_1.1443556/5/1680.pdf.gif",
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.91081303,"math_prob":0.9748331,"size":1832,"snap":"2019-13-2019-22","text_gpt3_token_len":310,"char_repetition_ratio":0.13785557,"word_repetition_ratio":0.007662835,"special_character_ratio":0.15938865,"punctuation_ratio":0.06896552,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9701358,"pos_list":[0,1,2,3,4],"im_url_duplicate_count":[null,2,null,2,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-03-26T07:06:06Z\",\"WARC-Record-ID\":\"<urn:uuid:89d7dda7-b269-4079-bcfc-9bb124161cd3>\",\"Content-Length\":\"84486\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:8530f4d6-4699-4d20-9a4b-ad182d0e9782>\",\"WARC-Concurrent-To\":\"<urn:uuid:211ad197-0f94-4b50-96d8-d8f1c1b62d7e>\",\"WARC-IP-Address\":\"209.135.222.216\",\"WARC-Target-URI\":\"https://pubs.geoscienceworld.org/geophysics/article-abstract/59/11/1680/106537/electromagnetic-response-of-a-discretely-grounded?redirectedFrom=fulltext\",\"WARC-Payload-Digest\":\"sha1:7IXW5JEBKLMDEPVT5SKQP6MJKU7XTAI7\",\"WARC-Block-Digest\":\"sha1:E65BE6UHLXHW4YJYXDEIMILA7BNJJVEA\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-13/CC-MAIN-2019-13_segments_1552912204857.82_warc_CC-MAIN-20190326054828-20190326080828-00161.warc.gz\"}"} |
https://socratic.org/questions/how-do-you-graph-the-conic-x-2-4xy-y-2-1-0-by-first-rotations-the-axis-and-elimi | [
"# How do you graph the conic x^2-4xy+y^2+1=0 by first rotations the axis and eliminating the xy term?\n\nJan 28, 2017\n\n#### Explanation:\n\nA conic equation of the type of $A {x}^{2} + B x y + C {y}^{2} + D x + E y + F = 0$ is rotated by an angle $\\theta$, to form a new Cartesian plane with coordinates $\\left(x ' , y '\\right)$, if $\\theta$ is appropriately chosen, we can have a new equation without term $x y$ i.e. of standard form.",
null,
"The relation between coordinates $\\left(x , y\\right)$ and $\\left(x ' . y '\\right)$ can be expressed as\n$x = x ' \\cos \\theta - y ' \\sin \\theta$ and $y = x ' \\sin \\theta + y ' \\cos \\theta$\n\nor $x ' = x \\cos \\theta + y \\sin \\theta$ and $y = - x \\sin \\theta + y \\cos \\theta$\n\nfor this we need to have $\\theta$ given by $\\cot 2 \\theta = \\frac{A - C}{B}$\n\nIn the given case as equation is ${x}^{2} - 4 x y + {y}^{2} + 1 = 0$, we have $A = C = 1$ and $B = - 4$ and hence $\\cot 2 \\theta = 0$ i.e. $\\theta = \\frac{\\pi}{4}$\n\nHence relation is give by $x = x ' \\cos \\left(\\frac{\\pi}{4}\\right) - y ' \\sin \\left(\\frac{\\pi}{4}\\right)$ and $y = x ' \\sin \\left(\\frac{\\pi}{4}\\right) + y ' \\cos \\left(\\frac{\\pi}{4}\\right)$ i.e.\n\n$x = \\frac{x '}{\\sqrt{2}} - \\frac{y '}{\\sqrt{2}}$ and $y = \\frac{x '}{\\sqrt{2}} + \\frac{y '}{\\sqrt{2}}$\n\nHence, we get ${\\left(\\frac{x '}{\\sqrt{2}} - \\frac{y '}{\\sqrt{2}}\\right)}^{2} - 4 \\left(\\frac{x '}{\\sqrt{2}} - \\frac{y '}{\\sqrt{2}}\\right) \\left(\\frac{x '}{\\sqrt{2}} + \\frac{y '}{\\sqrt{2}}\\right) + {\\left(\\frac{x '}{\\sqrt{2}} + \\frac{y '}{\\sqrt{2}}\\right)}^{2} + 1 = 0$\n\nor $\\left(\\frac{x {'}^{2}}{2} + \\frac{y {'}^{2}}{2} - x ' y '\\right) - 4 \\left(\\frac{x {'}^{2}}{2} - \\frac{y {'}^{2}}{2}\\right) + \\left(\\frac{x {'}^{2}}{2} + \\frac{y {'}^{2}}{2} + x ' y '\\right) + 1 = 0$\n\nor $- x {'}^{2} + 3 y {'}^{2} + 1 = 0$ or $x {'}^{2} - 3 y {'}^{2} = 1$\n\nThe two graphs are as follows:\ngraph{x^2-4xy+y^2+1=0 [-10, 10, -5, 5]}\nand\ngraph{x^2-3y^2=1 [-10, 10, -5, 5]}"
] | [
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https://www.abcbnews.com/fd-interest-calculator-everything-you-need-to-know/ | [
"",
null,
"# FD Interest Calculator: Everything You Need To Know\n\nFixed deposits are offered by most banking institutions and are considered a safe investment option. The FD calculator is an online tool that calculates the interest on a fixed deposit for a given period of time. For example, if you have Rs.1 lac to invest for 18 months, the FD calculator can tell you how much you will earn in interest over this period.\n\nFD might sound like a complicated subject but in reality, it is not that tricky. Opportunities aren’t easy to come by, therefore knowing about the best method of investment ensures you don’t miss out on the possible ones. It will assist you to make the right financial decision and understanding how an FD interest calculator works can be the first step in doing so.\n\n## What is an FD Interest Calculator?\n\nAn FD Interest Calculator is a helpful tool for calculating interest returns on your investment. It considers the principal investment, the interest rate, and the duration of the fixed deposit. An FD Interest calculator is a simple tool that allows you to compare which banks offer the best interest rate on FD.\n\nWealth management can be a difficult concept to grasp, especially when it comes to investing a large sum of money all at once. Using an FD Interest calculator, you can calculate the compound interest you would earn on your investment over terms ranging from 7 days to 10 years. It will ensure that you are making the best investment decision possible.\n\n### How to Determine FD Interest Amount\n\nAn FD Interest Calculator calculates the investment’s maturity value based on three factors. These variables differ from person to person because they must be decided and entered by the people themselves.\n\nFormula to calculate FD maturity amount –\n\nA = P * (1+ r/n) n*t,\n\nA = Value of Maturity\n\nI = A – P\n\nP = principal sum\n\nr = interest rate\n\nn = compound interest rate\n\nt = number of years\n\nI = total interest earned\n\nHere is an example to better understand how an FD maturity amount is calculated –\n\nSuppose you deposit Rs. 50,000 that is held for three years at a quarterly compounding interest rate of 10% then the interest earned at maturity would be:\n\nA= 50,000 {1 + (0.1/4)} ^ (4 * 3)\n\nA = 50,000 (1 + 0.025) ^ (12)\n\nA = 50,000 (1.025) ^ (12)\n\n= Rs. 67,244 (approximately)\n\nCI = Maturity Amount – Principal Amount\n\nCI = 67,244 – 50,000\n\n= Rs. 17,244\n\nAn online FD maturity calculator works on the above-mentioned mathematical formula.\n\n## How To Use FD Interest Calculator Online?\n\nFD interest calculator is very easy to use. Here’s how you can calculate the amount using it:\n\nStep 1: Search for an FD interest calculator online.\n\nStep 2: Enter your principal amount, interest rate, and tenure.\n\nStep 3: The maturity value and interest returns will be displayed on the screen.\n\n### What is FD?\n\nA Fixed Deposit or FD is a financial tool that allows you to save money. FD can be used for a variety of things. It can help you save for your dream home, set aside money for your child’s future, or be prepared for financial emergencies. Owning a fixed deposit account can benefit you in a variety of ways.\n\nYou can open an FD account for as little as 7 days and as much as 10 years. Also, you can choose to receive the maturity value regularly or all at once at the end of the term. However, if you withdraw funds from your fixed deposit account before it matures, you will be required to pay a penalty.\n\n#### Features of an FD\n\nHaving an FD comes with many benefits –\n\n• You will receive the maturity value guaranteed to you regardless of market fluctuations in interest\n• Your FD’s interest rate is fixed. The interest rate is determined by the term plan you select when you open your account.\n• The terms of FD are flexible. You can open a fixed deposit account for as little as 7 days and as much as 10 years.\n• If you choose a longer tenure, you will receive higher returns on your investment.\n• You can choose to receive the maturity value regularly or at the end of the term.\n• You can also choose to reinvest the interest. It is also referred to as cumulative FD.\n• Senior citizens benefit from FD accounts because they earn higher interest rates.\n• In case of an emergency, you can borrow against your fixed deposit account.\n\nOne should research extensively before investing in a related decision. Therefore, it is essential to understand how an FD interest calculator works to help ease your decision-making regarding FDs.\n\nShare"
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.9354134,"math_prob":0.9610339,"size":4351,"snap":"2022-40-2023-06","text_gpt3_token_len":956,"char_repetition_ratio":0.15297906,"word_repetition_ratio":0.04859335,"special_character_ratio":0.2319007,"punctuation_ratio":0.09367681,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.98221076,"pos_list":[0,1,2],"im_url_duplicate_count":[null,1,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-02-09T10:06:58Z\",\"WARC-Record-ID\":\"<urn:uuid:ef763ac9-5ec9-4e74-8514-e010793d0c92>\",\"Content-Length\":\"105042\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:245f07ed-e131-46de-930f-5e8b9941b60f>\",\"WARC-Concurrent-To\":\"<urn:uuid:b32a1ee5-1557-40bf-a4fd-2dee7b8b5c7b>\",\"WARC-IP-Address\":\"199.188.206.3\",\"WARC-Target-URI\":\"https://www.abcbnews.com/fd-interest-calculator-everything-you-need-to-know/\",\"WARC-Payload-Digest\":\"sha1:7A6ERKSUQNBTR5LBSFUPSHJA6CPSRANK\",\"WARC-Block-Digest\":\"sha1:B5M662LRL2XNG6GOI7BGDDZ3WVIEYHR5\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-06/CC-MAIN-2023-06_segments_1674764501555.34_warc_CC-MAIN-20230209081052-20230209111052-00438.warc.gz\"}"} |
https://cstheory.stackexchange.com/questions/45668/cover-set-of-boolean-formulas-with-conjunctions | [
"# Cover set of Boolean formulas with conjunctions\n\nI want to cover a set of Boolean formulas (over the same variables) with disjunctive conjunctions. Here's an example with two formulas $$p_1$$ and $$p_2$$ over the set of variables $$\\{A, B, X, Y\\}$$:",
null,
"I want to partition the solution space into conjunctions and represent all formulas as disjunctions of such conjunctions:",
null,
"In the left example, the solution space is partitioned into five conjunctions. Both $$p_1$$ and $$p_2$$ can be represented as disjunctions of these conjunctions, as shown. Note that not every conjunction appears in a disjunction. However, it is still needed to partition the solution space.\n\nI am looking for such a partition with the minimal number of conjunctions. So although the partition on the right also admits a representation as disjunctions, it consists of six conjunctions and is therefore not minimal.\n\nIs this a solved problem? I am interested in both structural and algorithmic results.\n\n• aren't you just looking for prime implicants? – holf Oct 10 at 8:47\n• @holf It seems like prime implicants are defined for a single formula. I'm looking for a similar concept, but for multiple formulas. – madbeebop Oct 10 at 16:40\n• yeah but then they are the prime implicant of the disjunction of your formulas aren't they? – holf Oct 10 at 22:44\n• @holf Not necessarily, are they? Say you had a third formula $p_3 = (\\neg A \\land \\neg X \\land B)$, then $p_2$ would be a prime implicant and $p_3$ is not represented. – madbeebop Oct 11 at 17:27"
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https://www.armoredpenguin.com/wordsearch/Data/2012.12/1411/14113803.469.html | [
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"### Ken Kovacs\n\nWords about the fundamental properties that have not changed in the past 7 billion years. There was been an astronomy observations from the University Of Amsterdam. The other group was Max Planck Institute radio astronomy telescope. Dealing with molecules plus matter.\n\n d i s c o v e r t s m a t s p e c t r u m e n s n m q u a n t u m e m a l c o h o l i t l t a p r o t o n s l f s e r a t i o n e t e t p a r a m e t e r s c a e h e g s r s p t u f a n r o e s e i t d s m n a t n f r e q u e n c y r c q n r i p a r l e a s t r o n o m y g d o u g o o e e a a i l h b e t d b r o t a p e u n c c f u y n o u i m e a s u r e m e n t s h t f n e a c n l e s m e t m o l e c u l a r e i a o a d l t t e r r e s t r i a l r a l v r o l r i e e n v i r o n m e n t a l s e s o e e o r l t a m t m a s s e r c s b r t r m d n b e a t g t p r o p e r t i e s r e e i s e s l i n t e n s i t y e s r i u o t s t h c c o n s t a n t e e r t g t c t h t c i o u n i v e r s a l h i c i y t i a a y b p t s c i e n t i s t s l r s u c n n i i e r a p h y s i c i s t s t e r r o t a t i o n i y i a i n s t i t u t e p l a n c k m p t h e o r e t i c a l l y\n alcohol amsterdam astronomy billion characteristic constant discover distant effelsberg einstein electrons environmental exhibit exotic frequencies frequency fundamental galaxy hundred institute intensity internal local mass matter max measurements meter methanol molecular observations parameter passing physicists planck properties protons quantum radio ratio rotation scientists spectral spectrum structure telescope telescope terrestrial test theoretically universal university years\n\nSome of the puzzles that people list for the public get indexed by the search engines (like Google). Some people find those puzzles and cannot figure out how to make a puzzle of their own. So this page now has the navigation sidebar.\n\nThere are now buttons on the puzzle so that you can get a clean page, in either HTML or PDF, that you can use your browser's print button to print. The PDF format allows the web site to know how large a printer page is, and the fonts are scaled to fill the page. The PDF takes awhile to generate. Don't panic!",
null,
"Web armoredpenguin.com"
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"https://www.armoredpenguin.com/wordsearch/Images/home.png",
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"https://www.armoredpenguin.com/wordsearch/Images/mypuzzles.png",
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"https://www.armoredpenguin.com/wordsearch/Images/faq.png",
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"https://www.armoredpenguin.com/wordsearch/Images/bug.png",
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"https://www.armoredpenguin.com/wordsearch/Images/bestof.png",
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"https://www.armoredpenguin.com/wordsearch/Images/random.png",
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"https://www.armoredpenguin.com/wordsearch/Images/login.png",
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"https://www.google.com/logos/Logo_25wht.gif",
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.5461153,"math_prob":0.9924818,"size":2731,"snap":"2021-31-2021-39","text_gpt3_token_len":1211,"char_repetition_ratio":0.21818848,"word_repetition_ratio":0.0030959751,"special_character_ratio":0.42694983,"punctuation_ratio":0.021212121,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9980199,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18],"im_url_duplicate_count":[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-09-27T13:11:23Z\",\"WARC-Record-ID\":\"<urn:uuid:3e628420-f118-4309-a19e-9ffbaf97e5e1>\",\"Content-Length\":\"56862\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:68819e83-bd4b-4d37-bf98-022194f32a77>\",\"WARC-Concurrent-To\":\"<urn:uuid:7bb7edd2-79ed-4519-88cc-968a107fedf4>\",\"WARC-IP-Address\":\"69.59.217.194\",\"WARC-Target-URI\":\"https://www.armoredpenguin.com/wordsearch/Data/2012.12/1411/14113803.469.html\",\"WARC-Payload-Digest\":\"sha1:QQW3Z37ZD3L6PSCMFWONMRHKSAK72ERK\",\"WARC-Block-Digest\":\"sha1:DNRVCBG2Z6AXIWNPGLW5ZDWG4RRBIIW3\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-39/CC-MAIN-2021-39_segments_1631780058450.44_warc_CC-MAIN-20210927120736-20210927150736-00327.warc.gz\"}"} |
https://stackoverflow.com/questions/58488270/get-weights-of-a-graph-from-different-process/58491875 | [
"# Get weights of a graph from different process\n\nI create multiple copies of a master model , each in a different process in order to get the gradients of each separately and apply them all to the master model en masse. (I'm testing it with only one child process for now (worker):\n\n``````num_workers = 1\nmaster = ACNetwork() # Creates the network\nenvs = [gym.make('CartPole-v0') for i in range(num_workers)]\n# the environment that gives me data to train on\nworkers = [Worker(number=i, environment=envs[i], master_network=master,\ncounter=counter) for i in range(num_workers)]\nfor worker in workers:\nworker.start()\n``````\n\nMy problem is that I create the master model in the parent process, pass it as an argument to every child process and getting the weights raises a value error :\n\n``````# The worker executes\ndef run(self):\nwith tf.Session(graph=tf.Graph()) as sess:\nself.private_net = ACNetwork()\n.......\n``````\n``````# now inside the master network\n# get_weights raises the error\n``````\n\nraises:\n\n``````ValueError: Tensor Tensor(\"dense_4/kernel:0\", shape=(4, 512), dtype=float32_ref) is not an element of this graph\n``````\n\nFrom my understanding the code of updating weights is executed inside a graph that doesn't entail the master network thus raising the error. How can I preserve the master network's graph so that I can update it in the context of the child process?\n\nYou must create the model in each of the processes and set equal weights, and keep the models there without closing the processes. You will need to control the train flow between them, making the processes wait for the main thread and vice-versa. This is probably way too hard and there are other options.\n\nYou don't need processes to pass parallel batches, you can make a parallel model:\n\n``````mainModel = ....\n\ninputs = []\noutputs = []\nfor i in range(num_workers):\ninp = Input(input_shape)\nout = mainModel(inp)\ninputs.append(inp)\noutputs.append(out)\n\nparallelModel = Model(inputs, outputs)\n``````\n\nTrain with `num_workers` different groups of data:\n\n``````parallelModel.fit(\n[xTrain1, xTrain2,...],\n[yTrain1, yTrain2,...]\n)\n``````\n\nIf you are using eager execution, even without a parallel model or other processes, you can pass `num_workers` batches, calculate their gradients, sum their gradients and finally apply gradients.\n\nIf you really want to use parallel processing without creating the suggested parallel model, you should probably use `multiprocessing.dummy` and keep one single model in the main thread, using the workers only to pass data and get gradients.\n\nNow, even simpler, using a batch size that is `num_workers` times the size of each of your parallel batches will result in the same thing.\n\n• Hey daniel. If I understand correctly what you are saying then there is a problem in that your fit is done sequentially, only the gathering of the data is done parallely. In my description , gathering data and computing gradients is done parallely. It is the application of the gradients that is done synchronously. Basically I can't use .fit() at all, unless you are implying something different in which case please correct me – Makis Kans Oct 21 at 18:55\n• The first example in my answer processes 4 parallel batches in the same model. The resulting gradients is the same as the sum of 4 parallel different gradient calculations with those batches. – Daniel Möller Oct 22 at 12:34\n• Oh now I get what you meant. It's a great answer but it's still not asynchronous. Suppose one thread finishes gathering data, I have to wait for all to finish to call one fit, because I don't think can I call .fit() on the same model from different threads. Of course the time interval between two threads finishing gathering data will not be much , presumably for now. But still... – Makis Kans Oct 23 at 9:48\n• No threads are needed, only one fit call is necessary. – Daniel Möller Oct 27 at 0:13"
] | [
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https://www.combinatorics.org/ojs/index.php/eljc/article/view/v27i2p43 | [
"# Geometric Realization of $\\gamma$-Vectors of Subdivided Cross Polytopes\n\n• Natalie Aisbett\nFor any flag simplicial complex $\\Theta$ obtained by stellar subdividing the boundary of the cross polytope in edges, we define a flag simplicial complex $\\Delta(\\Theta)$ whose $f$-vector is the $\\gamma$-vector of $\\Theta$. This proves that the $\\gamma$-vector of any such simplicial complex is the face vector of a flag simplicial complex, partially solving a conjecture by Nevo and Petersen. As a corollary we obtain that such simplicial complexes satisfy the Frankl-Füredi-Kalai inequalities."
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https://superuser.com/users/8063/jjxtra | [
"## jjxtra\n\n``` ____==========_______\n_--____ | | \"\" \" \"| \\\n/ )8} ^^^| 0 | = | o 0 |\n=/_ +-==B vvv|\"\" | = | ' \"\" \"|\n\\_____/ |____|________|________|\n(_( )\\________/___( )__)\n|\\ \\ / /\\\n| \\ \\ / /\\ \\\n| |\\ \\ / / \\ \\\n( )( ) ( \\ ( )\n\\ / / \\ \\ \\ \\\n\\| |\\ \\ \\ | |\n| | )____ \\ \\ \\ )___\n( ) / / ( ) (/ /\n/___\\ /__/ /___\\ /__/\n```\n\nTHERE BE DRAGONS HERE!\n\n``` . _///_,\n. / ` ' '>\n) o' __/_'>\n( / _/ )_\\'>\n' \"__/ /_/\\_>\n____/_/_/_/\n/,---, _/ /\n\"\" /_/_/_/\n/_(_(_(_ \\\n( \\_\\_\\\\_ )\\\n\\'__\\_\\_\\_\\__ ).\\\n//____|___\\__) )_/\n| _ \\'___'_( /'\n\\_ (-'\\'___'_\\ __,'_'\n__) \\ \\\\___(_ __/.__,'\n,((,-,__\\ '\", __\\_/. __,'\n'\"./_._._-'\n```\n1\nanswer\n0\nquestions\n0\npeople reached\n• Sol\n• Member for 9 years, 9 months\n• 14 profile views\n• Last seen 6 hours ago\n\nScore 0\nPosts 1\nScore 0\nPosts 1\n\n2"
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.53311545,"math_prob":0.9962486,"size":1182,"snap":"2019-13-2019-22","text_gpt3_token_len":443,"char_repetition_ratio":0.101018675,"word_repetition_ratio":0.015686275,"special_character_ratio":0.6159052,"punctuation_ratio":0.096618354,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9588025,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-05-20T19:03:08Z\",\"WARC-Record-ID\":\"<urn:uuid:ccfd76e3-fbed-4972-83cb-b4e2a0f35b01>\",\"Content-Length\":\"89628\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:e7a49844-0745-4924-b709-834974aca76e>\",\"WARC-Concurrent-To\":\"<urn:uuid:795e62a5-998b-4d87-bf4b-76c4e9b7b470>\",\"WARC-IP-Address\":\"151.101.65.69\",\"WARC-Target-URI\":\"https://superuser.com/users/8063/jjxtra\",\"WARC-Payload-Digest\":\"sha1:SFFKY3E76VQKKLRMVQIWDV5AIY3BQU4Q\",\"WARC-Block-Digest\":\"sha1:SMT3JPA73DMLCEGXDSLV4GB7CNKXQY3Z\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-22/CC-MAIN-2019-22_segments_1558232256100.64_warc_CC-MAIN-20190520182057-20190520204057-00344.warc.gz\"}"} |
https://www.colorhexa.com/1a1516 | [
"# #1a1516 Color Information\n\nIn a RGB color space, hex #1a1516 is composed of 10.2% red, 8.2% green and 8.6% blue. Whereas in a CMYK color space, it is composed of 0% cyan, 19.2% magenta, 15.4% yellow and 89.8% black. It has a hue angle of 348 degrees, a saturation of 10.6% and a lightness of 9.2%. #1a1516 color hex could be obtained by blending #342a2c with #000000. Closest websafe color is: #330000.\n\n• R 10\n• G 8\n• B 9\nRGB color chart\n• C 0\n• M 19\n• Y 15\n• K 90\nCMYK color chart\n\n#1a1516 color description : Very dark (mostly black) red.\n\n# #1a1516 Color Conversion\n\nThe hexadecimal color #1a1516 has RGB values of R:26, G:21, B:22 and CMYK values of C:0, M:0.19, Y:0.15, K:0.9. Its decimal value is 1709334.\n\nHex triplet RGB Decimal 1a1516 `#1a1516` 26, 21, 22 `rgb(26,21,22)` 10.2, 8.2, 8.6 `rgb(10.2%,8.2%,8.6%)` 0, 19, 15, 90 348°, 10.6, 9.2 `hsl(348,10.6%,9.2%)` 348°, 19.2, 10.2 330000 `#330000`\nCIE-LAB 7.352, 2.679, 0.204 0.839, 0.814, 0.872 0.332, 0.322, 0.814 7.352, 2.687, 4.357 7.352, 1.569, -0.065 9.022, 0.812, 0.585 00011010, 00010101, 00010110\n\n# Color Schemes with #1a1516\n\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #151a19\n``#151a19` `rgb(21,26,25)``\nComplementary Color\n• #1a1519\n``#1a1519` `rgb(26,21,25)``\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #1a1715\n``#1a1715` `rgb(26,23,21)``\nAnalogous Color\n• #15191a\n``#15191a` `rgb(21,25,26)``\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #151a17\n``#151a17` `rgb(21,26,23)``\nSplit Complementary Color\n• #15161a\n``#15161a` `rgb(21,22,26)``\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #161a15\n``#161a15` `rgb(22,26,21)``\nTriadic Color\n• #19151a\n``#19151a` `rgb(25,21,26)``\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #161a15\n``#161a15` `rgb(22,26,21)``\n• #151a19\n``#151a19` `rgb(21,26,25)``\nTetradic Color\n• #000000\n``#000000` `rgb(0,0,0)``\n• #000000\n``#000000` `rgb(0,0,0)``\n• #0c0a0a\n``#0c0a0a` `rgb(12,10,10)``\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #282022\n``#282022` `rgb(40,32,34)``\n• #362c2e\n``#362c2e` `rgb(54,44,46)``\n• #44373a\n``#44373a` `rgb(68,55,58)``\nMonochromatic Color\n\n# Alternatives to #1a1516\n\nBelow, you can see some colors close to #1a1516. Having a set of related colors can be useful if you need an inspirational alternative to your original color choice.\n\n• #1a1517\n``#1a1517` `rgb(26,21,23)``\n• #1a1517\n``#1a1517` `rgb(26,21,23)``\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #1a1515\n``#1a1515` `rgb(26,21,21)``\n• #1a1515\n``#1a1515` `rgb(26,21,21)``\nSimilar Colors\n\n# #1a1516 Preview\n\nText with hexadecimal color #1a1516\n\nThis text has a font color of #1a1516.\n\n``<span style=\"color:#1a1516;\">Text here</span>``\n#1a1516 background color\n\nThis paragraph has a background color of #1a1516.\n\n``<p style=\"background-color:#1a1516;\">Content here</p>``\n#1a1516 border color\n\nThis element has a border color of #1a1516.\n\n``<div style=\"border:1px solid #1a1516;\">Content here</div>``\nCSS codes\n``.text {color:#1a1516;}``\n``.background {background-color:#1a1516;}``\n``.border {border:1px solid #1a1516;}``\n\n# Shades and Tints of #1a1516\n\nA shade is achieved by adding black to any pure hue, while a tint is created by mixing white to any pure color. In this example, #040304 is the darkest color, while #faf8f9 is the lightest one.\n\n• #040304\n``#040304` `rgb(4,3,4)``\n• #0f0c0d\n``#0f0c0d` `rgb(15,12,13)``\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #251e1f\n``#251e1f` `rgb(37,30,31)``\n• #302728\n``#302728` `rgb(48,39,40)``\n• #3b2f32\n``#3b2f32` `rgb(59,47,50)``\n• #45383b\n``#45383b` `rgb(69,56,59)``\n• #504144\n``#504144` `rgb(80,65,68)``\n• #5b4a4d\n``#5b4a4d` `rgb(91,74,77)``\n• #665256\n``#665256` `rgb(102,82,86)``\n• #715b5f\n``#715b5f` `rgb(113,91,95)``\n• #7c6469\n``#7c6469` `rgb(124,100,105)``\n• #876d72\n``#876d72` `rgb(135,109,114)``\nShade Color Variation\n• #91767b\n``#91767b` `rgb(145,118,123)``\n• #998186\n``#998186` `rgb(153,129,134)``\n• #a28c90\n``#a28c90` `rgb(162,140,144)``\n• #ab979b\n``#ab979b` `rgb(171,151,155)``\n• #b4a2a5\n``#b4a2a5` `rgb(180,162,165)``\n• #bcacb0\n``#bcacb0` `rgb(188,172,176)``\n• #c5b7ba\n``#c5b7ba` `rgb(197,183,186)``\n• #cec2c5\n``#cec2c5` `rgb(206,194,197)``\n• #d7cdcf\n``#d7cdcf` `rgb(215,205,207)``\n• #dfd8d9\n``#dfd8d9` `rgb(223,216,217)``\n• #e8e3e4\n``#e8e3e4` `rgb(232,227,228)``\n• #f1eeee\n``#f1eeee` `rgb(241,238,238)``\n• #faf8f9\n``#faf8f9` `rgb(250,248,249)``\nTint Color Variation\n\n# Tones of #1a1516\n\nA tone is produced by adding gray to any pure hue. In this case, #181717 is the less saturated color, while #2e010a is the most saturated one.\n\n• #181717\n``#181717` `rgb(24,23,23)``\n• #1a1516\n``#1a1516` `rgb(26,21,22)``\n• #1c1315\n``#1c1315` `rgb(28,19,21)``\n• #1e1114\n``#1e1114` `rgb(30,17,20)``\n• #1f1013\n``#1f1013` `rgb(31,16,19)``\n• #210e12\n``#210e12` `rgb(33,14,18)``\n• #230c11\n``#230c11` `rgb(35,12,17)``\n• #250a0f\n``#250a0f` `rgb(37,10,15)``\n• #27080e\n``#27080e` `rgb(39,8,14)``\n• #28070d\n``#28070d` `rgb(40,7,13)``\n• #2a050c\n``#2a050c` `rgb(42,5,12)``\n• #2c030b\n``#2c030b` `rgb(44,3,11)``\n• #2e010a\n``#2e010a` `rgb(46,1,10)``\nTone Color Variation\n\n# Color Blindness Simulator\n\nBelow, you can see how #1a1516 is perceived by people affected by a color vision deficiency. This can be useful if you need to ensure your color combinations are accessible to color-blind users.\n\nMonochromacy\n• Achromatopsia 0.005% of the population\n• Atypical Achromatopsia 0.001% of the population\nDichromacy\n• Protanopia 1% of men\n• Deuteranopia 1% of men\n• Tritanopia 0.001% of the population\nTrichromacy\n• Protanomaly 1% of men, 0.01% of women\n• Deuteranomaly 6% of men, 0.4% of women\n• Tritanomaly 0.01% of the population"
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.53491366,"math_prob":0.7995803,"size":3656,"snap":"2021-04-2021-17","text_gpt3_token_len":1662,"char_repetition_ratio":0.12322015,"word_repetition_ratio":0.011049724,"special_character_ratio":0.56400436,"punctuation_ratio":0.23496659,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9912244,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-04-20T06:44:17Z\",\"WARC-Record-ID\":\"<urn:uuid:64eb88c0-730a-4424-b1e7-c514ef6c2b00>\",\"Content-Length\":\"36196\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:4a2ed6d0-bd8e-4c31-97f4-e81bc872d1e0>\",\"WARC-Concurrent-To\":\"<urn:uuid:0243379c-590c-4681-8b5a-0a9b5d9d8abf>\",\"WARC-IP-Address\":\"178.32.117.56\",\"WARC-Target-URI\":\"https://www.colorhexa.com/1a1516\",\"WARC-Payload-Digest\":\"sha1:VSNB7LZ5HQIAHLHOU5TCRR5VLQX2DKCD\",\"WARC-Block-Digest\":\"sha1:AEDB44PXVTCUYK6JAY6E4UCS75RQES2Y\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-17/CC-MAIN-2021-17_segments_1618039379601.74_warc_CC-MAIN-20210420060507-20210420090507-00435.warc.gz\"}"} |
https://www.alphr.com/get-rid-div-0-google-sheets/ | [
"# How to Get Rid of #Div/0 in Google Sheets\n\nUsing automatic formulas in Google Sheets is more of a necessity than a choice when dealing with a large amount of data. Automation, however, can come with a few downsides, such as errors resulting from improper mathematical processes. Dividing by zero, or the #Div/0 error, is one of these.",
null,
"In this article, we’ll show you how to get rid of the #Div/0 error in Google Sheets.\n\n## Populate the Cells Properly\n\nAs mentioned above, you get a #Div/0 error if you divide anything by zero. It’s an equation that results in a mathematical impossibility and thus isn’t accepted by the program. This error can be avoided simply by making sure that no formula uses zero or a blank cell as a divisor. You can either delete or populate blank cells, or not include them in the equation at all. This method is fine if you’re managing a small number of cells, but for large automated formulas, you’ll need a catch-all code.\n\n## Using the If Error Function\n\nIf you’re using a formula to automatically calculate the values of cells, errors like #Div/0 are to be expected. What you can do rather than trying to avoid the chance of getting the error, which is difficult, is to find a way to deal with it if it does. This is where the If Error function comes into play.\n\nIf Error is a Google Sheets function that checks the values given to it, and if it returns an error then it proceeds to perform a command. The function has a syntax of =IFERROR(value, value-if-error) where:\n\n‘=’ tells Google Sheets that you’re using a function.\n\n‘IFERROR’ checks the given value results in an error.\n\n‘value’ is the process to be checked for an error.\n\n‘value-if-error’ is what is displayed if value results in an error.\n\nBasically, the If Error function will perform the process of a given value. If that process results in an error, like a division by zero, it will display what you determine as the value-if-error.\n\nFor example, if you wish to divide two cells A1 by A2, as long as both cells are properly filled, it will return the result of the division. If A2 becomes zero or is blank, then it will result in an error #Div/0. If you use the formula =Iferror(A1/A2,”Division by Zero”) then if A2 suddenly becomes blank or zero, instead of displaying an error it will display Division by Zero.",
null,
"The If Error function can also be used as the syntax =Iferror(value). This fills in value-if-error as blank and will return a blank space if an error is detected.",
null,
"As long as you use the If Error function for any automated formula that you make, you won’t encounter the #Div/0 error.\n\nThe limitation of the If Error function is that it will return the error-if-value for any error. Even if the error isn’t #Div/0, if you declared value-if-error as division by zero and it encounters a different error it will still say division by zero.",
null,
"## Using the Error.Type Function\n\nThe Error.Type function, instead of returning a value that you determine, returns an associated error code. The corresponding codes for all of the different errors are 1 for #NULL!, 2 for #DIV/0!, 3 for #VALUE!, 4 for #REF!, 5 for #NAME?, 6 for #NUM!, 7 for #N/A, and 8 for everything else.\n\nThis function is useful if you occasionally encounter errors other than divisions by zero, as this makes it easier to troubleshoot them. This, of course, requires a bit of coding knowledge to use effectively. Using just the Error.Type on its own won’t be useful as you won’t know if the number displayed is a code or an actual answer. Using both If Then statements, and the If Error function can create a formula that checks for specific errors.",
null,
"For instance, in the formula =iferror(A1/A2,if(error.type(A1/A2)=2,”Division by Zero”,”Unknown Error”)), Google Sheets will first perform the calculation a1/a2. If this is possible, then it will display an answer. If it results in an error, then it goes to the next line.\n\nHere an If Then statement will check what type of error is returned by the Error.Type function. If it returns a 2, which is the code for the #Div/0 error, then it will display Division by Zero, otherwise, it will display Unknown Error.\n\nThis can be further expanded by nested If statements for each error type if you want to. This ensures that if an error does occur in the worksheet you know exactly what error it is and how to deal with it.\n\n## Expected Errors\n\nEncountering errors such as #Div/0 are almost to be expected if you work with Google Sheets often. Handling such errors is easy as long as you know the proper functions to use.\n\nDo you have other tips on how to get rid of #Div/0 errors in Google Sheets? Share your thoughts in the comments section below.",
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"https://i0.wp.com/www.alphr.com/wp-content/uploads/2020/09/division-by-zero.jpg",
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"https://i0.wp.com/www.alphr.com/wp-content/uploads/2020/09/div0-in-google-sheets.jpg",
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"https://i0.wp.com/www.alphr.com/wp-content/uploads/2020/09/get-rid-of-div0-in-google-sheets.jpg",
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"https://i0.wp.com/www.alphr.com/wp-content/uploads/2021/07/How-to-Use-Inspect-Element.png",
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https://byjusexamprep.com/there-are-two-bags-a-and-b-a-contains-6-red-flowers-and-3-pink-flowers-whereas-bag-b-contains-2-red-flowers-and-7-pink-flowers-i | [
"# There are two bags A and B. A contains 6 red flowers and 3 pink flowers, whereas Bag B contains 2 red flowers and 7 pink flowers. One flower is chosen from a bag randomly. What is the probability that the flower chosen is pink?\n\nBy Ruchika|Updated : May 17th, 2023\n\nIn this problem, there are two bags, A and B. Bag A contains 6 red flowers and 3 pink flowers, whereas Bag B contains 2 red flowers and 7 pink flowers. If one flower is picked randomly, the probability of choosing a pink flower will be 5/9.\n\nProbability is an important concept in mathematics and it plays a crucial role in a wide range of applications. In probability, we calculate the likelihood of an event happening. The probability of an event is expressed as a number between 0 and 1, where 0 represents an impossible event and 1 represents a certain event.\n\nSolution:\n\nTo find the probability that the flower chosen is pink, we need to add the number of pink flowers in both bags and divide it by the total number of flowers in both bags.\n\nTotal number of pink flowers = Pink flowers in bag A + Pink flowers in bag B\n\n= 3 + 7 = 10 pink flowers\n\nTotal number of flowers in both bags = flowers in bag A + flowers in bag B\n\n= 6 + 3 + 2 + 7 = 18 flowers\n\nTherefore, the probability of picking a pink flower is:\n\nProbability = Total number of pink flowers / Total number of flowers\n\nProbability = 10/18 = 5/9\n\nHence, the probability that the flower chosen is pink is 5/9.\n\nSummary:\n\n## There are two bags A and B. A contains 6 red flowers and 3 pink flowers, whereas Bag B contains 2 red flowers and 7 pink flowers. One flower is chosen from a bag randomly. What is the probability that the flower chosen is pink?\n\nThe probability of choosing a pink flower when one flower is chosen randomly from one of the bags is 5/9. This can be calculated by adding the number of pink flowers in both bags and dividing it by the total number of flowers in both bags. It is important to note that the probability of picking a pink flower would be different if the flowers were replaced after being chosen, or if multiple flowers were chosen at once.\n\nRelated Questions:",
null,
"GradeStack Learning Pvt. Ltd.Windsor IT Park, Tower - A, 2nd Floor, Sector 125, Noida, Uttar Pradesh 201303 help@byjusexamprep.com"
] | [
null,
"https://gs-post-images.grdp.co/2018/12/screenshot-2018-12-21-at-3-img1545387500435-75.png-rs-high-webp.png",
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http://ixtrieve.fh-koeln.de/birds/litie/search?q=author_ss%3A%22Kempf%2C+A.O.%22&fq%5B%5D=theme_ss%3A%22Konzeption+und+Anwendung+des+Prinzips+Thesaurus%22 | [
"# Search (3 results, page 1 of 1)\n\n• × `theme_ss:\"Konzeption und Anwendung des Prinzips Thesaurus\"`\n1. Kempf, A.O.: Thesauri und Interoperabilität mit anderen Vokabularen : Die neue Thesaurusnorm ISO 25964 (2013) 8.94\n```8.944634 = weight(author_ss:Kempf, A.O. in 3145) [ClassicSimilarity], result of:\n8.944634 = fieldWeight in 3145, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n8.944634 = idf(docFreq=14, maxDocs=42306)\n1.0 = fieldNorm(doc=3145)\n```\nAuthor\nKempf, A.O.\n2. Kempf, A.O.; Baum, K.: Thesaurus-based indexing of research data in the social sciences : opportunities and difficulties of internationalization efforts (2013) 8.94\n```8.944634 = weight(author_ss:Kempf, A.O. in 3657) [ClassicSimilarity], result of:\n8.944634 = fieldWeight in 3657, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n8.944634 = idf(docFreq=14, maxDocs=42306)\n1.0 = fieldNorm(doc=3657)\n```\nAuthor\nKempf, A.O.\n3. Kempf, A.O.; Neubert, J.: ¬The role of thesauri in an Open Web : a case study of the STW Thesaurus for economics (2016) 8.94\n```8.944634 = weight(author_ss:Kempf, A.O. in 4913) [ClassicSimilarity], result of:\n8.944634 = fieldWeight in 4913, product of:\n1.0 = tf(freq=1.0), with freq of:\n1.0 = termFreq=1.0\n8.944634 = idf(docFreq=14, maxDocs=42306)\n1.0 = fieldNorm(doc=4913)\n```\nAuthor\nKempf, A.O."
] | [
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http://physicsabout.com/first-law-of-thermodynamics/ | [
"Thermodynamics\n\n# First law of thermodynamics:Definition,examples and applications\n\n## 1st law of thermodynamics definition\n\nWhen heat is added to a system there is an increase in the internal energy due to the rise in temperature,an increase in pressure or change in the state.If at the same time,a substance is allowed to do work on its environment by expansion,the heat Q required will be the heat necessary to change the internal energy of the substance from Uin the first state to Uin the second state plus the work W done on the environment.\n\n## 1st law of thermodynamics equation\n\nQ = (U2 –U1) + W\n\nOr\n\nQ = ΔU + W\n\nThus the change in internal energy ΔU =U2 -U1 is defined as Q -W.Since it is the same for all processes concerning the state,the first law of thermodynamics,thus can be stated as:\n\n“In any thermodynamic process,when heat Q is added to a system,this energy appears as an increase in the internal energy ΔU stored in the system plus the work W done by the system on its surroundings.”\n\nA bicycle pump provides a good example.When we pump on the handle rapidly,it becomes hot due to mechanical work done on the gas,rising thereby its internal energy.\n\nHuman metabolism also provides an example of energy conservation.Human beings and other animals do work.When they walk,run,or move heavy objects,work requires energy.Energy is also needed for growth to make new cells and to replace old cells that have died.Energy transforming processes that occur within an organism or named as metabolism.We can apply the first law of thermodynamics:\n\n## 1st law of thermodynamics formula\n\nΔU =Q – W\n\nto an organism of the human body.Work (W) done will result in the decrease in internal energy of the body.Consequently the body temperature or in other words internal energy is maintained by the food we eat.\n\n## What is an example of first law of thermodynamics ?\n\nA bicycle pump provides a good example. when we pump on the handle rapidly, it becomes hot due to mechanical work done on the gas, raising their by its internal energy. one such simple arrangement is shown in figure.\n\nIt consist of a bicycle pump with a blocked outlet allows the air temperature to be monitored. when piston is rapidly pushed, thermometer shows a temperature rise due to increase of internal energy of the air. the push force does work on the air, thereby, increasing its internal energy, which is shown, by the increase in temperature in the air.\n\n## First law of thermodynamics and law of conservation of energy\n\nHuman metabolism also provides an example of energy conservation. human beings and other animals do work when they walk, run, or move heavy objects. work requires energy. energy is also needed for growth to make new cells and to replace old cells that have died. energy transforming processes that occur with in an organisms are named as metabolism. we can apply the first law of thermodynamics as :\n\nΔU = Q-W\n\nto an organism of the human body. work W done will result in the decrease in internal energy of the body. consequently the body temperature or in other words internal energy is maintained by the food we eat.\n\n## Change in internal energy\n\n“A function of thermodynamics coordinates whose final value minus initial value is equal to the value of Q +W in the process is called change in internal energy.”\n\nThe change in internal energy between equilibrium states i and f is given by:\n\nΔEint =Eint,f – Eint,i\n\nΔEint=Q +W\n\nThe value of internal energy Eint,i depends only on the coordinate of the state ‘i’.Similarly,Eint,f depends only on the state of the system and not at all on the path followed.\n\n### Sign convention\n\n• When heat is supplied to the system,it increases the internal energy,so Q is taken as positive(Q > 0)\n• Work done on the system also increases the internal energy ,so it is also taken as positive.(W > 0),In this case first law of thermodynamics is written as:\n\nΔEint=Q +W\n\n• When heat is rejected by the system,it decreases the internal energy,so it is taken as negative.(Q <0)\n• Work done by the system decreases the internal energy ,so it is taken as negative (W <0)\n\nIn this case first law of thermodynamics is written as:\n\nΔEint=Q – W\n\n## Limitations of 1st law of thermodynamics\n\nThe first law of thermodynamics is a general result that is thought to apply to every process in nature which proceeds between equilibrium states.It tells us that energy must be conserved in every process but it does not tell us whether any process that conserves energy can actually occur.\n\n## Applications of 1st law of thermodynamics\n\n• ### Adiabatic process\n\n“A process in which no heat can enter or leave the system is called adiabatic process.”In an adiabatic process ,there is no transfer of heat across the boundary of the system,so Q=0.According to first law of thermodynamics:\n\nΔEint=Q +W\n\nSince\n\nQ = 0 ,SO\n\nΔEint = W\n\nThe work done on the system increases the internal energy.\n\n• ### Isothermal process\n\n“A process in which temperature of the system remains constant is called Isothermal process.”\n\nSince temperature remains constant in isothermal process so the internal energy of the gas must also remain constant so:\n\nΔEint=Q +W\n\n0 = Q + W\n\n⇒ Q =-W\n\n### Constant volume process\n\n“The process in which volume of the system remains constant is known as volume process.”\n\nIf volume of a gas remains constant,the work done will be zero,thus W=0\n\nSo,according to first law of thermodynamics:\n\nΔEint =Q +W\n\nSince W=0,SO\n\n⇒ Q = ΔEint\n\nIn this case all the heat that enters the gas is stored in it as internal energy.\n\n### Cyclic process\n\n“It is a series of processes after which system returns to its initial state.”It is a three step process.It is a cyclic process,because it starts and ends at the same point.\n\nU2=U1\n\nU2-U1=0\n\nΔU=0\n\nFrom the first law of thermodynamics.\n\n### Free expansion\n\n“A process in which a gas goes from one side of the container to the other half initially evacuated is called free expansion.”\n\n## Zeroth law of thermodynamic equation:\n\n“According to this law,when two bodies have equality of temperature with third body,then in turn they have equality of temperature with each other.”\n\n### One Comment\n\n1. asdf says:\n\nfgwdgdvbds\n\nThis site uses Akismet to reduce spam. Learn how your comment data is processed.\n\nClose"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.9337267,"math_prob":0.91181386,"size":6072,"snap":"2019-35-2019-39","text_gpt3_token_len":1378,"char_repetition_ratio":0.19100198,"word_repetition_ratio":0.125239,"special_character_ratio":0.20734519,"punctuation_ratio":0.087029286,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.97585654,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-09-20T16:50:09Z\",\"WARC-Record-ID\":\"<urn:uuid:a7b8e0cf-a48d-46d5-8a25-0be875454906>\",\"Content-Length\":\"94000\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:c275eca3-7e27-41c0-81b0-04a2b63ac26f>\",\"WARC-Concurrent-To\":\"<urn:uuid:e74d9c71-5a96-48f6-81a9-7f643438239a>\",\"WARC-IP-Address\":\"104.27.165.188\",\"WARC-Target-URI\":\"http://physicsabout.com/first-law-of-thermodynamics/\",\"WARC-Payload-Digest\":\"sha1:7TAJSHUUJPDA6U4I74AZZX6TFE5V7J7P\",\"WARC-Block-Digest\":\"sha1:47M5B5PFV2OIFPAQKLXU7NSZOZW5TRZI\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-39/CC-MAIN-2019-39_segments_1568514574050.69_warc_CC-MAIN-20190920155311-20190920181311-00431.warc.gz\"}"} |
https://theteacherscafe.com/teaching-4-nbt-b-5-multiply-a-whole-number-of-up-to-four-digits-by-a-one-digit-number-multiply-two-two-digit-numbers/ | [
"Crush Classroom Boredom by running an escape room at school. Just download, print & play! Show me...\n\n# Teaching 4.NBT.B.5 – Multiply a Whole Number of up to Four Digits by a One-Digit Number & Multiply Two Two-Digit Numbers\n\n##",
null,
"Number & Operations in Base Ten – 4th Grade\n\n#### Use place value understanding and properties of operations to perform multi-digit arithmetic.\n\nCCSS.Math.Content.4.NBT.B.5\nMultiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.\n\nTeacher Notes\nThe teacher needs to understand how place value helps students find the product in multi-digit multiplication problem. It is important to use multi-digit multiplication problems to reenforce place value. Example: “Four tens times three tens is twelve tens. Regroup and put one in the hundreds and two in the tens.”\nStudents who develop flexibility in breaking numbers apart have a better understanding of the importance of place value and the distributive property in multi-digit multiplication.\n\nStudent Knowledge Goals\n\nI know various strategies for multiplication (e.g., partial products, arrays, etc.).\nI know that multiplication is the same as repeated addition.\nI know visual models can be used to show multiplication.\nI understand the properties of multiplication.\nI can interpret and use visual models for multiplication.\nI can explain the strategy I used to solve a multiplication problem.\nI can show my thinking by creating rectangular arrays.\nI can show my thinking by creating area models.\nI can write an equation to a model of a multiplication problem.\n\nVocabulary\narea model\nCommutative Property of Multiplication\nDistributive Property of Multiplication over Addition\nequal groups\nequation\nfactor\nIdentity Property of Multiplication\npartial product\nplace value\nproduct\nrectangular array\nstrategy\n\nLessons\nEngage NY Module 3 B-4 – Interpret and represent patterns when multiplying by 10, 100, and 1,000 in arrays and numerically.\nEngage NY Module 3 B-5 – Multiply multiples of 10, 100, and 1,000 by single digits, recognizing patterns.\nEngage NY Module 3 B-6 – Multiply two-digit multiples of 10 by two-digit multiples of 10 with the area model.\nEngage NY Module 3 C-7 – Multiplication of up to Four Digits by Single-Digit: Use place value disks to represent two-digit by one-digit multiplication.\nEngage NY Module 3 C-8 – Extend the use of place value disks to represent three- and four-digit by one-digit multiplication.\nEngage NY Module 3 C-9 – Multiply three- and four-digit numbers by one-digit numbers applying the standard algorithm.\nEngage NY Module 3 C-10 – Multiply three- and four-digit numbers by one-digit numbers applying the standard algorithm.\nEngage NY Module 3 C-11 – Multiply three- and four-digit numbers by one-digit numbers applying the standard algorithm.\n\nStudent Video Lessons\nLearn Zillion – Multiply Multi-Digit Whole Numbers\nLearn Zillion – Solve multiplication problems\nStudy Jams – Distributive Property\nVirtual Nerd – Multiplication\n\nPrintables\nMultiplication – Single & Multi-Digit\n4.NBT.B.5 – 60 pages of PDF worksheets"
] | [
null,
"https://theteacherscafe.com/wp-content/uploads/2014/08/multiplication-2-300x165.png",
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.76176363,"math_prob":0.97346157,"size":3391,"snap":"2019-51-2020-05","text_gpt3_token_len":741,"char_repetition_ratio":0.2049011,"word_repetition_ratio":0.10412574,"special_character_ratio":0.2025951,"punctuation_ratio":0.08361204,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99747884,"pos_list":[0,1,2],"im_url_duplicate_count":[null,3,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-12-06T10:38:00Z\",\"WARC-Record-ID\":\"<urn:uuid:6a8ab880-0dc4-4925-8fa8-465ac909fe92>\",\"Content-Length\":\"63104\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:0b8637fe-2fd5-4344-a70e-579fc517f900>\",\"WARC-Concurrent-To\":\"<urn:uuid:2cb49f5e-fa56-4269-ab44-1e7bb4ad6023>\",\"WARC-IP-Address\":\"104.18.59.58\",\"WARC-Target-URI\":\"https://theteacherscafe.com/teaching-4-nbt-b-5-multiply-a-whole-number-of-up-to-four-digits-by-a-one-digit-number-multiply-two-two-digit-numbers/\",\"WARC-Payload-Digest\":\"sha1:NZIPJRIXZWZLUIOCNSLAKV3LXYKR2J5C\",\"WARC-Block-Digest\":\"sha1:X3XZTETDG3YTIYTNKYN75K2M4U7QOXFS\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-51/CC-MAIN-2019-51_segments_1575540487789.39_warc_CC-MAIN-20191206095914-20191206123914-00324.warc.gz\"}"} |
https://calculator.name/speed/milehour/metersecond/2.99 | [
"Amount\nFrom\nTo\n\n# 2.99 miles per hour to meters per second\n\nHow many meters per second in 2.99 miles per hour? 2.99 miles per hour is equal to 1.3366496 meters per second.\n\nThis page provides you how to convert between miles per hour and meters per second with conversion factor.\n\n# How to convert 2.99 mi/h to m/s?\n\nTo convert 2.99 mi/h into m/s, follow these steps:\n\nWe know that, 1 m/s = 2.2369362921 mi/h\n\nHence, to convert the value of 2.99 miles per hour into meters per second, divide the speed value 2.99mi/h by 2.2369362921.\n\n2.99 mi/h = 2.99/2.2369362921 = 1.3366496 m/s\n\n### Thus, 2.99 mi/h equals to 1.3366496 m/s\n\nMiles Per Hour Conversion of Miles Per Hour to Meters Per Second\n2.98 mi/h 2.98 mi/h = 1.3321792 m/s\n2.89 mi/h 2.89 mi/h = 1.2919456 m/s\n2.99 mi/h 2.99 mi/h = 1.3366496 m/s\n3.99 mi/h 3.99 mi/h = 1.7836896 m/s"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.6554495,"math_prob":0.9577579,"size":698,"snap":"2022-40-2023-06","text_gpt3_token_len":262,"char_repetition_ratio":0.18299712,"word_repetition_ratio":0.0,"special_character_ratio":0.45845273,"punctuation_ratio":0.17010309,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9977511,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-09-30T02:38:02Z\",\"WARC-Record-ID\":\"<urn:uuid:16d2fdce-827c-428d-8b91-f1f78f09a9d0>\",\"Content-Length\":\"23787\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:91347b66-de69-451a-9d5e-a7a827925dd6>\",\"WARC-Concurrent-To\":\"<urn:uuid:7eb41e38-2319-4638-ab63-1f6a1f2cdbf9>\",\"WARC-IP-Address\":\"3.234.104.255\",\"WARC-Target-URI\":\"https://calculator.name/speed/milehour/metersecond/2.99\",\"WARC-Payload-Digest\":\"sha1:ZIUWL7L6XBQPH6FOQ33EHGEAVMTDS7VV\",\"WARC-Block-Digest\":\"sha1:MDAU3BGP3UL7HH65QW4OX5BN3YQ2FLCV\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-40/CC-MAIN-2022-40_segments_1664030335424.32_warc_CC-MAIN-20220930020521-20220930050521-00532.warc.gz\"}"} |
https://dataorigami.net/blogs/napkin-folding/non-parametric-survival-function-prediction | [
"# Non-parametric survival function prediction\n\nPosted by Cameron Davidson-Pilon on\n\nAs I was developing lifelines, I kept having a feeling that I was gradually moving the library towards prediction tasks. lifelines is great for regression models and fitting survival distributions, but as I was adding more and more flexible parametric models, I realized that I really wanted a model that would predict the survival function — and I didn't care how. This led me to the idea to use a neural net with $$n$$ outputs, one output for each parameter in the cumulative hazard, $$H(t)$$. lifelines has implemented the linear version of this, where each parameter in the cumulative hazard is a linear function of the variables:\n\nLinear:\n\n$$H(t\\;|\\;x) = f(a, b, c) \\\\a = a(x \\cdot \\beta_1^T) \\\\b = b(x \\cdot \\beta_2^T) \\\\c = c(x \\cdot \\mathbf{\\beta}_3^T)$$\n\nNeural Net (NN):\n\n$$H(t\\;|\\;x) = f(a, b, c) \\\\a = \\text{NN}(x)_1 \\\\b = \\text{NN}(x)_2 \\\\c = \\text{NN}(x)_3$$\n\nIf my NN has no hidden layer, it's equivalent to the linear case. Great, so using a NN and a function $$f$$ provides us a good way to predict survival functions. Can we do better? Well, we are stuck with a particular $$f$$, which may or may not be flexible enough to capture all the nuances of possible survival. For example, SaaS churn has very unique survival behavior that a traditional parametric model couldn't capture well.\n\nThinking more about that blog post linked above, I realized that I could use a piecewise approach and split my timescale into partitions as fine as I want, and then predict a constant hazard in each interval. Graphically, something like this:",
null,
"Each output predicts the hazard in a time interval. This piecewise constant hazard can form the cumulative hazard, and then the survival function.\n\nAs the NN increases in depth and complexity, each output benefits from the information in the other time periods. For example, if the model thinks that a certain generated feature is really important, it's exposed for all outputs to use.\n\nWhat about those taus — which I call breakpoints — how are they determined? There are a few options. The first option is the manually specify them. This is okay if we have apriori knowledge of important times, but often we don't. A second option is to expand the neural net to return breakpoints as well. Unfortunately I haven't gotten this model to converge well. The final option considered is to use the dataset to choose breakpoints. In the Kaplan Meier model, the time points of change in the survival function are equal to the unique event times. More generally, the density of the changes in survival is proportional to the density of observed event times. Using this, we can programmatically choose good breakpoints by first creating a density estimate of observed event times, and spacing out breakpoints in proportion to high density. That is, we solve $$p=F_T(t)$$ for $$t$$ at evenly spaced $$p$$ values. Below is an example CDF and how breakpoints are determined:",
null,
"The number of breakpoints is more arbitrary, and can be manually set or heuristically set (like proportional to the square root the number of observed event times).\n\n### Implementation in Python\n\nSo, to recap: we choose breakpoints in proportion to density of event times (which is where the most information is), and use a neural net to determine a subject's hazard in that interval. This is exactly what my new Python library, implements. At the moment, I am building upon the computational library Jax. lifelike's API is similar to Keras, and users familiar with Keras (and Jax) could jump in immediately. The library is also quite opinionated, and based on my own philosophy on survival analysis. For example:\n\n1. The predicted survival function is returned, and no effort is made to compute a point estimate. This aligns with my belief that a distribution has enormous advantages (and on the other side of that coin: point estimates are overrated). Users can compute their own points estimates if they wish\n\n2. Fitting is done against the log-likelihood loss. The survival analysis log-likelihood contains all the information around censoring and observed event times. Is it interpretable? Not really, but most losses are not anyways. The goal is to minimize loss, and I believe the log-likelihood is a terrific loss.\n\nLet's see some inference done with lifelike. The model was trained on an artificial SaaS churn dataset. No prior knowledge about the breakpoints were provided. Below we see the predicted survival function and predicted hazard of a subject.",
null,
"",
null,
"The model was correctly able to find the periods of high SaaS customer churn, and predict the subject's survival function.\n\n### Conclusion\n\nThis NN piecewise-constant model isn't new, and has been published recently in literature before. However, almost all the literature has a very shallow network, and is fit using BFGS. lifelike is the first implementation in a modern computational graph framework, and leaning on Jax means we get autodiff, JIT and GPUs for free. We can scale this model is any dataset size or network we wish (limited only by Jax). For example, my upcoming research could be using images from spectrometers as an input to NNs — lifelike theoretically can handle that.\n\nI hope this blog article inspired you or gave you some new ideas. lifelike is very experimental, and I'm still iterating on APIs and functionality, so use at your own risk. Stay tuned for more updates!"
] | [
null,
"https://cdn.shopify.com/s/files/1/0678/1739/files/download_6_2048x2048.png",
null,
"https://cdn.shopify.com/s/files/1/0678/1739/files/Screen_Shot_2019-08-27_at_7.19.39_PM_grande.png",
null,
"https://cdn.shopify.com/s/files/1/0678/1739/files/Screen_Shot_2019-08-27_at_8.43.47_PM_grande.png",
null,
"https://cdn.shopify.com/s/files/1/0678/1739/files/Screen_Shot_2019-08-27_at_8.43.51_PM_grande.png",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.92688566,"math_prob":0.95554715,"size":5843,"snap":"2022-27-2022-33","text_gpt3_token_len":1291,"char_repetition_ratio":0.111662954,"word_repetition_ratio":0.010405827,"special_character_ratio":0.21598494,"punctuation_ratio":0.10740072,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9785004,"pos_list":[0,1,2,3,4,5,6,7,8],"im_url_duplicate_count":[null,7,null,7,null,7,null,7,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-06-25T00:49:41Z\",\"WARC-Record-ID\":\"<urn:uuid:a0c74553-fe0f-4773-8b9c-9324df434e23>\",\"Content-Length\":\"78713\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:47bc592d-c12e-48bf-86dd-49eb74177731>\",\"WARC-Concurrent-To\":\"<urn:uuid:668bc051-b2a6-49c7-a80c-0ce4d62e9f90>\",\"WARC-IP-Address\":\"23.227.38.32\",\"WARC-Target-URI\":\"https://dataorigami.net/blogs/napkin-folding/non-parametric-survival-function-prediction\",\"WARC-Payload-Digest\":\"sha1:6B7TBJBAHR6H6ZDPGI3RFG3FLCTSFVKN\",\"WARC-Block-Digest\":\"sha1:RB72CFERQU3HAXIBG6Q5BME2TLTYEQ5M\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-27/CC-MAIN-2022-27_segments_1656103033925.2_warc_CC-MAIN-20220625004242-20220625034242-00742.warc.gz\"}"} |
https://stackexchange.com/users/2471992/gabriel-romon | [
"",
null,
"# Gabriel Romon\n\nPiscataway, NJ, USA\n\nInterested in theoretical aspects of Statistics and Machine Learning. Studied at ENSAE Paris and ENS Paris-Saclay, got a master's degree from the latter (MVA).\n\nCurrently a visiting Research Intern at Rutgers University.\n\nA few recent good answers of mine:\n\n$$(X-Y)\\in L^2(P) \\implies X,Y\\in L^1(P)$$\nDCT for convergence in probability\n$$\\frac{S_n}{\\sqrt n}$$ is dense in $$\\mathbb R$$ almost surely\nShowing $$(X_n >c_n \\text{ i.o.})=(\\max_{1\\leq i\\leq n}X_i >c_n \\text{ i.o.})$$\nDerivative of the MGF\nInfinite convex combination of characteristic functions is a characteristic function\nDifferent $$\\mathcal C^\\infty$$ characteristic functions that coincide in a neighborhood of $$0$$\nDifferent metrics that metrize convergence in probability\nRelations between different definitions of the Gaussian width\nWeak consistency from asymptotic unbiasedness\n$$(\\sum_{j=1}^{n} X_{j}) / b_{n} \\overset {P}{\\to} C$$ implies $$b_{n}\\sim b_{n+1}$$\nCLT and pointwise convergence of densities\nIf $$X\\in L^1$$, $$P(X>x)=o\\left(\\frac 1x\\right)$$\nConvex function with directional derivatives in all directions is differentiable\nConcentration of the $$q$$-norm of a Gaussian vector\nAlmost sure convergence of $$\\sum_n \\frac{X_n}n$$\n\nTop Questions\n\n## Polynomials such that roots=coefficients\n\nasked May 11 '14 at 13:33\n\n## Find the liar in the library\n\nasked Apr 28 '15 at 17:30\n\n## Draw a line through all doors\n\nasked Jul 3 '14 at 20:57\n\n## $f^2+(1+f')^2\\leq 1 \\implies f=0$\n\nasked Jun 12 '14 at 18:46\n\n## Reverse Cauchy Schwarz for integrals\n\nasked Jul 27 '14 at 18:47\n\n## Convergence of $\\sum_n \\frac{|\\sin(n^2)|}{n}$\n\nasked Aug 23 '16 at 20:12"
] | [
null,
"https://i.stack.imgur.com/QOCCY.jpg",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7880749,"math_prob":0.99833864,"size":1220,"snap":"2020-45-2020-50","text_gpt3_token_len":348,"char_repetition_ratio":0.10115132,"word_repetition_ratio":0.0,"special_character_ratio":0.25163934,"punctuation_ratio":0.060185187,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9999565,"pos_list":[0,1,2],"im_url_duplicate_count":[null,2,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-12-03T12:10:57Z\",\"WARC-Record-ID\":\"<urn:uuid:42d351fa-2a20-4c31-9f43-f508669eec83>\",\"Content-Length\":\"106366\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:c994191b-5d48-4b10-840f-b94b24d12e07>\",\"WARC-Concurrent-To\":\"<urn:uuid:c516978f-80e8-47a8-bbf0-75b387fdfabb>\",\"WARC-IP-Address\":\"151.101.129.69\",\"WARC-Target-URI\":\"https://stackexchange.com/users/2471992/gabriel-romon\",\"WARC-Payload-Digest\":\"sha1:XMMWFONY46FNRL6LVCGUG637OUTHXDQ7\",\"WARC-Block-Digest\":\"sha1:B7S5OSJ4GRQXYXR4K7BHLGADALEFIHTE\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-50/CC-MAIN-2020-50_segments_1606141727627.70_warc_CC-MAIN-20201203094119-20201203124119-00455.warc.gz\"}"} |
https://answers.everydaycalculation.com/simplify-fraction/7287-4900 | [
"# Answers\n\nSolutions by everydaycalculation.com\n\n## Reduce 7287/4900 to lowest terms\n\nThe simplest form of 7287/4900 is 1041/700.\n\n#### Steps to simplifying fractions\n\n1. Find the GCD (or HCF) of numerator and denominator\nGCD of 7287 and 4900 is 7\n2. Divide both the numerator and denominator by the GCD\n7287 ÷ 7/4900 ÷ 7\n3. Reduced fraction: 1041/700\nTherefore, 7287/4900 simplified to lowest terms is 1041/700.\n\nMathStep (Works offline)",
null,
"Download our mobile app and learn to work with fractions in your own time:\nAndroid and iPhone/ iPad\n\nEquivalent fractions:\n\nMore fractions:\n\n#### Fractions Simplifier\n\n© everydaycalculation.com"
] | [
null,
"https://answers.everydaycalculation.com/mathstep-app-icon.png",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7544063,"math_prob":0.6173606,"size":325,"snap":"2021-04-2021-17","text_gpt3_token_len":95,"char_repetition_ratio":0.14018692,"word_repetition_ratio":0.0,"special_character_ratio":0.36615384,"punctuation_ratio":0.10909091,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9569304,"pos_list":[0,1,2],"im_url_duplicate_count":[null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-04-15T11:53:54Z\",\"WARC-Record-ID\":\"<urn:uuid:ed507d73-59c2-49ad-a9a0-3f4ae001df38>\",\"Content-Length\":\"6075\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:1c054438-ad34-4b93-a1fb-c8f61368e269>\",\"WARC-Concurrent-To\":\"<urn:uuid:1f25fef4-498c-4256-95a8-78753f266acf>\",\"WARC-IP-Address\":\"96.126.107.130\",\"WARC-Target-URI\":\"https://answers.everydaycalculation.com/simplify-fraction/7287-4900\",\"WARC-Payload-Digest\":\"sha1:BS7MNE3B227SLR5QTS7Q4FEGBCTM27PO\",\"WARC-Block-Digest\":\"sha1:Z6CRZ27ECHWVP4RQV2N4TSKXGC74LUWW\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-17/CC-MAIN-2021-17_segments_1618038084765.46_warc_CC-MAIN-20210415095505-20210415125505-00466.warc.gz\"}"} |
https://familyhealthandwealth.info/?post=3608 | [
"# What is the classification of label spread\n\nTraditionally, machine learning technology falls into two categories, one is unsupervised learning and the other is supervised learning.\n\nUnsupervised learning only uses unlabeled example sentences, while supervised learning only uses labeled example sentences for learning.\n\nHowever, in many practical problems, there is only a small amount of tagged data because the cost of tagging data is sometimes high. For example, in biology, structural analysis of a particular protein can be performed. Functional identification can take many years for biologists, but a large amount of unlabeled data is readily available.\n\nThis has led to the rapid development of semi-supervised learning techniques in which labeled and unlabelled samples can be used simultaneously.\n\n### A brief description of the semi-supervised learning theory:\n\nThere are two example sentences for semi-supervised learning, one is labeled and the other is labeled.\n\nLable = {(xi, yi)}, Unlabled = {(xi)}. And in the set L << U.\n\n1. Use labeled samples only, we can generate a supervised classification algorithm\n\n2. Use only unlabelled samples, we can generate an unattended clustering algorithm\n\n3. Use both We hope to be able to add unlabeled samples to 1 to enhance the effect of supervised classification, and we hope to add 2 labeled samples to enhance the effect of unsupervised clustering.\n\nIn general, semi-supervised learning focuses on adding unlabeled samples to the supervised classification algorithm to achieve semi-supervised classification. That is, unmarked samples are added to 1 to improve the classification effect.\n\n### The motivation of semi-supervised learning, motivation\n\nWhen someone is discussing, they always teach us the word motivation. Four or five times in the afternoon it is emphasized that there has to be motivation to write a paper. Let's talk about the motivation of semi-supervised learning.\n\n1. Marked samples are difficult to obtain.\n\nrequires specialized personnel, special equipment, additional costs, etc.\n\n2. Unlabelled samples are relatively cheap.\n\n3. Another point is the bright future of machine learning.\n\n### The difference between semi-supervised learning and direct learning:\n\nThis is also discussed on the internet. The main thing is that semi-supervised learning is inductive and the generated model can be used as a broader sample, while direct learning is only used for classifying the current unlabelled samples.\n\nSimply put, the former uses unlabeled samples to help classify other samples in the future.\n\nThe latter is only used to classify these limited unlabelled samples.\n\nThe following images clearly illustrate the advantages of half monitoring:",
null,
"In the above figure there are only two marked samples, X, O, and the remaining green dots are unmarked samples. With the addition of unlabeled samples, the original classification limit has been shifted 0 to 0.5 It fits better with the actual distribution of the sample.\n\n### Semi-supervised classification of learning algorithms:\n\n1. self-training (self-training algorithm)\n\n2. Generative modelsGenerative model\n\n3. SVMs Semi-monitored support vector machine\n\n4. graph-basedmethodsGraph-based method\n\n5. multiview learingMulti-view algorithm\n\n6. Other methods\n\n### Then briefly introduce the algorithms above\n\nSelf-training algorithm:\n\nstill consists of two example sentences: Labeled = ((xi, yi)); Unlabled = (xj).\n\nexecutes the following algorithm\n\nRepeat:\n\n1. useL creates a classification strategy F;\n\n2. Use F classification U, calculation error\n\n3. Choose the subset u of U, ie the error is small, add the marking. L = L + u;\n\nRepeat the above steps until U is an empty set.\n\nIn the algorithm above, L continuously selects samples with good performance to join U, constantly updates algorithm F of the subset, and finally gets the best F.\n\nA concrete example of self-training: the nearest neighbor algorithm\n\nLet d (x1, x2) be the Euclidean distance between two samples and execute the following algorithm:\n\nRepeat:\n\n1. useL creates a classification strategy F;\n\n2. Choose x = argmin d (x, x0). Select from these x∈U, min x0∈L. So select the unlabelled sample that is closest to the labeled sample.\n\n2. Using F gives x a category F (x).\n\n3. Digits (x, F (x)) are added to L.\n\nRepeat the above steps until U is an empty set.\n\nIn the algorithm above, the \"minimum error\" of self-training is defined by using the Euclidean distance to define the \"best performing unlabeled sample\" and then using F to give a mark, added to L. and also dynamically updated F.\n\nThis algorithm is rendered below:",
null,
"The above figure starts at two points by continuously adding the nearest neighbors and continuously updating F.\n\nThe above algorithm works fine, of course it's rather a poor performance. As follows:",
null,
"Generative model\n\nThe generation algorithm is based on assumptions. For example, let's assume that the original sample conforms to the Gaussian distribution and then use the probability of maximum relief to fit it to a commonly used Gaussian distribution, Gaussian mixture model (GMM).\n\nA brief introduction to the Gaussian mixture model:\n\nAssume the following example distribution:",
null,
"We assume that they correspond to the Gaussian distribution.\n\nThe parameters of the Gaussian distribution are: θ = {w1, w2, µ1, µ2, Σ1, Σ2}\n\nUse the idea of maximum relief to maximize the likelihood of:\n\np (x, y | θ) = p (y | θ) p (x | y, θ).\n\nObtain the following hypothetical distribution:",
null,
"Incidentally, publish an introduction to the Gaussian mixture model protocol:\n\nhttp://blog.csdn.net/zouxy09/article/details/8537620\n\nNext comes our semi-supervised generation algorithm:\n\nThe example distribution is as follows:",
null,
"According to the algorithm, the following distribution is obtained:",
null,
"Compare these two figures to illustrate the difference between the Gaussian mixture model and the semi-supervised generation model:",
null,
"The release functions of these two methods are different. The former maximizes the probability of the occurrence of labeled samples and the latter adds the probability of occurrence of unlabelled samples.\n\nThe specific implementation of the algorithm can be found in the E-M algorithm.\n\nThe algorithm generated this way also has many poor performances:\n\nFor example, suppose the original is distributed as follows:",
null,
"With GMM it will be like this:",
null,
"Some things to consider:\n\n1. Local convergence of the Gaussian mixture\n\n2. Reduce the weight of unlabelled samples\n\nSemi-Supervised SVM, Graph Algorithm Model, Popular Model, etc.\n\nThe theory of SVM is not repeated, it is an optimal hyperplane:\n\nSteal a very impressive SVM picture:",
null,
"This content covers a wide area and a protocol does not fit. If you are interested, you can find out more.\n\n### Finally, the summary is\n\nThe last two pictures:",
null,
"Semi-supervised learning method based on a generative model\n\nThis type of method usually considers the probability that an unlabeled sample belongs to each category as a set of missing parameters and then takes it EM (expectation-maximization) algorithm estimates the maximum probability of the parameters of the generative model. The difference between different methods is that different generative models are selected as base classifiers, for example the Gaussian mixture mixture of experts Naive Bayes (nave Bayes) . Although the semi-supervised learning method is based on a generative model, it is simple, intuitive and can perform better than the discriminatory model when training samples, especially when there are very few labeled samples. However, if the model assumptions do not match the data distribution, a large amount of unlabeled data is used to estimate the model parameters instead of degradation generalization ability . Since finding a suitable generative model for modeling data requires a lot of domain knowledge, the application of semi-supervised learning based on a generative model is limited to practical problems.\n\nSemi-supervised learning method based on a sparse partition\n\nIn this type of procedure, the decision boundary must pass through the sparse data area as far as possible in order to avoid the dense data points in the cluster from being split on both sides of the decision boundary. Based on this idea, Joachim's came up with the TSVM algorithm (As shown2, As shown where the solid line is TSVM, the classification limit and the dashed line do not consider unlabelled data, SVM classification limit). During training, TSVM's algorithm first uses labeled data to train aSVMSestimate the labels of the unlabeled data and then, based on the maximization interval criterion, iteratively swap the labels of the samples on both sides of the classification boundary to maximize the interval, and update the current predictive model accordingly to achieve the correct classification of the labeled data as much as possible. At the same time, “press” the decision limit. Distribute relatively sparse areas over the data. however, TSVM the loss function is not convex, the learning process falls to a local minimum, which affects the generalization ability. To this end, various TSVM, a variant method has been proposed to non-convexThe influence of the loss function on the optimization process, typical methods include deterministic annealing 、 CCCPDirect optimization wait. In addition, the idea of sparse partitioning is also used TSVM design of semi-supervised learning methods other than entropy Regularize semi-supervised learning to enforce the learned classification boundary and avoid data-rich areas 。",
null,
"Number 2 TSVM algorithm diagram \n\nGraph-based semi-supervised learning method\n\nThis type of method uses marked and unmarked data to create a data graph. Based on the adjacency relationship in the diagram, the marking is passed from marked data points to unmarked data points (as shown in the figure). 3 As shown, the light gray and black nodes are marked samples of different categories, and the hollow nodes are unmarked samples. According to the label spreading method, graph-based semi-supervised learning methods can be divided into two categories. One type of method realizes explicit label propagation by defining a label propagation method that meets certain properties, such as: B. the Gaussian random field and harmony transmission of function marks , mark propagation based on global and local consistency Another type of method is the regularity defined in the graphic To give neighbors similar outputs in the diagram, which implicitly passes labels from marked samples to unmarked samples . In fact, the impact of label dissemination methods on learning performance is far less than the impact of data graphing methods on learning performance. When the nature of the data graph deviates from the inherent law of the data, it is difficult to achieve satisfactory learning outcomes regardless of the method used to characterize the spread. However, creating a data graph that reflects the internal relationship of the data often requires a lot of domain knowledge. Fortunately, in some cases, processing can still be done according to the nature of the data to get a more robust data graph. For example, if the data graph does not meet the metric, the non-metric graph can be broken down into multiple metrics charts based on the chart. Mark the spread separately, eliminating non-The negative influence of the metric diagram on the spread of the mark . The graph-based semi-supervised learning method has a good mathematical basis, but because the time complexity of the learning algorithm is mostly O (n3) it is difficult to meet the application requirements of semi-supervised learning for large unlabelled data.",
null,
"Figure 3 Schematic representation of brand expansion\n\nSemi-supervised co-training algorithm\n\nThey assume that the data set has two sufficient and redundant views, i.e. two sets of attributes that meet the following conditions: First, each set of attributes is sufficient to describe the problem, i.e. if the training examples are sufficient, and each set of attributes is sufficient to a strong learner to learn, second, when a label is given, each attribute set is conditionally independent of any other attribute set. During collaborative training, each classifier selects a number of examples with higher labeling certainty (i.e. assigning the correct labeling for example) from the unlabeled examples for identification and adds the flagged examples other A flagged training set of a classifier so that the other participant can update with these newly flagged examples. The collaborative training process is continued iteratively until a certain stop condition is reached.\n\nSuch algorithms implicitly use a clustering hypothesis or a manifold hypothesis. You use two or more learners. During the learning process, these learners select several highly trustworthy ones. The unmarked examples of are marked with each other so that the model can be updated."
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https://math.stackexchange.com/questions/435163/an-exercise-a-property-of-the-fourier-transform-of-wavelet | [
"An exercise. A property of the Fourier transform of wavelet\n\nIn the book \"An Introduction To Wavelet Analysis\" by David F. Walnut, there is,\nExercise 7.45. Show that if $\\psi(x)$ is a wavelet, then $\\sum\\limits_{j}{\\left|\\hat{\\psi}(2^j\\gamma)\\right|^2} = 1$\nHere, $\\psi(x)$ is the mother wavelet function, and $\\hat{\\psi}(\\gamma)$ is the Fourier transform of $\\psi(x)$. $\\hat{\\psi}(\\gamma) = \\int_{-\\infty}^{\\infty}\\psi(x)e^{-2{\\pi}i{\\gamma}x}dx$\nI can not prove it.\nBut testing with Haar Wavelet by Matlab, it seems right.\nCan someone tell me if it's right, and How to prove it?\nAnd thank you for your time!\n\n• Are you sure that's the right question? By orthonormality of the integer translates of $\\psi$, $\\sum_j |\\hat{\\psi}( \\gamma - j)|^2 = 1$ a.e. But that formula you have there looks a little weird to me. – Michael Aug 22 '13 at 1:18\n• Do you need $\\psi$ to be an orthonormal basis? – freak_warrior Feb 4 '14 at 3:39"
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https://forum.allaboutcircuits.com/threads/common-emitter-amplifier-circuit-using-feedback-bi.2197/ | [
"# common emitter amplifier circuit using feedback bi\n\n#### den\n\nJoined Mar 3, 2006\n8\ni don't have the basic of analog, but i tried to look for in the books. unfortunately, the books are using voltage divider biasing instead of feedback biasing. and i can't find it on the net.\n\ni have a circuit like this:",
null,
"would anyone tell me the flow direction of the current in the circuit, and how it makes gain possible?\n\nand, i've tried to calculate the gain, but i think it is wrong.\ni hope someone can help.",
null,
"#### Papabravo\n\nJoined Feb 24, 2006\n14,412\nOriginally posted by den@Mar 3 2006, 11:03 PM\ni don't have the basic of analog, but i tried to look for in the books. unfortunately, the books are using voltage divider biasing instead of feedback biasing. and i can't find it on the net.\n\ni have a circuit like this:",
null,
"would anyone tell me the flow direction of the current in the circuit, and how it makes gain possible?\n\nand, i've tried to calculate the gain, but i think it is wrong.\ni hope someone can help.",
null,
"[post=14616]Quoted post[/post]\nYou said \"On DC, C1 and C2 are short\"\nI think capacitors at DC are OPEN, which allowed you to ignore them for the DC analysis.\n\nYou have not calculated the gain of the circuit, but the DC gain, or beta of the 2N2222 transitor. The value that you calculated is not unreasonable. Always check the data sheet to be sure.\n\nAnother way to get the same result using your equations and your impeccable reasoning, but without all the algebra is:\n\nVc = 5 Volts and Ic = 5V/1K = 5 mA\nVce = 5V\nIb = (5 -0.7)/175K = 24.57 uV\nIc/Ib = 203.488 = beta of 2N2222\n\nNow I have a question for you in return:\n\nOn a set of characteristic curves for the 2N2222, do you now know how to draw the DC load line? If you can do this then you will understand what is happening when your AC signal causes your quiescent point to move along the load line.\n\n#### den\n\nJoined Mar 3, 2006\n8\nim not sure how to draw the DC load line.\n\nim following a Pspice tutorial on displaying the characteristics curve for the transistor 2N2222.\nit says that i can estimate the β for the transistor.\n\nlook at this graph",
null,
"lowest line represents Ib = 0, followed by 10 μ A, 20μ A, and 30μ A.\n\nit is exactly like the graph in the tutorial, but how to estimate the value of β . It is stated in the tutorial that β is approx. 100\n\n#### hgmjr\n\nJoined Jan 28, 2005\n9,029\nHere is the graph you supplied with the load line for the case where the collector supply is 10V and the collector load resistor is 1K.\n\n[attachmentid=1227]\n\nUsing the blue plot on this graph and assuming it corresponds to Ib = 20uamps then I get\n\nRich (BB code):\n 3.5 ma\nBeta = -------- = 175\n0.02 ma\nNot exactly the value obtained by you and papabravo but close.\n\nhgmjr\n\n#### den\n\nJoined Mar 3, 2006\n8\ntq. i have a question.\n\nis 175 DC BETA or AC BETA?\n\n#### hgmjr\n\nJoined Jan 28, 2005\n9,029\nOriginally posted by den@Mar 4 2006, 07:49 AM\ntq. i have a question.\n\nis 175 DC BETA or AC BETA?\n[post=14642]Quoted post[/post]\nThe value for beta I obtained using the load line method would correspond to the DC beta.\n\nhgmjr\n\n#### den\n\nJoined Mar 3, 2006\n8\ntqvm hgmjr. but i would like to ask, how can i obtain the value of AC BETA?\n\nis 325 correct?\n\n#### hgmjr\n\nJoined Jan 28, 2005\n9,029\nOriginally posted by den@Mar 4 2006, 08:45 AM\ntqvm hgmjr. but i would like to ask, how can i obtain the value of AC BETA?\n\nis 325 correct?\n[post=14645]Quoted post[/post]\nI have a question.\n\nIs it possible that what you are interested in calculating is the gain of the transistor stage you have posted?\n\nRich (BB code):\n Vout\nspecifically gain = ----------\nVin\nhgmjr\n\n#### den\n\nJoined Mar 3, 2006\n8\ni'm actually working on a report of something that i never learn before. that's why i'm having so many questions. sorry for that.\n\nit is actually a PSpice simulation project.\ni need your help. from this graph (Gain curve), it means that the Gain, A is 165. am i correct?\n\na bit explaination here, V(in) is the current through the capacitor C1, identified as the input current to the amplifier.\nV1 provide 1V a.c.\n\nwhat else does the graph tell you.",
null,
"and i found from the book saying that gain = Vout/Vin = Vc / Vb\n\nmy other question is, how to obtain Vb.\n\nand Vc = Vce, am i right?\nfrom my calculation, Vce = 5.35V\ntherefore, Vc = 5.35V.\n\ncorrect me if i am wrong.\n\n#### Papabravo\n\nJoined Feb 24, 2006\n14,412\nOriginally posted by hgmjr@Mar 4 2006, 08:22 AM\nHere is the graph you supplied with the load line for the case where the collector supply is 10V and the collector load resistor is 1K.\n\n[attachmentid=1227]\n\nUsing the blue plot on this graph and assuming it corresponds to Ib = 20uamps then I get\n\nRich (BB code):\n 3.5 ma\nBeta = -------- = 175\n0.02 ma\nNot exactly the value obtained by you and papabravo but close.\n\nhgmjr\n[post=14641]Quoted post[/post]\nI think your load line is slightly misplaced. It should intersect the horizontal axis at (10V, 0A) for the transistor in cutoff. It should go through the Q-point at (5V, 5mA) and it should intersect the vertical axis where? Why at (0V, 10mA) when the transistor is in saturation. If you restimate beta with this change I think you should be closer.\n\n#### hgmjr\n\nJoined Jan 28, 2005\n9,029\nWhen speaking of the gain of a transistor it is more appropriate to consider the change in base current due to the change in the input signal voltage.\n\nIn the case of your transistor stage, your input signal change in voltage is developing a current across the 1K resistor in series with the input signal. This change in current is being delivered to the base of the transistor. The transistor is a current gain device whose change in collector current caused by the change in base current is being converted to an output voltage by the collector load resistor.\n\nA rough estimate of the magnitude of your transistor stage midband gain can be obtained by dividing the 175K feedback resistor by the 1K resistance in series with your input signal source to get 175. The actual estimated gain is -175 since the common emitter stage inverts the input signal.\n\nhgmjr\n\n#### hgmjr\n\nJoined Jan 28, 2005\n9,029\nOriginally posted by Papabravo@Mar 4 2006, 11:40 AM\nI think your load line is slightly misplaced. It should intersect the horizontal axis at (10V, 0A) for the transistor in cutoff. It should go through the Q-point at (5V, 5mA) and it should intersect the vertical axis where? Why at (0V, 10mA) when the transistor is in saturation. If you restimate beta with this change I think you should be closer.\n[post=14653]Quoted post[/post]\nI think I have the load line intersecting at 10V, 0A with a slope that is consistent with the 1K resistor in the collector. The y-axis of the graph actually runs from -2.0mA to +6.0mA.\n\nAdded: The load line I drew does pass through the point 5V, 5.0mA as you indicated.\n\nDid I miss something?\n\nhgmjr\n\n#### Papabravo\n\nJoined Feb 24, 2006\n14,412\nOriginally posted by hgmjr@Mar 4 2006, 12:59 PM\nI think I have the load line intersecting at 10V, 0A with a slope that is consistent with the 1K resistor in the collector. The y-axis of the graph actually runs from -2.0mA to +6.0mA.\n\nAdded: The load line I drew does pass through the point 5V, 5.0mA as you indicated.\n\nDid I miss something?\n\nhgmjr\n[post=14655]Quoted post[/post]\nNo, because the 10V label was moved to the left slightly I did not count the ticks correctly and thought that the load line intersected at (10.25V, 0A). I'm sorry for the confusion.\n\n#### den\n\nJoined Mar 3, 2006\n8\nso the gain is 165.\n\ncan you show me the calculation using the conventional way, to get an answer gain = 165? ( or close to that value )\n\nedit : changed the gain value to 165, not 175.\n\n#### hgmjr\n\nJoined Jan 28, 2005\n9,029\nOriginally posted by Papabravo@Mar 4 2006, 12:46 PM\nNo, because the 10V label was moved to the left slightly I did not count the ticks correctly and thought that the load line intersected at (10.25V, 0A). I'm sorry for the confusion.\n[post=14657]Quoted post[/post]\nNo problem. The nature of some attachments can cause confusion. I have more than once misinterpreted a diagram, schematic, or graph.\n\nThanks for the check and balance. The last thing I want to do is mistakenly post a response that is inaccurate or misleading.\n\nhgmjr"
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https://math.stackexchange.com/questions/545417/if-gh-n-is-it-true-that-xn-in-h-for-all-x-in-g/546031 | [
"If $[G:H]=n$, is it true that $x^n\\in H$ for all $x\\in G$?\n\nLet $G$ be a group and $H$ a subgroup with $[G:H]=n$. Is it true that $x^n\\in H$ for all $x\\in G$?\n\nRemarks. The answer is positive whenever $H$ is normal, e.g., for $n=2$. In general, by using the normal core of $H$, one can find an $m\\ge 1$ such that $x^m\\in H$ for all $x\\in G$.\n\n• I am afraid this need not be the case always... – user87543 Oct 30 '13 at 11:03\n• – lhf Apr 3 '14 at 14:32\n\nFor a counterexample, take $S_3$ and the subgroup $H = \\{\\rm{id},(12)\\}$. This has index $3$, but $(13)^3 = (13)\\not\\in H$.\n\n• Funny enough: I've checked for a counterexample taking $G=D_4$ and $Q_8$ (unfortunately these are not useful), but I skipped the simplest non-abelian case! – user89712 Oct 30 '13 at 13:29\n• @user Indeed, $Q_8$ cannot give a counterexample since all subgroups are normal. And $D_4$ cannot since the index of any non-normal subgroup is equal to the exponent of the group. – Tobias Kildetoft Oct 30 '13 at 14:24\n\nTrying to get a whole series of counterexamples, I came up with the following, which shows you how to construct these.\n\nProposition. Let $H$ be a non-trivial subgroup of the finite group $G$, with $n = [G:H]$. Assume that $\\gcd(|H|,n)=1$. Then the following are equivalent.\n\n(a) For all $g \\in G$: $g^n \\in H$.\n(b) $H \\unlhd G$.\n\nProof (b)$\\Rightarrow$(a) is trivial by Lagrange's Theorem. So let us prove (a)$\\Rightarrow$(b) (Sketch) We are going to use induction on $|G|$. To start the induction, we argue that $\\operatorname{core}_G(H) \\neq \\{1\\}$. For suppose $\\operatorname{core}_G(H) =\\{1\\}$ and pick $g\\in G$ and $h\\in H$. By the assumption (a) $(g^{-1}hg)^n=g^{-1}h^ng \\in H$, so $h^n \\in H^{g^{-1}}$. We conclude that $h^n \\in \\operatorname{core}_G(H)$, hence $h^n=1$ and the order of $h$ must divide $n$. But the order also divides $|H|$ and since $\\gcd(|H|,n)=1$, we conclude $h=1$. But $h$ was arbitrary, so $H$ must be trivial, which contradicts the assumption.\n\nIf $H$ is normal there is nothing to prove, so we can safely assume that $\\operatorname{core}_G(H)$ is a proper subgroup of $H$. Now write $\\bar{G}$ for $G/\\operatorname{core}_G(H)$ and $\\bar {H}$ for $H/\\operatorname{core}_G(H)$, then $\\bar {G}$ and $\\bar {H}$ satisfy all the conditions of the proposition. By induction we get $\\bar {H} \\unlhd \\bar {G}$, and this implies $H \\unlhd G$.\n\n• You are welcome! I was inspired by your question! – Nicky Hekster Oct 30 '13 at 21:43\n• I hope you understood that from the Proposition it follows that whenever you have a non-normal Sylow $p$-subgroup $P$ of $G$, the pair $(G,P)$ forms a counterexample. See also Tobias' example! – Nicky Hekster Nov 1 '13 at 13:23\n\nAs the answer given by Tobias shows, this is not true in general. However, it is possible to say some things even when $H$ is not a normal subgroup of $G$.\n\nLet $H \\leq G$ be a subgroup. For all $x \\in G$, there exists $1 \\leq r \\leq [G:H]$ such that $x^r \\in H$.\n\nProof: Let $r \\geq 1$ be the smallest positive integer such that $x^r \\in H$. Then $x, x^2, \\ldots, x^r$ are in distinct cosets of $H$ and thus $r \\leq [G:H]$.\n\n• yes, but this $r$ depends on $x$ unfortunately. – Nicky Hekster Oct 30 '13 at 20:37\n• @NickyHekster: If $H$ is normal, then $r$ is the order of $xH$ in $G/H$. So it is expected that $r$ should depend on $x$. If you want something that is independent of $x$, note that if $[G:H] = n$, then $x^{n!} \\in H$ for all $x \\in G$. This can be seen as a corollary of the above result – Mikko Korhonen Oct 30 '13 at 22:02\n\nHere is series of groups where the property holds, even if the subgroup is not normal.\n\nA subgroup $S$ of a group $G$ is called subnormal (one writes: $S \\lhd \\lhd G$) if there exists a chain of subgroups $H_i$ of $G$, with $S=H_0$, $H_{i-1} \\lhd H_i$, for $i=1, \\dots, r$ and $G=H_r$.\n\nProposition. Let $S \\lhd \\lhd G$ with index$[G:S]=n$. Then for all $g \\in G$ it holds that $g^n \\in G$.\n\nProof Choose subgroups $H_i$ with $S=H_0 \\lhd H_1 \\dots \\lhd H_r=G$, and put index$[H_i:H_{i-1}]=n_i$, $i=1, \\dots , r$. Then $n=n_1 \\dot n_2 \\dots n_r$. If $g \\in G$, since $H_{r-1} \\lhd H_r$, $g^{n_r} \\in H_{r-1}$. Since $H_{r-2} \\lhd H_{r-1}$, $(g^{n_r})^{n_{r-1}}=g^{n_r.n_{r-1}} \\in H_{r-2}$. Now continue this argument till $S$ is reached.$\\square$\n\nSince nilpotent groups are characterized by the fact that all subgroups are subnormal (this can be proved by the “normalizers grow” principle and induction), the proposition allows for a series of examples of a group $G$ and non-normal subgroup $S$, with index$[G:S]=n$, such that $g^n \\in G$ for all $g \\in G$. For example, take $G$ a $p$-group and $S$ any non-normal subgroup. Smallest example: $G=D_4= \\langle a,b:a^4=b^2=1,bab=a^{-1}\\rangle$, with $S=\\{1,b\\}$, which has index 4.\n\n• Thank you again! However, isn't here a better place to post this answer? – user89712 Nov 20 '13 at 21:37\n• Ah, yes thanks, could find it anymore, will put it there too! – Nicky Hekster Nov 20 '13 at 21:47"
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http://www.woodmann.com/forum/archive/index.php/t-6268.html | [
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"PDA\n\nView Full Version : RSA - More than 2 primes\n\njandis\nAugust 20th, 2004, 00:51\nI searched the forums and google but nothing seemed to turn up, except that yes there is a possibility of there being 3-4 primes. Here is the problem:\n\nx = x^d mod n\n\nKnown\n-----\nN = 968b80866737a48f5d6798ae96f16f93f19f, base 16\nD = 1024\n\nWhen trying to use N to find p&q I get 4 prime factors:\n3, 1D, 5AEE72489D, 4DF055177D4679B\n\nSo the problem is p & q are needed in order to find e in the equation e = d^(-1) mod ((p-1)(q-1)). Any help would be appreciated and please excuse my crypto ignorance.\n\nmike\nAugust 20th, 2004, 02:53\nWhat you need to do is compute d^-1 mod (p-1)(q-1)(r-1)(s-1). Which is impossible, since p-1=3-1=2, and 1024 doesn't have an inverse modulo an even number. So your numbers can't be right."
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https://www.molpro.net/manual/doku.php?id=spin-orbit-coupling | [
"# Spin-orbit-coupling\n\nSpin-orbit matrix elements and eigenstates can be computed using either the Breit-Pauli (BP) operator or spin-orbit pseudopotentials (ECPs). The state-interacting method is employed, which means that the spin-orbit eigenstates are obtained by diagonalizing $\\hat H_{el} + \\hat H_{SO}$ in a basis of eigenfunctions of $\\hat H_{el}$. The full Breit-Pauli SO-operator can be used only for MCSCF wavefunctions. For MRCI wavefunctions, the full BP operator is used for computing the matrix elements between internal configurations (no electrons in external orbitals), while for contributions of external configurations a mean-field one-electron fock operator is employed. The error caused by this approximation is usually smaller than 1 cm$^{-1}$.\n\nThe program allows either the computation of individual spin-orbit matrix elements for a given pair of states, or the automatic setting-up and diagonalization of the whole matrix for a given set of electronic states. In the latter case, matrix elements over one-electron operators are also computed and transformed to the spin-orbit eigenstates (by default, the dipole matrix elements are computed; other operators can be specified on the GEXPEC or EXPEC cards, see section One-electron operators and expectation values (GEXPEC)). Since it may be often sufficient to compute the spin-orbit matrix elements in a smaller basis than the energies, it is possible to replace the energy eigenvalues by precomputed values, which are passed to the spin-orbit program by the MOLPRO variable HLSDIAG.\n\nThe one-and two-electron spin-orbit integrals over the BP Hamiltonian can be precomputed and stored on disk using the command\n\nLSINT [,X] [,Y] [,Z] [,ONECENTER] [;TWOINT,twoint;] [;PREFAC,prefac;]\nX, Y, and Z specify the components to be computed. If none of these is given, all three are evaluated. The advantage of precomputing the integrals is that they can then be used in any number of subsequent SO calculations, but this may require a large amount of disk space (note that there are 6 times as many integrals as in an energy calculation). If the LSINT card is not given, the integrals are computed whenever needed. The keyword ONECENTER activates the one-center approximation for one- and two- electron spin-orbit integrals. This can reduce drastically the computing time for large molecules. TWOINT and PREFAC can be used to control the accuracy of spin-orbit integrals. These thresholds are similar to TWOINT and PREFAC for standard integrals. The default value for PREFAC is TWOINT/100, and the default value for TWOINT is $10^{-7}$. In the case when no integrals are precomputed, these thresholds can be specified as options for HLSMAT or TRANLS cards, see below.\n\nThe input for spin-orbit ECPs is described in section effective core potentials. Of course, in ECP-LS calculations the LSINT card is not needed.\n\nIndividual spin-orbit matrix elements can be computed within the MRCI program using\n\nTRANLS,record1.file, record2.file, bra2ms, ket2ms, lsop;\n\nwhere\n\n• record1.file Record holding the bra-wavefunction.\n• record2.file Record holding the ket-wavefunction. Both records must have been generated using the SAVE directive of the MRCI program.\n• bra2ms $2 \\times M_S$ value of the bra-wavefunction.\n• ket2ms $2 \\times M_S$ value of the ket-wavefunction.\n• lsop Cartesian component of the Spin-orbit Hamiltonian.\n\nThis can be one of ${\\tt LSX}$, ${\\tt LSY}$, or ${\\tt LSZ}$ in all electron calculations, and ${\\tt ECPLSX}$, ${\\tt ECPLSY}$, or ${\\tt ECPLSZ}$ in ECP calculations. Starting from the MOLPRO version 2008.1, more types are available which control the approximation level. These are described in section approximations used in calculating spin-orbit integrals and matrix elements.\n\nSince the spin-orbit program is part of the MRCI program, the TRANLS card must be preceded by a [MR]CI card. If in the MRCI step several states of the same symmetry are computed simultaneously using the STATE directive, the matrix elements are computed for all these states. Note that the OCC and CLOSED cards must be the same for all states used in a TRANLS calculation. TRANLS can also be used with records saved by the MULTI program (e.g. multi,cisave=record1.file).\n\nThe selection rules for the $M_S$ values are $\\Delta M_S = \\pm 1$ for the LSX and LSY operators, and $\\Delta M_S=0$ for the LSZ operator. Note that $2M_S$ has to be specified, and so the selection rules applying to the difference of the input values are 0 or 2.\n\nIn all-electron SO calculations the value of the calculated spin-orbit matrix element is saved (in atomic units) in the MOLPRO variables TRLSX, TRLSY and TRLSZ for the $x$, $y$, and $z$ components respectively. For ECP-LS calculations the variables TRECPLSX, TRECPLSY, and TRECPLSZ are used. Note that for imaginary matrix elements (i.e., for the $x$ and $z$ components of the SO Hamiltonian) the matrix elements are imaginary and the stored real values have to be multiplied by $i$. If matrix elements for several states are computed, all values are stored in the respective variable-arrays with the bra-states running fastest.\n\nRecently, more sophisticated approximations were introduced to simplify spin-orbit calculations for larger molecules. These are controlled by specifying the spin-orbit operator type lsop as follows (we omit suffixes X, Y, Z which specify the component):\n\n• LS Standard spin-orbit calculations.\n• ALS The one-center approximation is used for one- and two-electron spin-orbit integrals.\n• FLS The effective Fock-matrix approximation is used for the internal part too.\n• AFLS|AMFI The one-center approximation is used for one- and two-electron spin-orbit integrals, and the effective Fock-matrix approximation for the internal part.\n• ECPLS Effective core potentials are used for all atoms at which they are defined; contributions of all other atoms are neglected (see below).\n\nIn case that the effective Fock matrix is used for all contributions, and no spin-orbit integrals are pre-calculated and stored on disk (i.e., the LSINT command is not given), the Fock matrices are evaluated in direct mode and no integrals are stored on disk. When this is combined with the one-center approximation (AMFI), the computing and I/O times are drastically reduced, and this makes spin-orbit calculations quite fast even for larger molecules.\n\nAlso, the treatment of ECP-type of spin-orbit interaction has been changed and now allows for treating both ECP and non-ECP atoms in one calculation. Thus, in molecules containing both heavy and light atoms, the heavy atoms can be described using ECPs and the light atoms using all-electron basis sets. If the operator type is LS, ALS, FLS, or AFLS, then for the atoms having an ECP spin-orbit operator defined in the basis input the ECP operator is used, while the full BP-operator is used for all other atoms (couplings are neglected). Both one-center and AMFI approximations can be used in this case. If, on the other hand, one specifies the operator type as ECPLS, then the behavior is the same as in the previous versions, i.e., only the ECP contributions are considered and the contributions from all other atoms are neglected.\n\nHLSMAT,type, record1, record2, record3, …\n\nComputes the entire SO matrix and diagonalizes it using all states which are contained in the records record1, record2, record3, …. All records must have been generated using the SAVE directive of the of the MULTI or MRCI programs. type may be either LS for Breit-Pauli calculations, or ECP for ECP-LS calculations. By default, the eigenvalues and dipole transition matrix elements between the ground and excited states are printed.\n\nAs with the TRANLS card, the HLSMAT is recognized only by the MRCI program and must be preceded by a CI card (this is no longer necessary with molpro2021.3 or later). Also, the OCC and CLOSED cards must be the same for all states used in a HLSMAT calculation.\n\nOften it may be sufficient to compute the spin-orbit matrix elements in a smaller basis or at a lower computational level than the energies. It is therefore possible to replace the energy eigenvalues by precomputed values, which are passed to the spin-orbit program by the MOLPRO variable HLSDIAG. The energy values in HLSDIAG must be in exactly the same order as the states in the records given on the HLSMAT card. Before any spin-orbit calculation, the variable HLSDIAG must either be undefined or cleared (then the original energies are used), or must contain exactly the number of energies as the number of states treated in the subsequent spin-orbit calculation (use CLEAR,HLSDIAG to clear any previous values in the variable). It is the user’s responsibility that the order of the energies in HLSDIAG is correct!\n\nSee example in section SO calculation for the S-atom using the BP operator\n\nPRINT,option$_1$=value$_1$, option$_2$=value$_2, \\ldots$\n\nwhere option can be\n\n• HLS HLS=-1 only the SO energies and transition matrix elements between ground and excited states are printed (default).\n\nHLS$\\ge 0$: The SO matrix is printed.\nHLS$\\ge 1$: The property matrices are printed.\nHLS$\\ge 2$: The individual matrix elements are printed (same as OPTION,MATEL).\nHLS$\\ge 3$: Debugging information is printed.\n\n• VLS VLS=-1: No print of eigenvectors (default).\n\nVLS$\\ge 0$: The eigenvectors are printed.\n\nSome options can be set using the OPTION directive (in any order)\n\nOPTIONS [,WIGNER=value] [,HLSTRANS=value] [,MATEL=value]\nwhere\n\n• WIGNER This option determines whether the Wigner-Eckart theorem should be used when the SO matrix is determined. WIGNER=1 (default) uses the theorem, WIGNER=0 calculates each SO matrix element individually. This option is needed for test purposes only.\n• HLSTRANS This option determines whether a SO matrix calculation should be performed in the not spin-symmetry adapted basis set (HLSTRANS=0), in the spin-symmetry adapted basis set (HLSTRANS=1, default) or with both basis sets (HLSTRANS=2). At present, symmetry adaption can only be performed for triplet states, where the following notation is used to indicate the symmetry adapted spin functions: $|S,M_S\\rangle_+ = \\frac{1}{\\sqrt{2}} (|S,M_S\\rangle + |S,-M_S\\rangle)$, $|S,M_S\\rangle_- = \\frac{1}{\\sqrt{2}} (|S,M_S\\rangle - |S,-M_S\\rangle)$. If only singlet and triplet states are considered, the spin-orbit matrix is blocked according to double-group symmetry and the eigenvalues for each each block are printed separately. In all other cases the HLSTRANS option is ignored.\n• MATEL If the entire SO matrix is calculated using HLSMAT, the individual matrix elements are normally not shown. When the option MATEL=1 is given, the individual matrix elements and the contributions of the internal and external configuration classes are printed.\nexamples/s_so.inp\n***,SO calculation for the S-atom\ngeometry={s}\nbasis={spd,s,vtz} !use uncontracted basis\n\n{rhf;occ,3,2,2,,2;wf,16,4,2} !rhf for 3P state\n\n{multi !casscf\nwf,16,4,2;wf,16,6,2;wf,16,7,2; !3P states\nwf,16,1,0;state,3;wf,16,4,0;wf,16,6,0;wf,16,7,0} !1D and 1S states\n\n{ci;wf,16,1,0;save,3010.1;state,3;noexc} !save casscf wavefunctions using mrci\n{ci;wf,16,4,0;save,3040.1;noexc}\n{ci;wf,16,6,0;save,3060.1;noexc}\n{ci;wf,16,7,0;save,3070.1;noexc}\n{ci;wf,16,4,2;save,3042.1;noexc}\n{ci;wf,16,6,2;save,3062.1;noexc}\n{ci;wf,16,7,2;save,3072.1;noexc}\n\n{ci;wf,16,1,0;save,4010.1;state,3} !mrci calculations for 1D, 1S states\ned=energy(1) !save energy for 1D state in variable ed\nes=energy(3) !save energy for 1S state in variable es\n{ci;wf,16,4,2;save,4042.1} !mrci calculations for 3P states\nep=energy !save energy for 3P state in variable ep\n{ci;wf,16,6,2;save,4062.1} !mrci calculations for 3P states\n{ci;wf,16,7,2;save,4072.1} !mrci calculations for 3P states\ntext,only triplet states, casscf\n\nlsint !compute so integrals\n\ntext,3P states, casscf\n{ci;hlsmat,ls,3042.1,3062.1,3072.1} !Only triplet states, casscf\n\ntext,3P states, mrci\n{ci;hlsmat,ls,4042.1,4062.1,4072.1} !Only triplet states, mrci\n\ntext,3P, 1D, 1S states, casscf\n{ci;hlsmat,ls,3010.1,3040.1,3060.1,3070.1,3042.1,3062.1,3072.1} !All states, casscf\n\ntext,only triplet states, use mrci energies and casscf SO-matrix elements\nhlsdiag=[ed,ed,es,ed,ed,ed,ep,ep,ep] !set variable hlsdiag to mrci energies\n{ci;hlsmat,ls,3010.1,3040.1,3060.1,3070.1,3042.1,3062.1,3072.1}\nexamples/i_ecp.inp\n***,I\ngprint,orbitals,civector,basis;\ngthresh,energy=1.d-8,coeff=1.d-8;\ngeometry={I};\n\nbasis={\n!\n! Iodine-ECP (Dirac-Fock) with SO-coupling\n!\necp,I,46,4,3;\n1; 2, 1.00000000, 0.00000000; ! lokal term = 0\n2; 2, 3.50642001, 83.09814545; 2, 1.74736492, 5.06370919; ! s-terme\n4; 2, 2.99860773, 1/3* 81.88444526; 2, 3.01690894, 2/3* 83.41280402; ! p-terms with weights\n2, 1.59415934, 1/3* 2.32392477; 2, 1.19802939, 2/3* 2.72079843;\n4; 2, 1.03813792, 2/5* 6.40131754; 2, 1.01158599, 3/5* 6.21328827; ! d-terms with weights\n2, 2.04193864, 2/5* 19.11604172; 2, 1.99631017, 3/5* 19.08465909;\n4; 2, 2.64971585,-3/7* 24.79106489; 2, 2.75335574,-4/7* 24.98147319; ! f-terms with weights\n2, 0.49970082,-3/7* 0.27936581; 2, 0.79638982,-4/7* 0.70184261;\n4; 2, 2.99860773,-2/3* 81.88444526; 2, 3.01690894, 2/3* 83.41280402; ! ECP-SO for p-terms\n2, 1.59415934,-2/3* 2.32392477; 2, 1.19802939, 2/3* 2.72079843;\n4; 2, 1.03813792,-2/5* 6.40131754; 2, 1.01158599, 2/5* 6.21328827; ! ECP-SO for d-terms\n2, 2.04193864,-2/5* 19.11604172; 2, 1.99631017, 2/5* 19.08465909;\n4; 2, 2.64971585, 2/7* 24.79106489; 2, 2.75335574,-2/7* 24.98147319; ! ECP-SO for f-terms\n2, 0.49970082, 2/7* 0.27936581; 2, 0.79638982,-2/7* 0.70184261;\n!\n! Iodine-basis\n!\ns,I,0.2027624,0.4080619,0.8212297,1.6527350,3.3261500;\nc,1.5,-0.4782372,-0.5811680,0.2617769,0.4444120,-0.1596560;\ns,I,0.05,0.1007509;\np,I,0.2027624,0.4080619,0.8212297,1.6527350,3.3261500;\nc,1.5,0.4251859,0.2995618,0.0303167,-0.2064228,0.0450858;\np,I,0.05,0.1007509,0.01; ! diffuse p-Funktion wegen evt. neg. Part.Ldg\nd,I,0.2,0.4;\nf,I,0.3;\n}\n\n{hf;occ,1,1,1,,1;wf,7,5,1} !scf for 2Pz\n{multi;occ,1,1,1,,1; !casscf with minmal active space\nwf,7,2,1;wf,7,3,1;wf,7,5,1} !average 2P states\n{ci;wf,7,2,1;noexc;save,5000.2} !save casscf vector for 2Px state\n{ci;wf,7,3,1;noexc;save,5100.2} !save casscf vector for 2Py state\n{ci;wf,7,5,1;noexc;save,5200.2} !save casscf vector for 2Pz state\n{ci;wf,7,2,1;save,6000.2} !mrci for 2Px state\n{ci;wf,7,3,1;save,6100.2} !mrci for 2Py state\n{ci;wf,7,5,1;save,6200.2} !mrci for 2Pz state\n\n{multi;occ,1,2,2,,2 !casscf with larger active space\nwf,7,2,1;wf,7,3,1;wf,7,5,1} !average 2P states\n{ci;wf,7,2,1;noexc;save,5010.2}\n{ci;wf,7,3,1;noexc;save,5110.2}\n{ci;wf,7,5,1;noexc;save,5210.2}\n{ci;wf,7,2,1;save,6010.2}\n{ci;wf,7,3,1;save,6110.2}\n{ci;wf,7,5,1;save,6210.2}\n\ntext,casscf, occ,1,1,1,,1\n{ci;hlsmat,ecp,5000.2,5100.2,5200.2} !do spin-orbit calculations\ntext,casscf, occ,1,2,2,,2\n{ci;hlsmat,ecp,5010.2,5110.2,5210.2}\n\ntext,mrci, occ,1,1,1,,1\n{ci;hlsmat,ecp,6000.2,6100.2,6200.2}\ntext,mrci, occ,1,2,2,,2\n{ci;hlsmat,ecp,6010.2,6110.2,6210.2}\nexamples/i_ecp_cpp.inp\n***,I\n\ngprint,orbitals,civector,basis;\ngthresh,energy=1.d-8,coeff=1.d-8;\ngeometry={I};\n\nbasis={\n!\n! Iodine-ECP (Dirac-Fock) with SO-coupling and cpp\n!\necp,I,46,4,3;\n1; 2, 1.00000000, 0.00000000; ! lokal term = 0\n2; 2, 3.50642001, 83.09814545; 2, 1.74736492, 5.06370919; ! s-terme\n4; 2, 2.99860773, 1/3* 81.88444526; 2, 3.01690894, 2/3* 83.41280402; ! p-terms with weights\n2, 1.59415934, 1/3* 2.32392477; 2, 1.19802939, 2/3* 2.72079843;\n4; 2, 1.03813792, 2/5* 6.40131754; 2, 1.01158599, 3/5* 6.21328827; ! d-terms with weights\n2, 2.04193864, 2/5* 19.11604172; 2, 1.99631017, 3/5* 19.08465909;\n4; 2, 2.64971585,-3/7* 24.79106489; 2, 2.75335574,-4/7* 24.98147319; ! f-terms with weights\n2, 0.49970082,-3/7* 0.27936581; 2, 0.79638982,-4/7* 0.70184261;\n4; 2, 2.99860773,-2/3* 81.88444526; 2, 3.01690894, 2/3* 83.41280402; ! ECP-SO for p-terms\n2, 1.59415934,-2/3* 2.32392477; 2, 1.19802939, 2/3* 2.72079843;\n4; 2, 1.03813792,-2/5* 6.40131754; 2, 1.01158599, 2/5* 6.21328827; ! ECP-SO for d-terms\n2, 2.04193864,-2/5* 19.11604172; 2, 1.99631017, 2/5* 19.08465909;\n4; 2, 2.64971585, 2/7* 24.79106489; 2, 2.75335574,-2/7* 24.98147319; ! ECP-SO for f-terms\n2, 0.49970082, 2/7* 0.27936581; 2, 0.79638982,-2/7* 0.70184261;\n!\n! Iodine-basis\n!\ns,I,0.2027624,0.4080619,0.8212297,1.6527350,3.3261500;\nc,1.5,-0.4782372,-0.5811680,0.2617769,0.4444120,-0.1596560;\ns,I,0.05,0.1007509;\np,I,0.2027624,0.4080619,0.8212297,1.6527350,3.3261500;\nc,1.5,0.4251859,0.2995618,0.0303167,-0.2064228,0.0450858;\np,I,0.05,0.1007509,0.01; ! diffuse p-Funktion wegen evt. neg. Part.Ldg\nd,I,0.2,0.4;\nf,I,0.3;\n}\n\n{cpp,init,1; ! core polarization potential\nI,2,1.028,,,1.23} ! Iod-Atom,form of cut-off function, static polarizability\n! 1.23 = exponential-factor of cut-off function\n\n{hf;occ,1,1,1,,1;wf,7,5,1} !scf for 2Pz\n{multi;occ,1,1,1,,1; !casscf with minmal active space\nwf,7,2,1;wf,7,3,1;wf,7,5,1} !average 2P states\n{ci;wf,7,2,1;noexc;save,5000.2} !save casscf vector for 2Px state\n{ci;wf,7,3,1;noexc;save,5100.2} !save casscf vector for 2Py state\n{ci;wf,7,5,1;noexc;save,5200.2} !save casscf vector for 2Pz state\n{ci;wf,7,2,1;save,6000.2} !mrci for 2Px state\n{ci;wf,7,3,1;save,6100.2} !mrci for 2Py state\n{ci;wf,7,5,1;save,6200.2} !mrci for 2Pz state\n\n{multi;occ,1,2,2,,2 !casscf with larger active space\nwf,7,2,1;wf,7,3,1;wf,7,5,1} !average 2P states\n{ci;wf,7,2,1;noexc;save,5010.2}\n{ci;wf,7,3,1;noexc;save,5110.2}\n{ci;wf,7,5,1;noexc;save,5210.2}\n{ci;wf,7,2,1;save,6010.2}\n{ci;wf,7,3,1;save,6110.2}\n{ci;wf,7,5,1;save,6210.2}\n\ntext,casscf, occ,1,1,1,,1\n{ci;hlsmat,ecp,5000.2,5100.2,5200.2} !do spin-orbit calculations\ntext,casscf, occ,1,2,2,,2\n{ci;hlsmat,ecp,5010.2,5110.2,5210.2}\n\ntext,mrci, occ,1,1,1,,1\n{ci;hlsmat,ecp,6000.2,6100.2,6200.2}\ntext,mrci, occ,1,2,2,,2\n{ci;hlsmat,ecp,6010.2,6110.2,6210.2}"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.75692654,"math_prob":0.9920478,"size":18019,"snap":"2023-40-2023-50","text_gpt3_token_len":6489,"char_repetition_ratio":0.1385512,"word_repetition_ratio":0.24936494,"special_character_ratio":0.37388313,"punctuation_ratio":0.2868526,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9679342,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-10-04T10:49:12Z\",\"WARC-Record-ID\":\"<urn:uuid:6b574137-a082-4425-bb3d-b31425f07034>\",\"Content-Length\":\"45318\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:bd27b993-8a33-46de-a0ab-2bd44bf75981>\",\"WARC-Concurrent-To\":\"<urn:uuid:a926ce89-77eb-40ab-85a8-d7588da47904>\",\"WARC-IP-Address\":\"129.69.55.20\",\"WARC-Target-URI\":\"https://www.molpro.net/manual/doku.php?id=spin-orbit-coupling\",\"WARC-Payload-Digest\":\"sha1:IWOBTQTXPMCBG2SN2KW7QQXFHKPUYF7V\",\"WARC-Block-Digest\":\"sha1:GKA6JT4QCMROPQCR5ICCMTTCNGADYAW6\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-40/CC-MAIN-2023-40_segments_1695233511364.23_warc_CC-MAIN-20231004084230-20231004114230-00242.warc.gz\"}"} |
https://www.colorhexa.com/dcf848 | [
"# #dcf848 Color Information\n\nIn a RGB color space, hex #dcf848 is composed of 86.3% red, 97.3% green and 28.2% blue. Whereas in a CMYK color space, it is composed of 11.3% cyan, 0% magenta, 71% yellow and 2.7% black. It has a hue angle of 69.5 degrees, a saturation of 92.6% and a lightness of 62.7%. #dcf848 color hex could be obtained by blending #ffff90 with #b9f100. Closest websafe color is: #ccff33.\n\n• R 86\n• G 97\n• B 28\nRGB color chart\n• C 11\n• M 0\n• Y 71\n• K 3\nCMYK color chart\n\n#dcf848 color description : Bright yellow.\n\n# #dcf848 Color Conversion\n\nThe hexadecimal color #dcf848 has RGB values of R:220, G:248, B:72 and CMYK values of C:0.11, M:0, Y:0.71, K:0.03. Its decimal value is 14481480.\n\nHex triplet RGB Decimal dcf848 `#dcf848` 220, 248, 72 `rgb(220,248,72)` 86.3, 97.3, 28.2 `rgb(86.3%,97.3%,28.2%)` 11, 0, 71, 3 69.5°, 92.6, 62.7 `hsl(69.5,92.6%,62.7%)` 69.5°, 71, 97.3 ccff33 `#ccff33`\nCIE-LAB 92.935, -30.727, 76.586 64.252, 82.818, 18.731 0.388, 0.5, 82.818 92.935, 82.52, 111.861 92.935, -11.165, 94.999 91.005, -33.232, 51.5 11011100, 11111000, 01001000\n\n# Color Schemes with #dcf848\n\n• #dcf848\n``#dcf848` `rgb(220,248,72)``\n• #6448f8\n``#6448f8` `rgb(100,72,248)``\nComplementary Color\n• #f8bc48\n``#f8bc48` `rgb(248,188,72)``\n• #dcf848\n``#dcf848` `rgb(220,248,72)``\n• #84f848\n``#84f848` `rgb(132,248,72)``\nAnalogous Color\n• #bc48f8\n``#bc48f8` `rgb(188,72,248)``\n• #dcf848\n``#dcf848` `rgb(220,248,72)``\n• #4884f8\n``#4884f8` `rgb(72,132,248)``\nSplit Complementary Color\n• #f848dc\n``#f848dc` `rgb(248,72,220)``\n• #dcf848\n``#dcf848` `rgb(220,248,72)``\n• #48dcf8\n``#48dcf8` `rgb(72,220,248)``\n• #f86448\n``#f86448` `rgb(248,100,72)``\n• #dcf848\n``#dcf848` `rgb(220,248,72)``\n• #48dcf8\n``#48dcf8` `rgb(72,220,248)``\n• #6448f8\n``#6448f8` `rgb(100,72,248)``\n• #c7eb09\n``#c7eb09` `rgb(199,235,9)``\n• #d3f617\n``#d3f617` `rgb(211,246,23)``\n• #d7f72f\n``#d7f72f` `rgb(215,247,47)``\n• #dcf848\n``#dcf848` `rgb(220,248,72)``\n• #e1f961\n``#e1f961` `rgb(225,249,97)``\n• #e5fa79\n``#e5fa79` `rgb(229,250,121)``\n• #eafb92\n``#eafb92` `rgb(234,251,146)``\nMonochromatic Color\n\n# Alternatives to #dcf848\n\nBelow, you can see some colors close to #dcf848. Having a set of related colors can be useful if you need an inspirational alternative to your original color choice.\n\n• #f8e848\n``#f8e848` `rgb(248,232,72)``\n• #f8f748\n``#f8f748` `rgb(248,247,72)``\n• #ebf848\n``#ebf848` `rgb(235,248,72)``\n• #dcf848\n``#dcf848` `rgb(220,248,72)``\n• #cdf848\n``#cdf848` `rgb(205,248,72)``\n• #bff848\n``#bff848` `rgb(191,248,72)``\n• #b0f848\n``#b0f848` `rgb(176,248,72)``\nSimilar Colors\n\n# #dcf848 Preview\n\nThis text has a font color of #dcf848.\n\n``<span style=\"color:#dcf848;\">Text here</span>``\n#dcf848 background color\n\nThis paragraph has a background color of #dcf848.\n\n``<p style=\"background-color:#dcf848;\">Content here</p>``\n#dcf848 border color\n\nThis element has a border color of #dcf848.\n\n``<div style=\"border:1px solid #dcf848;\">Content here</div>``\nCSS codes\n``.text {color:#dcf848;}``\n``.background {background-color:#dcf848;}``\n``.border {border:1px solid #dcf848;}``\n\n# Shades and Tints of #dcf848\n\nA shade is achieved by adding black to any pure hue, while a tint is created by mixing white to any pure color. In this example, #050600 is the darkest color, while #fdfff2 is the lightest one.\n\n• #050600\n``#050600` `rgb(5,6,0)``\n• #151901\n``#151901` `rgb(21,25,1)``\n• #252c02\n``#252c02` `rgb(37,44,2)``\n• #353f02\n``#353f02` `rgb(53,63,2)``\n• #455103\n``#455103` `rgb(69,81,3)``\n• #556404\n``#556404` `rgb(85,100,4)``\n• #657705\n``#657705` `rgb(101,119,5)``\n• #758a05\n``#758a05` `rgb(117,138,5)``\n• #859d06\n``#859d06` `rgb(133,157,6)``\n• #95b007\n``#95b007` `rgb(149,176,7)``\n• #a5c307\n``#a5c307` `rgb(165,195,7)``\n• #b5d608\n``#b5d608` `rgb(181,214,8)``\n• #c5e909\n``#c5e909` `rgb(197,233,9)``\n• #d1f60f\n``#d1f60f` `rgb(209,246,15)``\n• #d5f722\n``#d5f722` `rgb(213,247,34)``\n• #d8f735\n``#d8f735` `rgb(216,247,53)``\n• #dcf848\n``#dcf848` `rgb(220,248,72)``\n• #e0f95b\n``#e0f95b` `rgb(224,249,91)``\n• #e3f96e\n``#e3f96e` `rgb(227,249,110)``\n• #e7fa81\n``#e7fa81` `rgb(231,250,129)``\n• #eafb94\n``#eafb94` `rgb(234,251,148)``\n• #eefca6\n``#eefca6` `rgb(238,252,166)``\n• #f2fcb9\n``#f2fcb9` `rgb(242,252,185)``\n• #f5fdcc\n``#f5fdcc` `rgb(245,253,204)``\n• #f9fedf\n``#f9fedf` `rgb(249,254,223)``\n• #fdfff2\n``#fdfff2` `rgb(253,255,242)``\nTint Color Variation\n\n# Tones of #dcf848\n\nA tone is produced by adding gray to any pure hue. In this case, #a0a0a0 is the less saturated color, while #dcf848 is the most saturated one.\n\n• #a0a0a0\n``#a0a0a0` `rgb(160,160,160)``\n• #a5a898\n``#a5a898` `rgb(165,168,152)``\n• #aaaf91\n``#aaaf91` `rgb(170,175,145)``\n• #afb68a\n``#afb68a` `rgb(175,182,138)``\n• #b4be82\n``#b4be82` `rgb(180,190,130)``\n• #b9c57b\n``#b9c57b` `rgb(185,197,123)``\n• #becc74\n``#becc74` `rgb(190,204,116)``\n• #c3d36d\n``#c3d36d` `rgb(195,211,109)``\n• #c8db65\n``#c8db65` `rgb(200,219,101)``\n• #cde25e\n``#cde25e` `rgb(205,226,94)``\n• #d2e957\n``#d2e957` `rgb(210,233,87)``\n• #d7f14f\n``#d7f14f` `rgb(215,241,79)``\n• #dcf848\n``#dcf848` `rgb(220,248,72)``\nTone Color Variation\n\n# Color Blindness Simulator\n\nBelow, you can see how #dcf848 is perceived by people affected by a color vision deficiency. This can be useful if you need to ensure your color combinations are accessible to color-blind users.\n\nMonochromacy\n• Achromatopsia 0.005% of the population\n• Atypical Achromatopsia 0.001% of the population\nDichromacy\n• Protanopia 1% of men\n• Deuteranopia 1% of men\n• Tritanopia 0.001% of the population\nTrichromacy\n• Protanomaly 1% of men, 0.01% of women\n• Deuteranomaly 6% of men, 0.4% of women\n• Tritanomaly 0.01% of the population"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.5240207,"math_prob":0.6073236,"size":3701,"snap":"2020-24-2020-29","text_gpt3_token_len":1630,"char_repetition_ratio":0.12604815,"word_repetition_ratio":0.011111111,"special_character_ratio":0.5403945,"punctuation_ratio":0.23692992,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9785179,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-05-30T09:17:10Z\",\"WARC-Record-ID\":\"<urn:uuid:9f6a7b96-eacb-486f-b9ed-9a460f102c4d>\",\"Content-Length\":\"36307\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:c4a260ff-5b6f-4368-b3f8-2080e454ad98>\",\"WARC-Concurrent-To\":\"<urn:uuid:db3344e8-e284-461b-b544-8422be078934>\",\"WARC-IP-Address\":\"178.32.117.56\",\"WARC-Target-URI\":\"https://www.colorhexa.com/dcf848\",\"WARC-Payload-Digest\":\"sha1:4ESFRDVU24CGDVHHKDVB22W4RTEUESMX\",\"WARC-Block-Digest\":\"sha1:CFRFFKXDJFKJWWPNZHXHAVG6CKFS3FDA\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-24/CC-MAIN-2020-24_segments_1590347407667.28_warc_CC-MAIN-20200530071741-20200530101741-00279.warc.gz\"}"} |
https://calculatorall.com/lcm-calculator | [
"# LCM Calculator - Calculatorall.com\n\nLCM or Least Common Multiple of 2 numbers (or more) is a concept in mathematics that refers to smallest positive number that can be divided by both. There are different methods that can be used for calculating the LCM of given numbers. However, the simplest option you have is to avoid details and rely on our LCM calculator.\n\nNevertheless, here are the methods that are used for the calculation of LCM.\n\n Please provide numbers separated by comma to calculate. 330,75,450,225\n\nBrute Force Method\n\nBrute Force method for the calculation of least common multiple is amongst most basic options that one can try to find the LCM of the given numbers. However, it can quickly become quite tedious.\n\nPrime Factorization Method\n\nPrime Factorization is arguably the one of the most systematic ways of finding LCM of given numbers. It simply works by breaking down the numbers into the product of their prime numbers. After that the LCM is determined by multiplying highest power of all the prime numbers. Keep in mind, however, that even though it's more efficient way of computing LCM than the method mentioned above but it is still limited only to the smaller numbers.",
null,
"Greatest Common Divisor Method\n\nThis is another viable option for finding LCM of given numbers. Also known as Greatest Common Factor, it is used for finding LCM by dividing product of the numbers by the GCF. In case of more than two numbers, you first have to find LCM of first two numbers and then find LCM of the resultant with the third number. The final result will be the LCM of three numbers.\n\nAlso keep in mind that it's not important which numbers are used first in calculating the LCM and the only thing you have to ensure is to use all the numbers in the process.\n\nDepending on when you are using these methods for finding LCM, they all have their own merits and it's up to the user as to which method they want to use.\n\nHow LCM Calculator Works?\n\nComing back to our LCM calculator, you don't really have to get into the trouble of what's going on at the back end. The calculator just requires you to enter the numbers whose LCM ha to be found all separated by commas and shows you the result as soon as you click on the calculate button.\n\nAs mentioned earlier, this LCM calculator also has its own restrictions and may not work accurately with very large numbers. But you can still use it confidently with the smaller numbers."
] | [
null,
"https://calculatorall.com/images/lcm-calculator.jpg",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.96922743,"math_prob":0.9754553,"size":2294,"snap":"2020-34-2020-40","text_gpt3_token_len":478,"char_repetition_ratio":0.1537118,"word_repetition_ratio":0.004914005,"special_character_ratio":0.19572799,"punctuation_ratio":0.069977425,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.96008265,"pos_list":[0,1,2],"im_url_duplicate_count":[null,3,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-08-12T18:28:33Z\",\"WARC-Record-ID\":\"<urn:uuid:702ec580-8938-410f-b10c-032c502fd894>\",\"Content-Length\":\"14258\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:5434676a-322a-483a-8cd9-d6f85693e429>\",\"WARC-Concurrent-To\":\"<urn:uuid:0f2029b8-8910-478b-81ff-29f7539a9220>\",\"WARC-IP-Address\":\"63.250.38.7\",\"WARC-Target-URI\":\"https://calculatorall.com/lcm-calculator\",\"WARC-Payload-Digest\":\"sha1:2WCATJHNJR5MIBUW4DTZXVNJW6T5A2QI\",\"WARC-Block-Digest\":\"sha1:TEH4VVMMUSIHX6WWIZQXZU4BFPGMM4K5\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-34/CC-MAIN-2020-34_segments_1596439738913.60_warc_CC-MAIN-20200812171125-20200812201125-00054.warc.gz\"}"} |
https://dralexheard.com/judith-heard-and-husband-alex-heard-uganda.html | [
"# Math pattern solver\n\nIn this blog post, we discuss how Math pattern solver can help students learn Algebra. Our website can solving math problem.\n\n## The Best Math pattern solver",
null,
"Here, we debate how Math pattern solver can help students learn Algebra. The app, called Mathway, allows users to enter a problem and then see step-by-step instructions for solving it. In addition, the app includes a wide range of features that make it easy to use, including a built-in calculator and a library of solved problems. As a result, Mathway is an essential tool for any student who wants to improve their math skills.\n\nA calculus solver can be a helpful tool for these students. By enterinng the equation they are trying to solve, the solver will provide step-by-step instructions on how to solve it. This can be a valuable resource for students who are struggling to understand the material or simply need extra practice. With the help of a calculus solver, students can improve their grades and get a better understanding of the subject.\n\nFactor calculators are a great tool for anyone who wants to quickly figure out the factors of a number. Although there are various ways to calculate factors, a factor calculator can be especially helpful if you're working with large numbers or if you need to find all of the factors of a number. Generally, you simply enter the number that you want to factor into the calculator and then hit the \"calculate\" button. The calculator will then display all of the factors of that number. In addition, some factor calculators will also show you any prime factors that may be present. Factor calculators can be found online or in some math textbooks.\n\nWeb math is a website that provides a variety of resources for students who are struggling with math. The site includes a wide range of topics, from basic arithmetic to more advanced concepts like calculus. In addition, the site provides interactive tools that help students visualize and understand complex concepts. Web math also offers a forum where students can ask questions and get help from other users. The site is free to use, and it does not require registration.\n\nCollege algebra word problems can be difficult to solve, but there are some tips that can help. First, read the problem carefully and make sure you understand what is being asked. Next, identify the key information and identify any variables that need to be solved for. Once you have all of the information, you can start solving the problem. College algebra word problems often require the use of equations, so it is important to be familiar with the various types of equations and how to solve them. With a little practice, solving college algebra word problems can become easier.\n\n## We cover all types of math issues",
null,
"the app has saved me numerous times during my math difficulties. Whether it be helping with homework or studying for a test, the app always gives me the explanation I need to get to the answer. Answers come fast and accurately. 10/10 app, would highly recommend.\n\nWelcome Ward",
null,
"Honestly this huge functionality than wolfram. I installed both for comparing. At last, I choose this because life time payment. Thank you This app is helpful when you're in a jam late at night, especially if you don't have a tutor sleeping over at your house.\n\nHailie Ward\n\nHow do you solve math problems Generic rectangle solver 2 equation solver How to solve a problem with two variables Solution problems algebra"
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null,
"https://dralexheard.com/PSY6320a40ff2880/author-profile.jpg",
null,
"https://dralexheard.com/PSY6320a40ff2880/testimonial-one.jpg",
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"https://dralexheard.com/PSY6320a40ff2880/testimonial-two.jpg",
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https://faculty.math.illinois.edu/Macaulay2/doc/Macaulay2-1.21/share/doc/Macaulay2/TensorComplexes/html/_map_lp__Labeled__Module_cm__Labeled__Module_cm__Z__Z_rp.html | [
"# map(LabeledModule,LabeledModule,ZZ) -- creates scalar multiplication by an integer as a LabeledModuleMap\n\n## Description\n\nThis function produces essentially the same output as map(Module,Module,ZZ), except that the output map belongs to the class LabeledModuleMap, and thus remembers the labeled module structure of the source and target. If $m=0$ then the output is the zero map. If $m\\ne 0$, then $F$ and $G$ must have the same rank.\n\n i1 : S=QQ[x,y,z]; i2 : F=labeledModule(S^3); o2 : free S-module with labeled basis i3 : G=labeledModule(S^2); o3 : free S-module with labeled basis i4 : g=map(F,G,0) o4 = 0 3 2 o4 : Matrix S <--- S i5 : h=map(F,F,1) o5 = | 1 0 0 | | 0 1 0 | | 0 0 1 | 3 3 o5 : Matrix S <--- S"
] | [
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https://solvedlib.com/show-that-u1-u2-u3-v1-v2-v3-u1v1-u202-u3v3-is-not,253081 | [
"# Show that ((U1, U2, U3), (V1, V2, V3)) = U1v1 – U202 – U3V3 is not...\n\n###### Question:",
null,
"Show that ((U1, U2, U3), (V1, V2, V3)) = U1v1 – U202 – U3V3 is not an inner product on R3.\n\n#### Similar Solved Questions\n\n##### Three point charges Ql=-IOC. Q2=-IOC and Q3-+40C are line shown in the sketch [00 m;aanged alongWhat is the electric field point P? What the electric potentab polnt P?\nThree point charges Ql=-IOC. Q2=-IOC and Q3-+40C are line shown in the sketch [00 m; aanged along What is the electric field point P? What the electric potentab polnt P?...\n##### Find the exact value of x. 19\nFind the exact value of x. 19...\n##### Journal Cash dividends involve three events. On the date of declaration, the directors bind the company...\njournal Cash dividends involve three events. On the date of declaration, the directors bind the company to pay the dividend. A dividend declaration reduces retained earnings and creates a current liability. On the date of record, recipients of the dividend are identified. On the date of payment,...\n##### On April 6. Home Furnishings purchased $45,000 of merchandise from Una's Imports, terms 1/10, 1/45. On... On April 6. Home Furnishings purchased$45,000 of merchandise from Una's Imports, terms 1/10, 1/45. On April 8, Home Furnishings returned $9,500 of the merchandise to Una's Imports for credit. Home Furnishings paid cash for the merchandise on April 15 Required a. What is the amount that Home... 1 answer ##### Help please 2009 Q1 (70 points). Consider an economy composed of just three firms producing three... Help please 2009 Q1 (70 points). Consider an economy composed of just three firms producing three goods. Suppose that quantities of output produced and prices in 2009 and 2010 are as the followings: 2010 Quantity Price Quantity Price Cars 10$2,000 | 12 $3,000 Computers 4$1,000 $500 Oranges 1000... 1 answer ##### QUESTION 32 The genetic code was deciphered in part by experiments in which synthetic polynucleotides were... QUESTION 32 The genetic code was deciphered in part by experiments in which synthetic polynucleotides were used as mRNAs to direct protein synthesis in cell-free extracts (in-vitro system). In the test tube, artificial conditions were used that allowed ribosomes to start protein synthesis anywhere o... 5 answers ##### The following graph is for lake during what season? Temp (C)28SurfaceDepthBottom A SpringB. SummerC FallD: Winter The following graph is for lake during what season? Temp (C) 28 Surface Depth Bottom A Spring B. Summer C Fall D: Winter... 1 answer ##### Indicate whether the pair of structures shown represent stereoisomers, constitutional isomers, different conformations of the same... Indicate whether the pair of structures shown represent stereoisomers, constitutional isomers, different conformations of the same compound, or the same conformation of a compound viewed from a different perspective. Note that cis, trans isomers are an example of stereoisomers. H2CH3 CH2CH3 CH2CH3 ... 5 answers ##### In a club can be chosen that with 8 male and 11 female members, how many 5-member committees = haveall men? c(v,s)-s6rm Ilwb) 3 men and women?(s,3) = (13)=at least one women? In a club can be chosen that with 8 male and 11 female members, how many 5-member committees = have all men? c(v,s)-s6 rm Ilw b) 3 men and women? (s,3) = (13)= at least one women?... 5 answers ##### 20 points) For the slope ficld above sketch the solution (HTve through the given point.A. (-2,0)C. (4,1)(0,1) 20 points) For the slope ficld above sketch the solution (HTve through the given point. A. (-2,0) C. (4,1) (0,1)... 1 answer ##### 1) Identify the functional group (alkane, alkene, ketone, aldehyde, aldehyde, etc) for the compounds providing the... 1) Identify the functional group (alkane, alkene, ketone, aldehyde, aldehyde, etc) for the compounds providing the IR spectra: % Transmittance 4000 3500 3000 1500 1000 500 2500 2000 Wavenumber(cm) % Transmittance 4000 3500 3000 1500 1000 500 2500 2000 Wavenumber(cm) % Transmittance 1000 3500 3000 15... 1 answer ##### Problem-5 (20 pts): Consider the DC servo motor shown in Figure-5. Assume that the input of the s... Problem-5 (20 pts): Consider the DC servo motor shown in Figure-5. Assume that the input of the system is the applied armature voltage ea and the output is the load shaft position θ2. Assume also the following numerical values for the components: Ra-) Armature winding resistance = 0.2Ω L... 1 answer ##### Identify the equation as separable, linear, exact, or having an integrating factor that is a function... Identify the equation as separable, linear, exact, or having an integrating factor that is a function of either x or y alone. (4x+3x - 3y)dx + (xy3 – x-2)dy = 0 Select all that apply. A. exact B. has an integrating factor u(x) or (y) not equal to a constant C. linear D. separable E. none of th... 5 answers ##### .A planet orbits its sun with a mean distance of 228 millionkilometers. That distance differs by 21 million kilometers attimes. What are the maximum (aphelion) and minimum (perihelion)distances between the planet and its sun? .A planet orbits its sun with a mean distance of 228 million kilometers. That distance differs by 21 million kilometers at times. What are the maximum (aphelion) and minimum (perihelion) distances between the planet and its sun?... 1 answer ##### Section A: (Circle or bubble the correct answer with PEN) Which solution of a base contains... Section A: (Circle or bubble the correct answer with PEN) Which solution of a base contains the smallest number of moles of a base? a) 5.0 L of 4.0 M b) 0.50 L of 4.0 M c) 4.0 L of 0.40 M d) 0.50 L of 0.40 M What is the volume of 0.1220 M HNO3 solution required to completely neutralize 17.50 mL of 0... 1 answer ##### . Consider the following model for pastry folding: A piece of pastry is folded in thirds back over itself and then... . Consider the following model for pastry folding: A piece of pastry is folded in thirds back over itself and then stretched to the original length as illustrated in this diagram This folding and stretching can be modeled by the function f(z) = 2-3r if 1/3 <2/3 with the graph shown below. The dia... 5 answers ##### Volume of NaOH vs pH12d3312312 412.5025 -6512.712.712.742.812.812.86 1291 12941eena Volume of NaOH vs pH 12d3312312 412.5025 -6512.712.712.742.812.812.86 1291 1294 1 eena... 1 answer ##### 4) xy\" + y' – xy = 0,x, = 0 a) What are the points of... 4) xy\" + y' – xy = 0,x, = 0 a) What are the points of singularity for each specific problem? b) Does this ODE hold a general power series solution at the specific xO? Justify your answer, if your answer is yes, the proceed as follows: Compute the radius of analyticity and report the co... 5 answers ##### Not yet answeredMarked out of 1.00Flag questionFind the 8Oth percentile for the following data:50 30 45025 22526 30Select one:a. 26b. 30C. 45d. does not exist Not yet answered Marked out of 1.00 Flag question Find the 8Oth percentile for the following data: 50 30 45 0 25 225 26 30 Select one: a. 26 b. 30 C. 45 d. does not exist... 5 answers ##### Which mutant meiosis has @ crossing over event? Explain your selection: Explain what is abnormal about BOTH of the mutant meiosis pathways shown Why do you think the first mutant meiotic division (0sd1) generated seeds that were NOT sterile (still able to form living plants when germinated)?iii) Which mutant meiosis has @ crossing over event? Explain your selection: Explain what is abnormal about BOTH of the mutant meiosis pathways shown Why do you think the first mutant meiotic division (0sd1) generated seeds that were NOT sterile (still able to form living plants when germinated)? iii)... 4 answers ##### In patients with metastatic prostate cancer the standard first - line treatment is hormonal therapy; which blocks androgenic signals that promote tumor growth and progression. Several anti-androgens have been approved and they are well tolerated: However; many patients will eventually develop resistance to these drugs, and their disease will progress even when androgenic signals are completely blocked: Assuming there are no other available therapies, what type of new drug should be developed to In patients with metastatic prostate cancer the standard first - line treatment is hormonal therapy; which blocks androgenic signals that promote tumor growth and progression. Several anti-androgens have been approved and they are well tolerated: However; many patients will eventually develop resist... 4 answers ##### The transpose of a column vector is a row vector with the sare entries:vT = [v1 U2vn]Define ej € Rn to be the vector of all zeros with the exception of a one in the jth entry_Suppose that i < j and k < €. Show that ife;e]ee?i8 not zero then i < €. The transpose of a column vector is a row vector with the sare entries: vT = [v1 U2 vn] Define ej € Rn to be the vector of all zeros with the exception of a one in the jth entry_ Suppose that i < j and k < €. Show that if e;e]ee? i8 not zero then i < €.... 5 answers ##### Question 6Evaluate the integral: (Enter your answer using function notation use In(x) instead of In K 2 + 6r + 13 dxSubmit QuestionQuestion 7Determine whether the integral is convergent or divergent: 22 61 dx 9 + 26convergent divergentevaluate it. If the quantity diverges, enter \"DNE\" Ifit is convergent, Question 6 Evaluate the integral: (Enter your answer using function notation use In(x) instead of In K 2 + 6r + 13 dx Submit Question Question 7 Determine whether the integral is convergent or divergent: 22 61 dx 9 + 26 convergent divergent evaluate it. If the quantity diverges, enter \"DNE\"... 5 answers ##### Reaction 1: CuO(s)→Cu(s)+12O2(g)ΔG°=155kJ/molrxnA chemist wants to produce Cu(s) from a sample ofpure CuO(s) according to reaction 1, represented by theequation above.(a) Using the data in the following table, calculate the valueof the standard entropy change, ΔS°, for thereaction.SubstanceAbsolute Entropy at298 K (JK−1mol−1)Cu(s)33O2(g)205CuO(s)43(b) Given that ΔG° for reaction 1 ispositive (155kJ/molrxn), what must be true about thesign of ΔH° for the reaction? Justify your Reaction 1: CuO(s)→Cu(s)+12O2(g)ΔG°=155kJ/molrxn A chemist wants to produce Cu(s) from a sample of pure CuO(s) according to reaction 1, represented by the equation above. (a) Using the data in the following table, calculate the value of the standard entropy change, ΔS°, for t... 1 answer ##### Exercise 18.47 The solubility of Mg(OH), in a particular buffer solution is 0.61 B/L Part A... Exercise 18.47 The solubility of Mg(OH), in a particular buffer solution is 0.61 B/L Part A What must be the pH of the butter solution? Express your answer using two decimal places. O ? %0AXO pH - 12.32 Submit Previous Awe t Aswer X Incorrect; Try Again; Sattempts remaining Provide Feedback... 5 answers ##### A* \"PVzr-[ do(m)dc (2? si(n)dm 2(hnz) a* \"P Vzr-[ do (m) dc (2? si (n) dm 2(hnz)... 5 answers ##### Point) Given the graph ofy = f(r) below; answer all of the folloiing questions(a) List the intervals where f is increasing: (b) List the intervals where f is decreasing: (c) List the distinct y-values of the local maximums any exist: (d) List the distinct y-values of the local minimums, if any exist: e) Find the y-value of the maximum, if it exists:Find the y-value the minimum; if it exists: point) Given the graph ofy = f(r) below; answer all of the folloiing questions (a) List the intervals where f is increasing: (b) List the intervals where f is decreasing: (c) List the distinct y-values of the local maximums any exist: (d) List the distinct y-values of the local minimums, if any exis... 5 answers ##### 2 1 8 W 2 5 8 4 01 jWh 1 2 1 [ } 1 F 1 8 0 [ 3 1 M 0 L 4 8 2 f J[ 9 M V 1 0 N 5 3 { 1 5 1 8 9 1 J 1 1 8 2 1 7 { 2 1 8 W 2 5 8 4 01 jWh 1 2 1 [ } 1 F 1 8 0 [ 3 1 M 0 L 4 8 2 f J[ 9 M V 1 0 N 5 3 { 1 5 1 8 9 1 J 1 1 8 2 1 7 {... 5 answers ##### Ensidu_Pield Q &nJ 1_exkesi fielJE-BIe Pcone HhtE = Q(z) isclosed ensidu_Pield Q &nJ 1_exkesi fielJE-BIe Pcone HhtE = Q(z) isclosed... 1 answer ##### ASAP ble 3 20 Pts. A transfer function Bode p ots are shown below. Answer the... ASAP ble 3 20 Pts. A transfer function Bode p ots are shown below. Answer the following questions; please eatly draw the appropriate lines as needed, show your work and write your answers in the provided table a. What is the gain margin in dB? b. What is the phase margin in degrees? c. What is t... 1 answer ##### Can you please show me clear steps to A, B and C QUESTION 8: A manufacturing... can you please show me clear steps to A, B and C QUESTION 8: A manufacturing process produces semiconductor chips with a known failure rate 6.3%. Assume that chip failures are independent of one another and follow a normal distribution, and you will be producing 2000 chips tomorrow: A. Find the expe... 1 answer ##### Home Depot Advertise Don't Advertise$300,000 S50,000 $100,000$100,000 Advertise Lowes $200,000$200,000 $50,000$300,000 Don't...\nHome Depot Advertise Don't Advertise $300,000 S50,000$100,000 $100,000 Advertise Lowes$200,000 $200,000$50,000 \\$300,000 Don't Advertise Matrix 1 Refer to Matrix 1 for questions 13 to 15. 13. In the matrix above, A. Lowes has a dominant strategy, but Home Depot does not B. Home Depot has a...\n##### Selva thae problems Adun cut bbrk ol woodasshawn What u the volume 0 the block alwood?cubk@ Two prisms ate shovn bdlowWtuch Stements about the volume} 0l thEn ChocieAI thtJpot Bumhod {1t0ut LeIa !hat Fet LJilthAn Ltoni Dyedge LT4ura Fr-ng Aw\" Eulsm n ireniod tr 'reclnguls ptnmLntui\nSelva thae problems Adun cut bbrk ol woodasshawn What u the volume 0 the block alwood? cubk @ Two prisms ate shovn bdlow Wtuch Stements about the volume} 0l thEn ChocieAI thtJpot Bumhod {1t0ut LeIa !hat Fet LJilthAn Ltoni Dyedge LT4ura Fr-ng Aw\" Eulsm n ireniod tr 'reclnguls ptnm Lntui..."
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https://calcforme.com/percentage-calculator/162-is-183-percent-of-what | [
"# 162 is 183 Percent of what?\n\n## 162 is 183 Percent of 88.52\n\n%\n\n162 is 183% of 88.52\n\nCalculation steps:\n\n162 ÷ ( 183 ÷ 100 ) = 88.52\n\n### Calculate 162 is 183 Percent of what?\n\n• F\n\nFormula\n\n162 ÷ ( 183 ÷ 100 )\n\n• 1\n\nPercent to decimal\n\n183 ÷ 100 = 1.83\n\n• 2\n\n162 ÷ 1.83 = 88.52 So 162 is 183% of 88.52\n\nExample"
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https://www.gradesaver.com/textbooks/math/algebra/college-algebra-11th-edition/chapter-1-section-1-8-absolute-value-equations-and-inequalities-1-8-exercises-page-154/58 | [
"## College Algebra (11th Edition)\n\n$\\bf{\\text{Solution Outline:}}$ Use the concepts of absolute value expressions to solve the given inequality, $|18-3x|\\lt-13 .$ $\\bf{\\text{Solution Details:}}$ The absolute value of a number is the distance of the number from $0,$ and hence, is always a nonnegative number. For any $x$, the given absolute value expression at the left side is always a nonnegative number. This will never be $\\text{ less than }$ the negative expression at the right. Hence, there is $\\text{ no solution .}$"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.77855253,"math_prob":0.99981636,"size":527,"snap":"2020-45-2020-50","text_gpt3_token_len":131,"char_repetition_ratio":0.1376673,"word_repetition_ratio":0.024691358,"special_character_ratio":0.2637571,"punctuation_ratio":0.12,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99885654,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-10-24T00:56:06Z\",\"WARC-Record-ID\":\"<urn:uuid:15600b0a-3ad3-499c-a171-773543f569a4>\",\"Content-Length\":\"81799\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:69b36a27-b706-4021-b0ce-8624adfb1859>\",\"WARC-Concurrent-To\":\"<urn:uuid:9ec75dfa-89dd-49bb-8f0f-eb86a26431bd>\",\"WARC-IP-Address\":\"18.213.227.210\",\"WARC-Target-URI\":\"https://www.gradesaver.com/textbooks/math/algebra/college-algebra-11th-edition/chapter-1-section-1-8-absolute-value-equations-and-inequalities-1-8-exercises-page-154/58\",\"WARC-Payload-Digest\":\"sha1:KUT7TRBFG6F2QEV3XVOXHFJE36CW5D5W\",\"WARC-Block-Digest\":\"sha1:33MA4HLGUOEJH2OCWOE2Z3Q2VDACVHRW\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-45/CC-MAIN-2020-45_segments_1603107881551.11_warc_CC-MAIN-20201023234043-20201024024043-00396.warc.gz\"}"} |
https://www.daniweb.com/programming/software-development/threads/310851/c-string-vector-of-vectors-and-conversion-of-string-to-char | [
"Hi,\n\nI am kind of new to C++ and really stuck with a problem. Here I am trying to parse a string and after comparing to a pre-declared array save the tokens in a vector of vectors. It is giving a number of errors and I'm not sure what to change since I am using char* tokens in a another function as well. Could someone please tell me what is the best way to go about doing this and what changes i should make. Here is the function that is giving errors.\n\n``````void parse(std::vector<char*>* tokens)\n{\nstd::vector<string> entity;\n\nint i=0, j=0, row=0;\nbool ent=false;\n\n//Initialisation of the program relationship model\nentity = \"stmt\";\nentity = \"assign\";\nentity = \"while\";\nentity = \"if\";\nentity = \"constant\";\nentity = \"prog_line\";\nentity = \"call\";\n\nvector< vector<string> > matrix;\n\n/*for(int i=0; i<7; i++){\nmatrix.push_back(vector <string>());\nmatrix[i].push_back(\"xyz\");\n}\n\ncout << matrix; */\n\n//compare the tokens to the array entity\nfor(i=0; i<tokens.size(); i++)\n{\nfor(j=0; j<7; j++)\n{\nmatrix.push_back(vector <string>());\nif(tokens[i] == entity[j])\ndo{\ni++;\nif(tokens[i] != \",\" || tokens[i] != \";\")\nmatrix[row][j] = tokens[i];\n}while(tokens[i] != \";\");\n}\n}\n}``````\n\n## Recommended Answers\n\nYou have declared tokens as a pointer to a vector:\n\n``std::vector<char*>* tokens``\n\nBut are then trying to access the size() function as if it is an object (with the '.' operator):\n\n``tokens.size()``\n\nYou need to instead use the -> operator:\n\n``tokens->size()``\n\nYour program is also inconcistent in the way it declares std namespace. If you don't use `using namespact std;` or `using std::vector;` then you have to preface every instance of vector with std::, such as `std::vector< std::vector< std::string> > something;` As for the parameter tokens -- unless that is an …\n\nYour program will get a runtime error because vector entity doesn't have any elements, so all those assignments in lines 9-15 will fail.\n\n>>if(strcmp((*tokens), ',')\n\nIf you only want to compare two single characters to see if they are the same then why use strcmp()?? Just use == …\n\n## All 9 Replies\n\nYou have declared tokens as a pointer to a vector:\n\n``std::vector<char*>* tokens``\n\nBut are then trying to access the size() function as if it is an object (with the '.' operator):\n\n``tokens.size()``\n\nYou need to instead use the -> operator:\n\n``tokens->size()``\n\nYou also have to use\n\n``(*tokens)[i]``\n\ninstead of\n\n``tokens[i]``\n\nDavid\n\ncommented: thnks a ton... :) +0\n\nYour program is also inconcistent in the way it declares std namespace. If you don't use `using namespact std;` or `using std::vector;` then you have to preface every instance of vector with std::, such as `std::vector< std::vector< std::string> > something;` As for the parameter tokens -- unless that is an array of std::vector objects, then it would be better to dealred it as a reference instead of a pointer -- `std::vector<std::string>& tokens)` . That would remove the ambiguity between passing a reference to a single vector object or passing an array of vector objects. Declaring it as a pointer we don't know which one you meant without seeing the function that calld it.\n\nHey,\nI have made the changes suggested and yet get a few errors, albeit fewer.\nerror C2664: 'strcmp' : cannot convert parameter 2 from 'char' to 'const char *'\nI am not sure how to debug this.\n\nMy updated code is as follows:\n\n``````void parse(std::vector<char*>* tokens)\n{\nstd::vector<char*> entity;\n\nint i=0, j=0, row=0;\nchar* temp = new char;\n\n//Initialisation of the program relationship model\nentity = \"stmt\";\nentity = \"assign\";\nentity = \"while\";\nentity = \"if\";\nentity = \"constant\";\nentity = \"prog_line\";\nentity = \"call\";\n\nstd::vector<std::vector<char*>> matrix;\n/*for(int i=0; i<7; i++){\nmatrix.push_back(vector <string>());\nmatrix[i].push_back(\"xyz\");\n}\n\ncout << matrix; */\n\n//compare the tokens to the array entity\nfor(i=0; i<tokens->size(); i++)\n{\nfor(j=0; j<7; j++)\n{\nmatrix.push_back(vector <char*>());\nif(strcmp((*tokens)[i], entity[j])==0)\ndo{\ni++;\nif(strcmp((*tokens)[i], ',')==0 || strcmp(tokens[i],';')==0)\nstrcpy(temp, (*tokens)[i]);\n}while(strcmp((*tokens[i]), ';')==0);\n}\n}\n}``````\n\nHelp is greatly appreciated. I am not really clear about the declaration of tokens. If needed I could post that function as well.\n\nI don't know how to compare char arrays, I've never tried :)\n\n``std::vector<std::string>``\n\nYour program will get a runtime error because vector entity doesn't have any elements, so all those assignments in lines 9-15 will fail.\n\n>>if(strcmp((*tokens), ',')\n\nIf you only want to compare two single characters to see if they are the same then why use strcmp()?? Just use == operator to compare them\n\n``````for(i=0; i<tokens->size(); i++)\n{\nfor(j=0; j<7; j++)\n{\nmatrix.push_back(vector <char*>());\nif(strcmp((*tokens)[i], entity[j])==0)\ndo{\ni++;\nif( *tokens->at(i) == ',' || *tokens->at(i) == ';')\nstrcpy(temp, tokens->at(i));\n}while(*tokens->at(i) == ';');\n}\n}``````\ncommented: you're awesome!!! +0\n\nYes, I realised I should've used push_back.\nI have one last question. How can i copy the temp value to matrix?\n\nWould this work?\n\n``matrix[j].push_back(temp)``\n\nYou've been a great help!! Thanks a ton. :)\n\nI know C++ a little but I have been out of touch and I realised my concepts have become effy. Could you please recommend a good way to get a grasp over it? Any good books or sight?\n\nUpdated code:\nOn running this prints garbage values. :S\n\n``````void parse(std::vector<char*>* tokens)\n{\nvector<char*> entity;\n\nint i=0, j=0, row=0;\nchar* temp = new char;\n\n//Initialisation of the program relationship model\nentity.push_back(\"stmt\");\nentity.push_back(\"assign\");\nentity.push_back(\"while\");\nentity.push_back(\"if\");\nentity.push_back(\"constant\");\nentity.push_back(\"prog_line\");\nentity.push_back(\"call\");\n\nstd::vector<std::vector<char*>> matrix;\n//compare the tokens to the array entity\nfor(i=0; i<tokens->size(); i++)\n{\nfor(j=0; j<7; j++)\n{\nmatrix.push_back(vector <char*>());\nif(strcmp((*tokens)[i], entity[j])==0)\ndo{\ni++;\nif( *tokens->at(i) == ',' || *tokens->at(i) == ';')\nstrcpy(temp, tokens->at(i));\nmatrix[j].push_back(temp);\n}while(*tokens->at(i) == ';');\n}\n}\n\nfor(i=0; i<7; i++)\nfor(j=0; j<matrix[i].size(); j++)\ncout << matrix[i][j] << endl;\n\n}``````\n\nI have checked to print tokens. And it has correct values.\n\nBe a part of the DaniWeb community\n\nWe're a friendly, industry-focused community of 1.20 million developers, IT pros, digital marketers, and technology enthusiasts learning and sharing knowledge."
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7275763,"math_prob":0.9334086,"size":1180,"snap":"2021-04-2021-17","text_gpt3_token_len":334,"char_repetition_ratio":0.1462585,"word_repetition_ratio":0.0,"special_character_ratio":0.34491524,"punctuation_ratio":0.18181819,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9904393,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-04-10T19:26:12Z\",\"WARC-Record-ID\":\"<urn:uuid:96754b60-f182-4933-b7cb-e079378be35b>\",\"Content-Length\":\"101009\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:53b79964-4a9b-4df2-b404-e630456e3b54>\",\"WARC-Concurrent-To\":\"<urn:uuid:b840b063-7c15-425f-81e7-aba4baaa1145>\",\"WARC-IP-Address\":\"104.22.5.5\",\"WARC-Target-URI\":\"https://www.daniweb.com/programming/software-development/threads/310851/c-string-vector-of-vectors-and-conversion-of-string-to-char\",\"WARC-Payload-Digest\":\"sha1:RCG5TUMN7BU6HGW3ZSC3PNWLVGFW57BO\",\"WARC-Block-Digest\":\"sha1:OOQ6P7XHH47C62B65NNTHD2VV2PZSP2X\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-17/CC-MAIN-2021-17_segments_1618038057476.6_warc_CC-MAIN-20210410181215-20210410211215-00018.warc.gz\"}"} |
https://hypertextbook.com/facts/2005/LoadingABike.shtml | [
"An educational, fair use website\n\n## Introduction\n\nThis is a mechanics problem that a physics student should be able to solve.\n\nIn the clip \"Loading a Bike\", a man rides his motorcycle off a 45° ramp into a white van.\n\nThe following can be determined when analyzing the clip:\n\n1. Maximum Height\n2. Take Off Speed\n3. Horizontal Distance\n\n## 1. Maximum Height\n\nFind the hang time by counting the frames from when the motorcycle leaves the ramp until it enters the van using Windows Media Player Classic. The frame rate can be found by locating it at the bottom of Windows Media Player Classic.\n\nhang time = 57 frames\nframe rate = 25 frames per second\n\nTo calculate the hang time in seconds, divide the hang time by the frame rate.\n\ntime = (hang time)/(frame rate)\ntime = (57 frames)/(25 frames per second)\ntime = 2.28 seconds\n\nNow assuming that the incline is 45° and the take off and landing are the same height, the maximum height can be found. Since we are calculating the maximum height, the time is halved.\n\ns = yo + vot + ½&nsp;at2\nymax = 0 m + (0 m/s) t + ½&nsp;at2\nymax = ½&nsp;at2\nymax = ½&nsp;(9.81 m/s2)(1.14 s)2\nymax = 6.37 m\n\n## 2. Take Off Speed\n\n• To find the take off speed, the vertical and horizontal speeds must first be found. First calculate the vertical speed:\n\nvy2 = vo2 + 2as\nvy2 = (0 m/s)2 + 2aymax\nvy2 = 2aymax\nvy = (2aymax)½&nsp;\nvy = (2(9.81 m/s2)(6.37 m))½&nsp;\nvy = 11.18 m/s\n\n• Since we know/ have assumed the incline to be 45°, trigonometry can be used to find the horizontal speed and the takeoff speed.\n\ntan 45° = vy/vx\nvx = vy/tan 45°\nvx = (11.18 m/s)/(1) = 11.18 m/s\n\n• Now that we have horizontal and vertical velocity components the Pythagorean theorem can be used to solve for takeoff speed.\n\nc2 = a2 + b2\nv2 = vx2 + vy2\nv = (vx2 + vy2)½\nv = ((11.18 m/s)2 + (11.18 m/s)2)½\nv = 15.81 m/s at 45°\n\n## 3. Horizontal Distance\n\n• Vertical and horizontal acceleration and velocities are independent of each other.\n• Using the horizontal speed calculated in the previous part, the horizontal distance can be found.\n\ns = vxt\ns = (11.18 m/s)(2.28 s)\ns = 25.49 m\n\nManuel Caban -- 2005\n\nPhysics on Film\n1. Feature Films\n2. One Reelers\n3. Short Video Clips"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7547282,"math_prob":0.995671,"size":2708,"snap":"2020-24-2020-29","text_gpt3_token_len":822,"char_repetition_ratio":0.12684911,"word_repetition_ratio":0.015686275,"special_character_ratio":0.31462333,"punctuation_ratio":0.10471204,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99818695,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-06-04T08:16:23Z\",\"WARC-Record-ID\":\"<urn:uuid:0dac1071-9c0c-467f-9528-ba44307156b9>\",\"Content-Length\":\"26644\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:5410b698-19fb-44b7-84a9-36c104a7dfa3>\",\"WARC-Concurrent-To\":\"<urn:uuid:17e632df-0846-49fb-9ece-0e8a347758c3>\",\"WARC-IP-Address\":\"172.96.187.211\",\"WARC-Target-URI\":\"https://hypertextbook.com/facts/2005/LoadingABike.shtml\",\"WARC-Payload-Digest\":\"sha1:APZQVDW2TQPKBUF6AUTI47HG2PUFF6DY\",\"WARC-Block-Digest\":\"sha1:DIQES25WGJVWFOHKMCOQELG4WO46KJQ6\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-24/CC-MAIN-2020-24_segments_1590347439213.69_warc_CC-MAIN-20200604063532-20200604093532-00424.warc.gz\"}"} |
https://mathsdoctor.co.uk/revision-help/gcse/number/arithmetic-with-fractions/ | [
"# Arithmetic with Fractions\n\n## Topic Overview\n\nFor your GCSE maths exam, you will need to add, subtract, multiple, divide, simplify and convert fractions. This guide will introduce you to the basic principles of fractions as well as providing several worked examples of how to answer examination questions.\n\nA fraction is defined as the part of a whole. Within a fraction you have two values; the numerator and the denominator.\n\nThe numerator is the top number of the fraction, which tells you how many parts of a whole you have.\n\nThe denominator is the bottom number, which tells you how many parts the whole is divided into.\n\nFor example, when looking at the fraction:\n\n1/2\n\n1 is the numerator and 2 is the denominator.\n\n## Key Concepts\n\nIn the new linear GCSE Maths paper, you will be required to recognise certain properties of fractions and solve related calculations. According to the Edexcel Revision Checklist for the linear GCSE Maths paper, you will be required to:\n\n• Multiply and divide fractions\n• Understand equivalent fractions\n• Simplify a fraction by cancelling all common factors\n• Recognise that each terminating decimal is a fraction\n• Recognise that recurring decimals are exact fractions and that some exact fractions are recurring decimals\n• Interpret fractions, decimals and percentages as one another\n\n## Worked Examples\n\n1 - Adding and Subtracting Fractions\nWhen adding and subtracting fractions, there is one simple rule you must remember:\n\nFind the lowest common denominator\n\nThe lowest common denominator is the lowest number which the denominators will both go into. After you have worked out this value, multiply the number and denominator of each fraction by the same number.\n\nAfter doing this, add or subtract the numerator values whilst keeping the denominator value the same.\n\nExample\n(a) - Work out\n\n$\\frac{4}{6} + \\frac{2}{8}$\n\nSolution\n(a) - The lowest common denominator for 6 and 8 is 24\n\n$6*4 = 24$\n$8*3 = 24$\n\nTherefore, you must multiply the numerators of each fraction by these values.\n\n4/6 becomes 16/24 and 2/8 becomes 6/24\n\n$\\frac{{16}}{{24}} + \\frac{6}{{24}} = \\frac{{22}}{{24}}$\n\nThis value can be simplified to,\n\n$\\frac{{11}}{{12}}$\n\nTherefore,\n\n$\\frac{4}{6} + \\frac{2}{8} = \\frac{{11}}{{12}}$\n\n2 - Fractions of a quantity\nDuring your exam you will be asked to find the fraction of a quantity. There are two methods of working this out, which are displayed as follows:\n\nExample\n(a) - What is 5/6 of 30?\n\nSolution\n(a) - Method One\n\n• Work out 1/6 of 30\n• Multiply this value by 5\n\n1/6 of 30 is 30 ÷ 6 = 5\n\nTherefore to work out 5/6 of 30 you multiply 5 by 5\n\n5/6 of 30 = 5x5 = 25\n\n(a) - Method 2\n\n• Multiply 5/6 by 30\n$\\frac{5}{6}*30 = \\frac{5}{6}*\\frac{{30}}{1} = \\frac{{150}}{6} = 25$\n\n3 - Equivalent Fractions\nA fraction can be written in several ways and still have the same value. These are referred to as equivalent fractions.\n\nYou can produce lots of equivalent fractions by multiplying or dividing the top and bottom by the same number.\n\nFor example:\n\n4/8 has the same value as 1/2\n\nThese values are the same because when you multiply or divide both the top and bottom by the same number, the fraction keeps the same value.\n\n4 - Simplified Fractions\nThrough this process of recognising equivalent fractions, you can reduce large fractions into simplified values of themselves. These are referred to as simplified fractions.\n\nDuring your exam, you may be asked to simplify a fraction, or fill in a missing number. When doing so, you must remember the following rules:\n\n• You must multiply or divide both the numerator and denominator by the same value\n• Only divide by a value which will ensure the numerator and denominator remain whole numbers\n• Only multiply or divide, never add or subtract, to calculate an equivalent fraction\n\nExample\n(a) - Simplify the fraction 20/35\n\nSolution\n(a) - 20 and 35 are both dividable by 5\n\n$20/5 = 4$\n$35/5 = 7$\n\nTherefore, 20/35 can be simplified to 4/7\n\n5 - Fractions and decimals\nDuring your exam, you may be asked to convert a fraction into a decimal. To do this, you divide the numerator by the denominator.\n\nExample\n(a) - Convert 3/4 to a decimal\n\nSolution\n(a) -\nTo convert 3/4 to a decimal, you divide 3 by 4\n\nTherefore,\n\n$3/4 = 0.75$\n\nIn examples such as the one demonstrated above, some decimals will terminate. However, there are other fractions which, when converted into decimal form, will have a recurring value.\n\nFor example:\n\n$1/3 = 0.33333333.....$\n\nDuring your exam, you may also be asked to convert a decimal into a fraction. When doing so, it is important to remember that the denominator will be a value of either 10, 100 r 1000 depending on the amount of decimal places.\n\nExample\n(a) - Convert 0.4 into a fraction\n\nSolution\n(a) -\n0.4 is four tenths of 1, therefore as a fraction it can be written as 4/10. You then simplify this fraction using the method explained above.\n\n$0.4 = 4/10 = 2/5$\n\nTherefore 0.4 can be converted into the fraction 2/5\n\nExample\n(b) - Convert 0.35 into a fraction\n\nSolution\n(b) -\n0.35 is 35 hundredths of 1, therefore as a fraction it can be written as 35/100.\n\nWhen simplified,\n\n$35/100 = 7/20$\n\nTherefore 0.35 can be converted into the fraction 7/20\n\nExample\n(c) - Convert 0. 240 into a fraction\n\nSolution\n(c) -\n0.240 is 240 thousandths of 1, therefore as a fraction it can be written as 240/1000 . When simplified,\n\n$240/1000 = 6/25$\n\nTherefore 0.240 can be converted into the fraction 6/25\n\n6 - Fractions and decimals: Higher Tier\nIf you are sitting the higher tier paper, you will be asked to convert fractions into decimals and where the value may recur. For example, 1/3 which when converted gives a recurring value of 0.333333...\n\nWhen converting these values, it is necessary to find the prime factors of the denominator.\n\nAs a rule, when the prime factors of the denominator of a fraction in its simplest form are only 2 and/or 5, then its decimal will terminate.\n\nTherefore, to work out whether a value will terminate, it is necessary to work out whether its prime factors are 2 and/or 5.\n\nExample\n(a) - Convert 3/20 into a decimal\n\nSolution\n(a) -\n\n$3/20 = 3/(2*2*5) = 0.15$\n\nExample\n(b) - Convert 2/9 into a decimal\n\nSolution\n(b) -\n\n$2/9 = 2/(3*3) = 0.22222...$\n\nTherefore, this value will not terminate.\n\n7 - Fractions and Percentages\nDuring your exam, you may be asked to convert a fraction to a percentage. To do this, you must multiply the fraction by 100.\n\nExample\n(a) - Convert 4/10 into a percentage\n\nSolution\n(a) -\n4/10 is equivalent to 4/10 x 100 = 40%\n\nTherefore 4/10 can be converted into the percentage 40%\n\nYou may also be asked to convert a percentage to a fraction. To do this, you must present the percentage value as the numerator in a fraction with the denominator 100.\n\nExample\n(a) - Convert 12% into a fraction\n\nSolution\n(a) -\n12% as a fraction can be displayed as 12/100\n\nThis fraction can then be simplified to 6/50\n\nTherefore 12% can be converted into the fraction 6/50\n\n## Exam Tips\n\n1. Remember that percentages are simply fractions out of 100, and that decimals are simply tenths, hundredths and thousandths of 1\n2. When multiplying and dividing fractions, always search for the lowest common denominator\n3. Multiply and divide both the numerator and denominator by the same value\n4. Only divide by a value which will ensure the numerator and denominator will remain whole numbers\n5. Only multiple and divide, never add or subtract, to work out an equivalent fraction\n6. Write down ALL of your working out, no matter how simple it may seem!\n\n## Topic Summary\n\nUltimately, although fraction based questions may appear complicated at first, once you have learned the correct methods they are easy to understand and solve. Above all else, remember to find the lowest common denominator. Once you have this value, you can easily follow the steps displayed in the examples above in order to add, subtract, multiply, divide and convert fractions with ease!\n\n## Related Topics\n\n• Indices\n• Problem Solving with Decimals and Percentages\n• Accuracy of Measurement Problems\n• Arithmetic with Positive and Negative Integers\n• Standard Form\n• Rational and Irrational Numbers\n• Combinations"
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.8855107,"math_prob":0.9926063,"size":6946,"snap":"2019-51-2020-05","text_gpt3_token_len":1641,"char_repetition_ratio":0.17847882,"word_repetition_ratio":0.07465135,"special_character_ratio":0.2433055,"punctuation_ratio":0.093005955,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9998479,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-01-21T17:01:22Z\",\"WARC-Record-ID\":\"<urn:uuid:dfd1800a-238f-4f05-a6d8-4e86ae01d0d8>\",\"Content-Length\":\"44019\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:1101fcad-82c8-47bf-8c24-bcdcff16c71c>\",\"WARC-Concurrent-To\":\"<urn:uuid:f0257b54-f213-45fc-a596-2e6ef664adeb>\",\"WARC-IP-Address\":\"104.45.14.249\",\"WARC-Target-URI\":\"https://mathsdoctor.co.uk/revision-help/gcse/number/arithmetic-with-fractions/\",\"WARC-Payload-Digest\":\"sha1:LJUMMGC6MPCPR3NI2FSCKFAIKTLRWF4M\",\"WARC-Block-Digest\":\"sha1:2DYG2T7ORN5RHKVYO53SYNKVAEIMMDIQ\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-05/CC-MAIN-2020-05_segments_1579250604849.31_warc_CC-MAIN-20200121162615-20200121191615-00126.warc.gz\"}"} |
https://fr.mathworks.com/matlabcentral/cody/solutions/1869548 | [
"Cody\n\n# Problem 8058. Kinetic Energy\n\nSolution 1869548\n\nSubmitted on 9 Jul 2019 by Evan\nThis solution is locked. To view this solution, you need to provide a solution of the same size or smaller.\n\n### Test Suite\n\nTest Status Code Input and Output\n1 Pass\nm = 20; v = 25 y_correct = 6250; assert(isequal(kinetic_energy(m,v),y_correct))\n\nv = 25\n\n2 Pass\nm = 1; v = 4; y_correct = 8; assert(isequal(kinetic_energy(m,v),y_correct))\n\n3 Pass\nm = 6; v = 9; y_correct = 243; assert(isequal(kinetic_energy(m,v),y_correct))"
] | [
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https://apptopia.com/ios/app/1454635384/about | [
"Description\n\nMath problems have you stuck? With Math Lens, you can snap a photo of your entire math paper with algebra and calculus problems, and in seconds, get the correct results on your paper directly.\n\nHandwritten or printed problems, it doesn't matter. Math Lens can recognize them either way. Your results will show step-by-step explanations and graphs to help you better understand the problem.\n\n=== Math Lens supports ===\n\nMath Functions for Numbers, Fractions, Decimals\nb. Subtraction\nc. Multiplication\nd. Division\ne. Comparing\nf. Mixed numbers\ng. Converting\n\nSimplifying Algebraic Expressions\n\nPowers And Roots\nb. Subtraction\nc. Multiplication\nd. Division\ne. Comparing\nf. Scientific notation\n\nLinear Functions\na. Linear equations\nb. Linear inequalities\nd. Graphs\n\nd. Graphs\n\nTrigonometric Functions\na. Trigonometric equations\nb. Systems\nc. Graphs\n\nCalculus\na. Limits\nb. Derivatives\nc. Integrals\n\n-----------------------------\n\nEmail: support@mathlens.com\n\nScreenshots",
null,
"",
null,
"",
null,
"",
null,
"Version History\n\nLaunched Mar 10, 2019 (4 months ago).\n\nReleasing new versions every about 1 month, on average.\n\n Jun 182019 (Current)Version 1.21. Redesigned the app to show answers on your entire math paper directly 2. Support to use the smart calculator to edit the math problem 3. General improvements to math problem recognition engine Apr 162019 Version 1.1.11. Bug fix and performance improvements --------- Recent update --------- 1. Various fixes and improvements to math problem recognition engine 2. New step-by-step solutions for long division, multiplication, addition and substraction 3. Optimized the feature of graphing function Apr 122019 Version 1.11. Various fixes and improvements to math problem recognition engine 2. New step-by-step solutions for long division, multiplication, addition and substraction 3. Optimized the feature of graphing function Mar 102019 Version 1.0 Previous 3 versions\n\nRatings\n\nThis app has no ratings in the last 30 days.\n\n17\n\nTotal Ratings\n\n 5 9 4 1 3 1 2 0 1 6"
] | [
null,
"https://d1nxzqpcg2bym0.cloudfront.net/itunes_connect/1454635384/032b9d3a-5dcf-11e9-814b-17c8fe33a0f8/640",
null,
"https://d1nxzqpcg2bym0.cloudfront.net/itunes_connect/1454635384/040e899c-5dcf-11e9-88c6-638812796fbe/640",
null,
"https://d1nxzqpcg2bym0.cloudfront.net/itunes_connect/1454635384/04e2d30a-5dcf-11e9-88ee-738b0cf87096/640",
null,
"https://d1nxzqpcg2bym0.cloudfront.net/itunes_connect/1454635384/05b7a58a-5dcf-11e9-80e3-29a2b44cfec8/640",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.71293104,"math_prob":0.8470319,"size":1553,"snap":"2019-26-2019-30","text_gpt3_token_len":402,"char_repetition_ratio":0.12588766,"word_repetition_ratio":0.06113537,"special_character_ratio":0.24661945,"punctuation_ratio":0.17482518,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.96978647,"pos_list":[0,1,2,3,4,5,6,7,8],"im_url_duplicate_count":[null,1,null,1,null,1,null,1,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-06-25T03:31:39Z\",\"WARC-Record-ID\":\"<urn:uuid:dcf3b208-39dd-4724-a8d5-4246bd1c57f0>\",\"Content-Length\":\"28409\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:5ec5f30a-7d31-462b-8ee6-6c5eb94fa9d0>\",\"WARC-Concurrent-To\":\"<urn:uuid:eab92764-d848-433d-81d3-b8082e63e13e>\",\"WARC-IP-Address\":\"54.225.164.231\",\"WARC-Target-URI\":\"https://apptopia.com/ios/app/1454635384/about\",\"WARC-Payload-Digest\":\"sha1:2EFA2B5TFQDKI7MH37ULEMWOYD2RF6H7\",\"WARC-Block-Digest\":\"sha1:HAKWUKGI32FOAPGBAABTIVT4ILUTKTPT\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-26/CC-MAIN-2019-26_segments_1560627999787.0_warc_CC-MAIN-20190625031825-20190625053825-00263.warc.gz\"}"} |
https://nl.mathworks.com/matlabcentral/answers/1578335-to-solve-the-problem-index-in-position-1-exceeds-array-bounds-index-must-not-exceed-10?s_tid=prof_contriblnk | [
"# to solve the problem: Index in position 1 exceeds array bounds. Index must not exceed 10\n\n9 views (last 30 days)\nELISABETTA BILLOTTA on 3 Nov 2021\nCommented: Adam on 3 Nov 2021\ni have this code:\nx = [0 0 71 355 676];\nv = [0 7 30 70];\nxq = z1; %distance\nvq2 = interp1(x,v,xq,'linear'); % velocity\nvq2(isnan(vq2))=100;\nd= [-160 -125 -89 -53 -17 18 54 90 126 161]; % reference angles on the grid\nvel_thr= [0:100]; % sums of speeds to be considered\nfor i=1:length(z2) % z2 is angles\nangsel=z2(i)*180/pi;\n[tmp1, icol1]=min(abs(angsel-d));\n[tmp2, icol2]=min(abs(360+angsel-d));\nif tmp1<tmp2\nicol(i)= icol1;\nelse\nicol(i)= icol2;\nend\nvelsel=vq2(i);\nitmp=find(velsel>=vel_thr);\nif isempty(itmp);\nirow(i)=1;\nelse\nirow(i)=itmp(end);\nend\nprobfile=[cnorm(1,:)*100;cumsum(cnorm(2:end,:)*100,'reverse')]; %cnorm is 10x10 double\nprobfile2=fliplr(probfile);\nprob(i)=probfile2(irow(i),icol(i));\nend\neverything is correct but on the line \"prob(i)=probfile2(irow(i),icol(i))\" it stops and the this error:\n\"Index in position 1 exceeds array bounds. Index must not exceed 10.\"\nhow can I solve this problem?\nthanksss\n##### 1 CommentShowHide None\nAdam on 3 Nov 2021\nEasiest way to error check these is just to use the command line and check what the following values are at the point when the code errors:\nirow(i)\nicol(i)\nsize(probfile2)\nirow(i) and icol(i) must be less than or equal to the 1st and 2nd elements of that size output, respectively.\nIt is too hard for me to tell by just glancing at the code what values these may have and in what iteration (i) they may fail, especially since z2, whose size defines the range over which i iterates appears to not be defined in this part of the code.\n\nJon on 3 Nov 2021\nFrom the error message it looks like the variable irow(i), that is the \"Index in position 1\" is bigger than 10, which apparently is the row dimension of the variable probfile2. So MATLAB can't execute that line because you are asking for row 11 or maybe some bigger number of an array that only has 10 rows.\nI tried running your code to see if I could give you more specific advice but the snippet you have doesn't define the variable z1, so it wouldn't run. If you want to attach more code to demonstrate the problem then please attach it, but use the code button in the MATLAB Answers toolbar so it will be nicely formatted and easily copied"
] | [
null
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https://www.shaalaa.com/question-paper-solution/maharashtra-state-board-ssc-geometry-mathematics-2-10th-10th-standard-board-exam-2020-2021-shaalaacom-model-set-2_17916 | [
"# Geometry Shaalaa.com Model Set 2 2019-2020 SSC (English Medium) 10th Standard Board Exam Question Paper Solution\n\nGeometry [Shaalaa.com Model Set 2]\nDate: March 2020\nDuration: 2h\n\n 1\n 1.A | MCQs\n 1.A.i\n\nFour alternative answers for the following question is given. Choose the correct alternative.\n\nTwo circles intersect each other such that each circle passes through the centre of the other. If the distance between their centres is 12, what is the radius of each circle?\n\n6 cm\n\n12 cm\n\n24 cm\n\ncan’t say\n\nConcept: Theorem of Touching Circles\nChapter: [0.03] Circle\n 1.A.ii\n\nIf in ∆DEF and ∆PQR, ∠D ≅ ∠Q, ∠R ≅ ∠E then which of the following statements is false?",
null,
"$\\frac{EF}{PR} = \\frac{DF}{PQ}$\n\n$\\frac{DE}{PQ} = \\frac{EF}{RP}$\n\n$\\frac{DE}{QR} = \\frac{DF}{PQ}$\n\n$\\frac{EF}{RP} = \\frac{DE}{QR}$\n\nConcept: Similarity of Triangles\nChapter: [0.01] Similarity\n 1.A.iii\n\nSome question and their alternative answer are given. Select the correct alternative.\n\nIf a, b, and c are sides of a triangle and a+ b= c2, name the type of triangle.\n\nObtuse angled triangle\n\nAcute angled triangle\n\nRight-angled triangle\n\nEquilateral triangle\n\nConcept: Right-angled Triangles and Pythagoras Property\nChapter: [0.02] Pythagoras Theorem\n 1.A.iv\n\nSelect the correct alternative for the following question.\n\nThe number of tangents that can be drawn to a circle at a point on the circle is ............... .\n\n3\n\n2\n\n1\n\n0\n\nConcept: Construction of a Tangent to the Circle at a Point on the Circle\nChapter: [0.04] Geometric Constructions\n 1.B\n 1.B.i\n\nFind the ratio in which point T(–1, 6)divides the line segment joining the points P(–3, 10) and Q(6, –8).\n\nConcept: Division of a Line Segment\nChapter: [0.04] Geometric Constructions [0.05] Co-ordinate Geometry\n 1.B.ii\n\nProve that:\n\n$\\cos^2 \\theta\\left( 1 + \\tan^2 \\theta \\right) = 1$\n\nConcept: Application of Trigonometry\nChapter: [0.06] Trigonometry\n 1.B.iii\n\nFind the volume of a cone if the radius of its base is 1.5 cm and its perpendicular height is 5 cm.\n\nConcept: Concept of Surface Area, Volume, and Capacity\nChapter: [0.07] Mensuration\n 1.B.iv\n\nFind the coordinates of midpoint of the segment joining the points (22, 20) and (0, 16).\n\nConcept: The Mid-point of a Line Segment (Mid-point Formula)\nChapter: [0.05] Co-ordinate Geometry\n 2\n 2.A | Solve any 2 of the following\n 2.A.i\n\nIn the given figure, chord MN and chord RS intersect at point D.\n(1) If RD = 15, DS = 4, MD = 8 find DN\n(2) If RS = 18, MD = 9, DN = 8 find DS",
null,
"Concept: Theorem of External Division of Chords\nChapter: [0.03] Circle\n 2.A.ii\n\nIn the given figure, if AB || CD || FE then Find x and AE.",
null,
"Concept: Property of an Angle Bisector of a Triangle\nChapter: [0.01] Similarity\n 2.A.iii\n\nIf tanθ = 2, find the values of other trigonometric ratios.\n\nConcept: Trigonometric Ratios of Complementary Angles\nChapter: [0.06] Trigonometry\n 2.B | Solve any 4 of the following\n 2.B.i",
null,
"Observe the measures of pots In the given figure. How many jugs of water can the cylindrical pot hold?\n\nConcept: Surface Area and Volume of Different Combination of Solid Figures\nChapter: [0.07] Mensuration\n 2.B.ii\n\nDetermine whether the point is collinear.\nA(1, –3), B(2, –5), C(–4, 7)\n\nConcept: Distance Formula\nChapter: [0.05] Co-ordinate Geometry\n 2.B.iii\n\nIf $\\sec\\theta = \\frac{13}{12}$, find the values of other trigonometric ratios.\n\nConcept: Trigonometric Ratios of Complementary Angles\nChapter: [0.06] Trigonometry\n 2.B.iv\n\nIn the given figure, altitudes YZ and XT of ∆WXY intersect at P. Prove that,\n(1) ▢WZPT is cyclic.\n(2) Points X, Z, T, Y are concyclic.",
null,
"Concept: Angle Subtended by the Arc to the Centre\nChapter: [0.03] Circle\n 2.B.v\n\nProve that (sinθ - cosθ + 1)/(sinθ + cosθ - 1) = 1/(secθ - tanθ)\n\nConcept: Application of Trigonometry\nChapter: [0.06] Trigonometry\n 3\n 3.A | Solve any 1 of the following\n 3.A.i\n\nDraw a circle with centre P and radius 3.4 cm. Take point Q at a distance 5.5 cm from the centre. Construct tangents to the circle from point Q.\n\nConcept: To Construct Tangents to a Circle from a Point Outside the Circle.\nChapter: [0.04] Geometric Constructions\n 3.A.ii\n\nFor finding AB and BC with the help of information given in the figure, complete following activity.\n\nAB = BC ..........",
null,
"$\\therefore \\angle BAC =$",
null,
"$\\therefore AB = BC =$",
null,
"$\\times AC$\n\n$=$",
null,
"$\\times \\sqrt{8}$\n\n$=$",
null,
"$\\times 2\\sqrt{2}$\n\n=",
null,
"",
null,
"Concept: Right-angled Triangles and Pythagoras Property\nChapter: [0.02] Pythagoras Theorem\n 3.B | Solve any 2 of the following\n 3.B.i\n\nLine l touches a circle with centre O at point P. If radius of the circle is 9 cm, answer the following.\n(1) What is d(O, P) = ? Why ?\n(2) If d(O, Q) = 8 cm, where does the point Q lie ?\n(3) If d(OQ) = 15 cm, How many locations of point Q are line on line l? At what distance will each of them be from point P?",
null,
"Concept: Theorem of Touching Circles\nChapter: [0.03] Circle\n 3.B.ii\n\nIn the given fig, bisectors of ∠B and ∠C of ∆ABC intersect each other in point X. Line AX intersects side BC in point Y. AB = 5, AC = 4, BC = 6 then find \"AX\"/\"XY\".",
null,
"Concept: Property of an Angle Bisector of a Triangle\nChapter: [0.01] Similarity\n 3.B.iii\n\nDraw a circle with radius 4.1 cm. Construct tangents to the circle from a point at a distance 7.3 cm from the centre.\n\nConcept: To Construct Tangents to a Circle from a Point Outside the Circle.\nChapter: [0.04] Geometric Constructions\n 3.B.iv\n\nIf A (20, 10), B(0, 20) are given, find the coordinates of the points which divide segment AB into five congruent parts.\n\nConcept: Division of a Line Segment\nChapter: [0.04] Geometric Constructions [0.05] Co-ordinate Geometry\n 4 | Solve any 2 of the following\n 4.A\n\nA toy is in the form of a cone of radius 3.5 cm mounted on a hemisphere of same radius. The total height of the toy is 15.5 cm. Find the total surface area of the toy [Use π =22/7]\n\nConcept: Surface Area of a Combination of Solids\nChapter:\n 4.B\n\nProve that the perpendicular at the point of contact to the tangent to a circle passes through the centre\n\nConcept: Number of Tangents from a Point on a Circle\nChapter: [0.03] Circle\n 4.C\n\nIn ∆ABC, B - D - C and BD = 7, BC = 20 then Find following ratio.",
null,
"\"A(∆ ABD)\"/\"A(∆ ADC)\"\n\nConcept: Properties of Ratios of Areas of Two Triangles\nChapter: [0.01] Similarity\n\nIn the given fig, XY || seg AC. If 2AX = 3BX and XY = 9. Complete the activity to Find the value of AC.",
null,
"Activity : 2AX = 3BX\n\n∴ \"AX\"/\"BX\" = square/square\n\n\"AX +BX\"/\"BX\" = (square + square)/square ...(by componendo)\n\n\"AB\"/\"BX\" = square/square ...(I)\n\nΔBCA ~ ΔBYX ... square test of similarity,\n\n∴ \"BA\"/\"BX\" = \"AC\"/\"XY\" ...(corresponding sides of similar triangles)\n\n∴ square/square = \"AC\"/9\n\n∴ AC = square ...[From(I)]\n\nConcept: Property of Three Parallel Lines and Their Transversals\nChapter: [0.01] Similarity\n 5 | Solve any 1 of the following\n 5.A\n\nIn the given figure, point T is in the interior of rectangle PQRS, Prove that, TS+ TQ= TP+ TR(As shown in the figure, draw seg AB || side SR and A-T-B)",
null,
"Concept: Right-angled Triangles and Pythagoras Property\nChapter: [0.02] Pythagoras Theorem\n 5.B\n\nIn the given figure, A is the centre of the circle. ∠ABC = 45° and AC = 7√2 cm. Find the area of segment BXC.",
null,
"Concept: Areas of Sector and Segment of a Circle\nChapter: [0.07] Mensuration\n\n#### Request Question Paper\n\nIf you dont find a question paper, kindly write to us\n\nView All Requests\n\n#### Submit Question Paper\n\nHelp us maintain new question papers on Shaalaa.com, so we can continue to help students\n\nonly jpg, png and pdf files\n\n## Maharashtra State Board previous year question papers 10th Standard Board Exam Geometry with solutions 2019 - 2020\n\nMaharashtra State Board 10th Standard Board Exam Geometry question paper solution is key to score more marks in final exams. Students who have used our past year paper solution have significantly improved in speed and boosted their confidence to solve any question in the examination. Our Maharashtra State Board 10th Standard Board Exam Geometry question paper 2020 serve as a catalyst to prepare for your Geometry board examination.\nPrevious year Question paper for Maharashtra State Board 10th Standard Board Exam Geometry-2020 is solved by experts. Solved question papers gives you the chance to check yourself after your mock test.\nBy referring the question paper Solutions for Geometry, you can scale your preparation level and work on your weak areas. It will also help the candidates in developing the time-management skills. Practice makes perfect, and there is no better way to practice than to attempt previous year question paper solutions of Maharashtra State Board 10th Standard Board Exam.\n\nHow Maharashtra State Board 10th Standard Board Exam Question Paper solutions Help Students ?\n• Question paper solutions for Geometry will helps students to prepare for exam.\n• Question paper with answer will boost students confidence in exam time and also give you an idea About the important questions and topics to be prepared for the board exam.\n• For finding solution of question papers no need to refer so multiple sources like textbook or guides."
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https://deepai.org/publication/focus-of-attention-improves-information-transfer-in-visual-features | [
"",
null,
"# Focus of Attention Improves Information Transfer in Visual Features\n\nUnsupervised learning from continuous visual streams is a challenging problem that cannot be naturally and efficiently managed in the classic batch-mode setting of computation. The information stream must be carefully processed accordingly to an appropriate spatio-temporal distribution of the visual data, while most approaches of learning commonly assume uniform probability density. In this paper we focus on unsupervised learning for transferring visual information in a truly online setting by using a computational model that is inspired to the principle of least action in physics. The maximization of the mutual information is carried out by a temporal process which yields online estimation of the entropy terms. The model, which is based on second-order differential equations, maximizes the information transfer from the input to a discrete space of symbols related to the visual features of the input, whose computation is supported by hidden neurons. In order to better structure the input probability distribution, we use a human-like focus of attention model that, coherently with the information maximization model, is also based on second-order differential equations. We provide experimental results to support the theory by showing that the spatio-temporal filtering induced by the focus of attention allows the system to globally transfer more information from the input stream over the focused areas and, in some contexts, over the whole frames with respect to the unfiltered case that yields uniform probability distributions.\n\n## Code Repositories\n\n### focus_of_attention_improves_info_transfer\n\nCode to reproduce the experiments on our NeurIPS2020 paper\n\n##### This week in AI\n\nGet the week's most popular data science and artificial intelligence research sent straight to your inbox every Saturday.\n\n## 1 Introduction\n\nNowadays the most popular benchmarks in the machine learning community are composed of batches of data that are commonly processed in an offline manner using stochastic updates of the model parameters, periodically shuffling the available samples\n\n(Russakovsky et al., 2015; Krizhevsky, 2009; Damen et al., 2018). A smaller effort has been devoted by the research community to the direction of focusing on a single, potentially life-long video, in which the model continuously processes a stream of frames, that is a very natural setting resembling the flow of information that hits the eyes of each human Betti et al. (2020b). An important feature of the human visual system that is frequently neglected in several algorithms is the attention mechanism that drives the gaze over different spatial regions of the input stimulus. As a matter of fact, it is implicitly assumed that all the pixels equally contribute to the learning process, assuming a uniform probability distribution of their coordinates over the retina. In the last few years, a lot of importance has been devoted to attention in neural models, for example in learning to play games Zhang (2019), in learning task-specific attention Mnih et al. (2014), or in mixing bottom-up and top-down attention Xiao et al. (2015). A different research direction, closer to Neuroscience, is the one that specifically studies saliency in the context of the human visual attention systems Borji and Itti (2012), where dynamic models of visual attention have been recently proposed, able to predict in an online manner the trajectory of the attention Zanca and Gori (2017); Zanca et al. (2019).\n\nIn this paper, we cast the problem of processing a visual stream in a truly online setting, motivated by recent studies that connected learning over time and classical mechanics Betti et al. (2020b, a, 2019). The framework proposed in Betti et al. (2020b) naturally deals with learning problems in which time plays a crucial role, and it is well-suited to learn from streams of visual data in a principled way. The temporal trajectories of the variables of the learning problem are modeled by the so called 4th order Cognitive Action Laws (CALs) that come from stationarity conditions of a functional, as it happens for generalized coordinates in classical mechanics. We intersect these ideas with the recent human-like attention model of Zanca et al. (2019), that has shown state-of-the art results in focus estimation. Motion and visual features are treated as a mass distribution in the gravitational field that determines the trajectory of the focus of attention. The focus of attention implements a filtering procedure on the input video, allowing the system to deal only with those areas that would attract the human attention. We propose a 2nd order model that, under some mild conditions, leads to a simplified and more manageable instance of the CALs, yielding ODEs of same order of the ones that drive the attention.\n\nWith the goal of studying the impact of the focus of attention dynamics in videos, we consider the problem of transferring information from the input visual stream to the output space of a neural architecture that performs pixel-wise predictions Betti et al. (2020a, 2019). This problem consists in maximizing the Mutual Information (MI) index Betti et al. (2020b). One of the key issues with MI maximization over time, especially when focusing the attention on a few pixels, is the fact that stochastic updates of the model parameters do not keep track of the entropy of the output space due to the data processed so far, leading to poorly informed updates. We investigate the case in which the global changes in the entropy of the output space are approximated by introducing a specific constraint or a moving average. It turns out that, when learning over the focus trajectory, the MI index grows more significantly over the focused areas with respect to the unfiltered case, and, in some configurations, it is also larger than considering other distributions of the pixel coordinates. This suggests that filtering the information by a bottom-up attention model helps the system in transferring information from the whole stream.\n\nThe topic of MI maximization has recently attracted the attention of several researches Belghazi et al. (2018); Hjelm et al. (2019); Tian et al. (2019); Oord et al. (2018); Tschannen et al. (2020). Most of the recent works are about customized MI-based criteria to learn representations for downstream tasks, that is not the case of this paper. Moreover, Hjelm et al. (2019); Tian et al. (2019) are based on surrogate functions that loosely approximate Tschannen et al. (2020) the continuous MI formulation, while here we directly consider the discrete MI index, that, for instance, has been previously used as criterion to relate different views of the input data Hu et al. (2017) or in clustering Melacci and Gori (2012). The information transferred by multi-layer networks is discussed in the context of the popular information bottleneck principle by Naftali Tishby and other authors as a mean to study deep network internal dynamics Tishby and Zaslavsky (2015); Shwartz-Ziv and Tishby (2017); Saxe et al. (2019).\n\nIn summary, the contributions of this paper are: (1) we study human-like attention mechanisms in conjunction with learning in video data, (2) considering a new 2nd order differential model and (3) evaluating the impact of different criteria to approximate the entropy estimate over the whole stream. This paper is organized as follows. Section 2 describes the learning framework, 2nd order models, and the problem of MI maximization. Section 3 is about injecting the focus of attention dynamics, while experiments are reported in Section 4. Section 5 concludes the paper with ideas for future work.\n\n## 2 Learning over Time\n\nWe consider the problem of processing a stream of data over time and, in particular, a stream of video frames from a target source, being the frame at time in the time horizon\n\n. The stream is processed by a neural network whose weights and biases at time\n\nare represented by the generic vector variable\n\n, while , are respectively its first and second derivatives. Our work is rooted in the ideas presented in Betti et al. (2020b, a, 2019), where learning is described in analogy with classical mechanics, as a variational problem whose objective is to find a stationary point of the following functional of the maps ,\n\n Γ(ξ)(w):=∫T0L(t,w(t),˙w(t),¨w(t))dt=∫T0h(t)(K(˙w(t),¨w(t))−ξV(w(t),u(t)))dt. (1)\n\nThe Lagrangian is composed of a kinetic energy and a potential energy , while , when appropriately chosen, is responsible of introducing energy dissipation. The term is selected in function of the way is implemented (see Betti et al. (2020a) for details111In this paper we changed the notation w.r.t. Betti et al. (2020a) in order to simplify the description of our approach.). In particular, in Betti et al. (2020a, 2019, b) we have , ,\n\nis composed of the loss function\n\nof the considered problem and a quadratic regularizer on , and includes the squared norm of the derivatives plus their dot product, leading to\n\n Γ(−1)(w)≡Γ(w)=∫T0eθt(α2|¨w(t)|2+β2|˙w(t)|2+γ˙w(t)⋅¨w(t)+k2|w(t)|2+U(w(t),u(t)))dt, (2)\n\nwhere and , , , are custom positive scalars, is the Euclidean norm in and is the standard scalar product in , being the size of .\n\nThe Euler-Lagrange (EL) equations of Eq. (2) yield the Cognitive Action Laws (CALs), 4th order differential equations that, when integrated, allows to be updated over time. In particular, they are222We removed the time index to simplify the notation. We will do it occasionally also in the rest of the paper.\n\n αw(4)+2θαw(3)+(θ2α+θγ−β)¨w+(θ2γ−θβ)˙w+kw+∇U(w,u)=0, (3)\n\nbeing and the fourth and third derivatives of , respectively, and is the gradient of with respect to its first argument. Cauchy’s initial conditions can be provided on and , while stationarity conditions of prescribe that Eq. (3) must be paired with boundary conditions on the right border (). Thus, in order to solve the problem of determining in a causal way (i.e. in such a way that the solution at time does not depend on values in ), the fulfilment of the boundary conditions in is approximated in Betti et al. (2020a) by introducing a mechanism that sets ( “resets”) to zero all the derivatives up to , whenever their norms become too large. See Betti et al. (2020a) for more details on CALs.\n\n### 2.1 Second-Order Laws\n\nDespite their robust principled formulation, the main drawbacks of the 4th order CALs is the difficulty in tuning the parameters that weigh the contribute of the derivatives, and the computational/memory burden due to the integration of a 4th order ODE. Moreover, the theoretical guarantees on the stability of Eq. (3) are experimentally shown to not be necessarily needed, mostly due to the aforementioned derivative reset procedure Betti et al. (2020a). For these reasons, in this paper we will use the CAL theory in a particular causal regime of the parameters for which two important simplifications are attained. First, the dynamics of the weights are described by a 2nd order ODE (instead of Eq. (3)). Second, we get direct causality without the need of any reset mechanisms.\n\nThe limiting procedure that leads to the 2nd order laws is based on a conjecture by De Giorgi Ambrosio et al. (2006) which has been subsequently proved and studied in Stefanelli (2011); Serra and Tilli (2012); Liero and Stefanelli (2013). In detail, we consider a reparametrization in terms of of the functional, where , , . This allows us to rewrite Eq. (2) in line with De Giorgi’s functional,\n\n Γε(w):=∫T0e−t/ε(αε22|¨w(t)|2+βε2|˙w(t)|2+k2|w(t)|2+U(w(t),u(t)))dt, (4)\n\nwhere we also chose, for simplicity, . Letting , the minima of the functional with fixed initial conditions on and converges to the solution of a Cauchy problem based on a 2nd order differential equation, thus gaining full causality, i.e., measures the “degree of causality” of the solution. Notice that the factor in Eq. (4) becomes peaked on as , and the minimization procedure of will be mainly concerned in the minimization of the loss calculated at . At a first glance, this might seem counter-intuitive. However, it becomes a useful feature when considered in conjunction with the properties of the input signal . Let us indicate with the temporal scale of , that is a small time span under which the variations of are semantically negligible. The whole temporal interval can be partitioned into disjoint intervals , in each of which the aforementioned picky behaviour is not critical due to the temporal scale of . The minimization of Eq. (4) can be iteratively defined by minimizing in each interval, where the conditions on the left boundary are given by the solution of the minimization in the previous interval. When , the minimization problem can be well interpreted in terms of the value of , for .\n\nTo introduce the EL equations of the newly introduced problem, for simplicity, we will describe the limiting procedure in the interval , that applies to each of the previously described intervals. The EL equations for the minimizer of with initial conditions and are\n\n {ε2αw(4)(t)−2εαw(3)(t)+(αϵ2−εβ)¨w(t)+β˙w(t)+kw(t)+∇U(w(t),u(t))=0;w(0)=w0,α˙w(0)=αw1,α¨w(T)=0,αεw(3)(T)=β˙w(T), (5)\n\nand the following theorem holds:\n\n###### Theorem 1.\n\nThe solution of the problem (5) converges (weakly in to the solution of\n\n {α¨w(t)+β˙w(t)+kw(t)+∇U(w(t),t)=0;w(0)=w0,˙w(0)=w1. (6)\n\nEquations (6) are 2nd order CALs. They are simpler than the 4th order CALs of Eq. (3), even if they maintain their principled nature. See the supplementary material for formal proofs and further details.\n\n### 2.2 Mutual Information in Video Streams\n\nWe consider the problem of transferring information from an input visual stream to the output space of a multi-layer convolutional network with layers, that processes each frame and yields pixel-wise predictions. This corresponds to the maximization of the Mutual Information (MI) from the pixels of the input frames to the -dimensional output space yielded by the units of the last layer, being the size of the filter bank in layer\n\n. Hyperbolic tangent is used as activation function in each layer\n\n, while the last layer is equipped with a softmax activation, generating probabilities , being a pair of pixel coordinates and the processed frame. This problem is studied in Betti et al. (2020b) and related papers Betti et al. (2019, 2020a), where single-layer models (or stacks of sequentially trained single-layer models) are considered, while, in this paper, we exploit a deep network trained end-to-end. Previous approaches based on kernel machines can be found in Gori et al. (2016, 2012).\n\nIn order to define the MI index, we consider a generic, time independent weight configuration . We introduce the average output activation on the video portion between time instants and ,\n\n P(ω,t1,t2)≡∫t2t1¯¯¯¯P(ω,t)dt:=∫t2t1∫Rp(ω,x,u(t))μ(x,t)dxdt, (7)\n\nwhere is a spatio-temporal density and is the set of points that constitute the retina. The MI index over the video portion , is defined as\n\n I(X,Y;ω;t1,t2) = −H(Y|X;ω;t1,t2)+H(Y;ω;t1,t2) (8) = −m∑j=1∫t2t1∫Xpj(ω,x,u(t))logpj(ω,x,u(t))μ(x,t)dxdt+m∑j=1Pj(ω,t1,t2)logPj(ω,t1,t2)\n\nwhere is the entropy function, and and\n\nare random variables (\n\nis discrete) associated with the input333Since we are dealing with convolutional feature a realization of the random variable is specified by the coordinates of a point , the value of the temporal instant and the value of the video . and output space, respectively444When selecting a in base , the MI is in , that is what we will assume in the rest of the paper.. When no further information is available, is commonly assumed to be uniform in time and space and it is normalized such that .\n\nPerforming maximum-MI-based online learning of using the CALs in the time horizon is not straightforward. Once we restore the dependency of on time, by inserting in place of , we cannot simply plug (minus) the MI index as a potential loss in the Lagrangian due to the lack of temporal locality. As a matter of fact, in order to implement online learning dynamics, must be temporally local, i.e., it should depend on and at time only. For this reason, the authors of Betti et al. (2020b) compute the MI index at time , and not in an interval; the approximation of the MI in is yielded by the outer integration in the functional of Eq. (4) (or, equivalently, in the one of Eq. (2)). A drawback of this formulation is that, due to this temporal assumption, it could lead to a loose approximation of the original term of Eq. (8), for which the inner integration on time (Eq. (7)) is lost, and replaced by the outer integration of the functional. In order to better cope with the optimization dynamics, the two entropy terms are commonly weighted by positive scalars , . In addition to the plain-vanilla case we just described (referred to as PLA), we explore two other alternative criteria to mitigate the impact of time locality, that we will evaluate in Section 4. The first one (VAR) consists in introducing an additional auxiliary variable , that is used to replace of Eq. (7), while its variation, , is constrained to be almost equivalent to . The Lagrangian is augmented with , a soft-constraint that enforces to approximate the case in which the probability estimate is not limited to the current frame ().555Probabilistic normalization must be enforced after every update of . This idea is presented in Betti et al. (2020b) but not followed-up in any experimentation. As a second criterion (AVG), we propose to replace with the outcome of an averaging operation that keeps track of the past activation of the output units, i.e., , for two consecutive time instants .\n\n## 3 Focus of Attention\n\nThe way video data is commonly processed by machines usually lacks a key property of the human visual perception, that is the capability of exploiting eye movements to perform shifts in selective visual attention. High visual acuity is restricted to a small area in the center of the retina (fovea), and the purpose of the Focus Of Attention (FOA) is to selectively orient the gaze toward relevant areas with high information, filtering out irrelevant information from cluttered visual scenes McMains and Kastner (2009); Kowler (2010); Zanca et al. (2019). In the context of Section 2.2, we consider a visual stream and a neural architecture with output dimensions (per pixel), and we aim at developing the network weights such that the MI index is maximized as strongly as possible with respect to the model capacity. Of course, restricting the attention to a subset of the spatio-temporal coordinates of the video, due to a FOA mechanism, seems to inherently carry less information than when considering the whole video. However, in the latter case, the processed data will be characterized by a larger variability, mixing up noisy/background information with what could be more useful to understand the video. Such mixture of data could be harder to disentangle by a learning model than well-selected information coming from a human-like FOA trajectory, leading to a worse MI estimate. Curiously, the learning process restricted to the FOA trajectory could end-up in facilitating the development of the weights, so that the MI computed on the whole frame area could be larger than when learning without restrictions. Following the notation of Eq. (8), the MI maximization, for each , is based on the spatial distribution . Such distribution models the relevance of each coordinate when learning from frame . In Betti et al. (2020a, 2019), is assumed to be uniform over the frame area, while in Betti et al. (2020b) it is also described the idea of considering ( in Betti et al. (2020b)) as the most natural candidate for implementing a FOA-based mechanism. Let us assume that are the spatial coordinates of the FOA at time , then we define\n\n μ(x,t):=g(x−a(t)), (9)\n\nbeing a function that is peaked on . Following this parametrization of , we borrow a state-of-the art model for scanpath prediction defined in Zanca et al. (2019), that shares a physics-inspired formulation as CALs. Such FOA model has been proven to be strongly human-like in free-viewing conditions Zanca et al. (2020). It is based on the intuition that the attention emerges as a gravitational process, in which both low-level (gradient, contours, motion) or high-level features (objects, context) may act as gravitational masses. In particular, given the gravitational field , the law that drives the attention is\n\n ¨a(t)+ρ˙a(t)−E(t,a(t))=0, (10)\n\nthat is indeed another 2nd order model as the one we proposed in Section 2.1 (see Zanca et al. (2019) for more details). The dissipation is controlled by , and the importance of each mass can also be tuned. Interestingly, Eq. (10) describes the dynamics of the FOA, and it is not based on pre-computed or given saliency maps. In this paper, following Zanca et al. (2019), we consider two basic (low-level) perceptive features as masses, the spatial gradient of the brightness and the strength of the motion field. The trajectories simulated by the model show the same patterns of movement characteristic of human eyes: fixations, when the gaze remains still in a location of interest; saccades, rapid movement to reallocate attention on a new target; smooth pursuit, slow movements performed in the presence of a visual feedback with the purpose of tracking a stimulus.\n\nDifferent choices on are possible. In Section 4 we will consider the extreme case in which is a Dirac delta on the coordinates (we will refer to it as FOA), so that is essentially a mono-dimensional signal. A less extreme setting is the one in which is a squared window centered in that covers a small fraction of the frame (FOAW), while the most-relaxed setting is when is simply uniform on the whole frame (UNI), i.e., is not used.\n\n## 4 Experimental Results\n\nWe evaluated the amount of information transferred from different video streams with 2nd order laws of Section 2.1, using multiple instances of the deep convolutional network described in Section 2.2\n\nModels. Architectures are referred to as S (Small), D (Deeper), DL (Deeper and with a Larger number of neurons), and they are based on filters (except for the last layer – filters), (S) or (D, DL) layers, and either (S, D) or (DL) filters in layer . Networks S and D are composed of filters in each hidden layer, while DL has filters in each hidden layer. Following Section 3, we compared 3 potential terms based on 3 different input probability densities , named UNI, FOA, FOAW (uniform, foa-restricted, and foa-window-restricted, respectively – window edge is of the min frame dimension). For each of them, we tested the 3 criteria of Section 2.2 to extend the temporal locality, PLA, VAR, AVG (fully local, variable-based, average).\n\nSetting & Data. We considered three visual streams with frames each. The first frames are the ones on which learning is performed, integrating the CALs. Then, the developed weights are used to measure the MI index over the following frames, directly applying the MI formulation of Eq. (8), i.e., , that is what we report in the results of this section. For all the models, independently on the probability density used in their potentials, we measured the MI index using in the UNI, FOA, FOAW cases.",
null,
"Figure 1: Sample frames taken from the SparseMNIST, Carpark, Call streams, left-to-right.\n\nThis means that, for example, a model trained following the FOA trajectory is then evaluated in the 5k test frames either considering the whole frame area, the FOA trajectory, or the window-based FOA trajectory. The three streams (Fig. 1), have different properties. The first one, SparseMNIST, is composed of a static frame () in which 10 digits from the MNIST data are sparsely located over a dark background. The second video, Carpark, is taken from a fixed camera monitoring a car parking area in front of a building. The last video, Call, is a recording taken from a webcam during a video call. Videos are repeated until the target number of frames is reached. The last two videos are processed at pixels per frame, grayscale, frames per second.",
null,
"Figure 2: For each stream, we show (left) the areas mostly covered by FOA (blue: largest attention), and (right) the scatterplots of the fixation points, with hue denoting the magnitude of the FOA velocity (blue: slower; yellow: faster). Low-speed movements happen on the most informative areas (e.g., digits, busy roads, human presence/movement, respectively).\n\nParameters. The FOA trajectory was generated by weighing the two gravitational masses (frame details) and (motion), respectively, and adjusting in order to adapt it to the each video. We analyze the behaviour of the FOA trajectories in Fig. 2. After a first experimentation in which we qualitatively observed the behaviour of the 2nd order laws, we set , , . For each model we considered multiple weighing schemes of the parameters , , , , selecting the ones that returned the largest MI. As a general rule of thumb, using a lower value of the conditional entropy weighing term w.r.t. the entropy weight , helps the model to exploit all the available output symbols. The network weights were randomly initialized, enforcing the same initialization to all the compared model.\n\nMain result. Our main results are highlighted in Tab. 1.\n\nEach column, starting from the third one, is about a model, defined by the pair (architecture, density used in the training potential). For each model, the MI index is reported when measured using different spatio-temporal densities (they are labeled in column “Test”). We used the temporal locality criterion that led to the best results. Overall, the models trained on FOA-based densities (columns FOA, FOAW) usually perform better than the ones that were exposed to a uniform over the frame area (columns UNI). This is particularly noticeable in the SparseMNIST and Call streams, characterized by a still and not-much-detailed background and few regions of interest, i.e. the digits or the moving speaker, respectively. The filtering approach induced by the attention in the training stage highly improves the information transfer over most of the considered test measurements, with just a few exceptions. These considerations holds at a lesser degree also in the Carpark stream, in which frames are more detailed. The focus is attracted by a busy road or by people parking their cars. However, also the immediate surroundings of those regions contain much information, so that training with FOAW density achieves the best results in architectures D and DL, while the more extreme FOA approach do not compete with models trained considering the whole frame (UNI). In both the Carpark and Call streams, the S architecture does not benefit from learning over the attention trajectory. We motivate this result by considering that S is a shallower model, that inherently learns lower level features that the other ones. These features are more common to different frame location, making the impact of attention less evident. In the case of SparseMNIST, the dark-uniform background dominates the frame, and learning over induces a largest information transfer also in network S.\n\nTemporal locality. In order to evaluate the impact of the temporal locality criteria (PLA, AVG, VAR), we restrict our analysis to models trained with a FOA-restricted probability density. In this case, we describe each model by the pair (architecture, temporal locality criterion), and we report results in Tab. 2. In general, the moving average criterion (AVG) achieves the best performances in all settings, with some exceptions. The Carpark stream has temporal dynamics that are pretty repetitive and periodic (e.g., cars crossing the same crossroad etc.). Hence, the addition of a criterion to better keep track of the temporal information turns out to be less necessary. We notice higher value of MI index in the fully temporally local case (PLA) in architecture DL. This may be due to the fact that DL has a larger number parameters and units than the other nets, and it has intrinsically more capacity to memorize the temporal information. The MI index is lower that the one of the other architectures due to the largest size of the output space.\n\nRandom scanpaths. We are left with the open question on whether the largest information transfer we experienced is due to the state-of-the art attention model we used or it is only due the reduction of the size of the input data. We compared models trained on the FOA trajectories used so far with the same networks trained randomly sampling\n\nfrom a uniform distribution over the retina. The results of Fig.\n\n3 show that the human-like trajectory estimated by the selected attention model has a clear positive impact in the information transfer. Interestingly, in the Carpark case we sometimes observe that fixations which explore random coordinates highly foster information transfer. This confirms our previous statements regarding the large amount of information in whole the frame area.\n\nLearning dynamics. We investigate the behaviour of the models during the training stage, in the case of architecture D and a single training/test probability density, FOA. The plots of Fig. 4, for each value of the -axis, shows the MI index computed in the interval along the FOA trajectory, for different temporal criteria (PLA, AVG, VAR). The variable-based (VAR) model tends to quickly find a stationary condition of the estimated MI index value. Both PLA and AVG incur in an initial stage with evident fluctuations before becoming more stable, usually in larger values than VAR. The models have to deal with pretty varied conditions at the first stages of learning, which is limited to a single location in each frame. As long as time passes and a largest portion of stream is processed, fluctuations are mitigated reaching more stable configurations.",
null,
"Figure 3: Comparison between models trained on a regular trajectory of the attention and on a random trajectory (suffix -Rnd), for architectures S, D, DL. Each bar is about a different training probability density, and the height of the bar is the test MI index along the regular FOA trajectory.",
null,
"Figure 4: Learning dynamics (model D-FOA, different temporal criteria). The MI index is shown at different time instants. The index at time t is evaluated along the FOA trajectory in the interval [0,t].\n\n## 5 Conclusions and Future Work\n\nIn this work we delved into a novel approach to Mutual Information (MI) maximization rising from the conjunction of online entropy estimation mechanisms and human-like focus of attention. We introduced a 2nd order differential model, providing insightful experimental results to support the intuition that using the focus of attention to drive the learning dynamics fosters an increment of the globally transferred information from the input stream. Future work will be devoted to enforcing coherence over the predictions performed on the focus trajectory to develop high-level representations.\n\nOur work is a foundational study. We believe that there are neither ethical aspects nor future societal consequences that should be discussed.\n\nThis work was partly supported by the PRIN 2017 project RexLearn, funded by the Italian Ministry of Education, University and Research (grant no. 2017TWNMH2)\n\n## References\n\n• L. Ambrosio, G. Dal Maso, M. Forti, M. Miranda, and S. Spagnolo (2006) Ennio de giorgi-selected papers. Springer-Verlag. Cited by: §2.1.\n• M. I. Belghazi, A. Baratin, S. Rajeshwar, S. Ozair, Y. Bengio, A. Courville, and D. Hjelm (2018) Mutual information neural estimation. In International Conference on Machine Learning, pp. 531–540. Cited by: §1.\n• A. Betti, M. Gori, and S. Melacci (2020a) Cognitive action laws: the case of visual features. IEEE Transactions on Neural Networks and Learning Systems 31 (3), pp. 938–949. Cited by: §1, §1, §2.1, §2.2, §2, §2, §3, footnote 1.\n• A. Betti, M. Gori, and S. Melacci (2019) Motion invariance in visual environments. In\n\nProceedings of the Twenty-Eighth International Joint Conference on Artificial Intelligence, IJCAI-19\n\n,\npp. 2009–2015. External Links: Cited by: §1, §1, §2.2, §2, §3.\n• A. Betti, M. Gori, and S. Melacci (2020b) Learning visual features under motion invariance. Neural Networks 126, pp. 275 – 299. External Links: ISSN 0893-6080, Document Cited by: §1, §1, §1, §2.2, §2.2, §2, §3.\n• A. Borji and L. Itti (2012) State-of-the-art in visual attention modeling. IEEE transactions on pattern analysis and machine intelligence 35 (1), pp. 185–207. Cited by: §1.\n• D. Damen, H. Doughty, G. M. Farinella, S. Fidler, A. Furnari, E. Kazakos, D. Moltisanti, J. Munro, T. Perrett, W. Price, and M. Wray (2018) Scaling egocentric vision: the epic-kitchens dataset. In\n\nEuropean Conference on Computer Vision (ECCV)\n\n,\nCited by: §1.\n• M. Gori, M. Lippi, M. Maggini, and S. Melacci (2016) Semantic video labeling by developmental visual agents. Computer Vision and Image Understanding 146, pp. 9–26. Cited by: §2.2.\n• M. Gori, S. Melacci, M. Lippi, and M. Maggini (2012) Information theoretic learning for pixel-based visual agents. In Computer Vision – ECCV 2012, A. Fitzgibbon, S. Lazebnik, P. Perona, Y. Sato, and C. Schmid (Eds.), Berlin, Heidelberg, pp. 864–875. External Links: ISBN 978-3-642-33783-3 Cited by: §2.2.\n• R. D. Hjelm, A. Fedorov, S. Lavoie-Marchildon, K. Grewal, P. Bachman, A. Trischler, and Y. Bengio (2019) Learning deep representations by mutual information estimation and maximization. ICLR arXiv preprint arXiv:1808.06670. Cited by: §1.\n• W. Hu, T. Miyato, S. Tokui, E. Matsumoto, and M. Sugiyama (2017) Learning discrete representations via information maximizing self-augmented training. In Proceedings of the 34th International Conference on Machine Learning-Volume 70, pp. 1558–1567. Cited by: §1.\n• E. Kowler (2010) Attention and eye movements. In Encyclopedia of neuroscience, pp. 605–616. Cited by: §3.\n• A. Krizhevsky (2009) Learning multiple layers of features from tiny images. External Links: Link Cited by: §1.\n• M. Liero and U. Stefanelli (2013) A new minimum principle for lagrangian mechanics. Journal of nonlinear science 23 (2), pp. 179–204. Cited by: §2.1.\n• S. A. McMains and S. Kastner (2009) Visual attention. In Encyclopedia of Neuroscience, M. D. Binder, N. Hirokawa, and U. Windhorst (Eds.), pp. 4296–4302. External Links: ISBN 978-3-540-29678-2, Document, Link Cited by: §3.\n• S. Melacci and M. Gori (2012) Unsupervised learning by minimal entropy encoding. IEEE transactions on neural networks and learning systems 23 (12), pp. 1849–1861. Cited by: §1.\n• V. Mnih, N. Heess, A. Graves, and k. kavukcuoglu (2014) Recurrent models of visual attention. In Advances in Neural Information Processing Systems 27, Z. Ghahramani, M. Welling, C. Cortes, N. D. Lawrence, and K. Q. Weinberger (Eds.), pp. 2204–2212. External Links: Link Cited by: §1.\n• A. v. d. Oord, Y. Li, and O. Vinyals (2018) Representation learning with contrastive predictive coding. arXiv preprint arXiv:1807.03748. Cited by: §1.\n• O. Russakovsky, J. Deng, H. Su, J. Krause, S. Satheesh, S. Ma, Z. Huang, A. Karpathy, A. Khosla, M. Bernstein, A. C. Berg, and L. Fei-Fei (2015) ImageNet Large Scale Visual Recognition Challenge. International Journal of Computer Vision (IJCV) 115 (3), pp. 211–252. External Links: Document Cited by: §1.\n• A. M. Saxe, Y. Bansal, J. Dapello, M. Advani, A. Kolchinsky, B. D. Tracey, and D. D. Cox (2019)\n\nOn the information bottleneck theory of deep learning\n\n.\nJournal of Statistical Mechanics: Theory and Experiment 2019 (12), pp. 124020. Cited by: §1.\n• E. Serra and P. Tilli (2012) Nonlinear wave equations as limits of convex minimization problems: proof of a conjecture by de giorgi. Annals of Mathematics, pp. 1551–1574. Cited by: Appendix A, Appendix A, §2.1.\n• R. Shwartz-Ziv and N. Tishby (2017) Opening the black box of deep neural networks via information. arXiv preprint arXiv:1703.00810. Cited by: §1.\n• U. Stefanelli (2011) The de giorgi conjecture on elliptic regularization. Mathematical Models and Methods in Applied Sciences 21 (6), pp. 1377Ą1394. Cited by: §2.1.\n• Y. Tian, D. Krishnan, and P. Isola (2019) Contrastive multiview coding. arXiv preprint arXiv:1906.05849. Cited by: §1.\n• N. Tishby and N. Zaslavsky (2015) Deep learning and the information bottleneck principle. In 2015 IEEE Information Theory Workshop (ITW), Vol. , pp. 1–5. Cited by: §1.\n• M. Tschannen, J. Djolonga, P. K. Rubenstein, S. Gelly, and M. Lucic (2020) On mutual information maximization for representation learning. ICRL arXiv preprint arXiv:1907.13625. Cited by: §1.\n• T. Xiao, Y. Xu, K. Yang, J. Zhang, Y. Peng, and Z. Zhang (2015)\n\nThe application of two-level attention models in deep convolutional neural network for fine-grained image classification\n\n.\nIn\n\nThe IEEE Conference on Computer Vision and Pattern Recognition (CVPR)\n\n,\nCited by: §1.\n• D. Zanca and M. Gori (2017) Variational laws of visual attention for dynamic scenes. In Advances in Neural Information Processing Systems 30, I. Guyon, U. V. Luxburg, S. Bengio, H. Wallach, R. Fergus, S. Vishwanathan, and R. Garnett (Eds.), pp. 3823–3832. External Links: Link Cited by: §1.\n• D. Zanca, S. Melacci, and M. Gori (2019) Gravitational laws of focus of attention. IEEE transactions on pattern analysis and machine intelligence. Cited by: §1, §1, §3.\n• D. Zanca, S. Melacci, and M. Gori (2020) Toward improving the evaluation of visual attention models: a crowdsourcing approach. CoRR abs/2002.04407. External Links: Link, 2002.04407 Cited by: §3.\n• R. Zhang (2019)\n\nAttention guided imitation learning and reinforcement learning\n\n.\nIn Proceedings of the AAAI Conference on Artificial Intelligence, Vol. 33, pp. 9906–9907. Cited by: §1.\n\n## Appendix A Proof of Theorem 1\n\nIn order to prove Theorem 1 we first describe a technical hypothesis on the potential . In detail, for all positive there exists two positive integrable functions and such that for every and for all we have\n\n |∇U(z,t)|≤δ(U(z,t)+|z|2)+cδ(t),|∂tU(z,t)|≤δ(U(z,t)+|z|2)+κδ(t) . (1)\n\nNotice that here, in order to simplify the notation, we use the same symbol for and for . We will also denote with the solution of problem (5).\n\nAs it is also remarked below the proof articulates as follow: first of all we asses the convergence of by compactness arguments, basically by performing an estimate on the solution ; then the uniform estimate on the norm of is used to check that the limit actually solves the problem (6).\n\n###### Proof.\n\nThe proof of this theorem follows the spirit of Theorem 4.2 of Serra and Tilli (2012). We will start with an uniform (in ) estimate of and then we will use this estimate in weak form of the Euler equation to show the convergence of to the solution of (6). We will prove the theorem in the case and .\n\nUniform Estimate. Start form the differential equation in (5) and scalar multiply it by :\n\n ε2αw(4)ε⋅(w′ε−w1)−2εαw(3)⋅(w′ε−w1)+α¨w⋅(w′ε−w1)+∇U⋅(w′ε−w1)=0,\n\nthen integrate this equation on the interval , and using the boundary conditions (5) integrate by parts to obtain\n\n ε2αw(3)ε(t)⋅(w′ε−w1)−ε2α2|¨wε(t)|2+ε2α2|¨wε(0)|2 − 2εαw(3)ε(t)⋅(˙wε(t)−w1)+2εα∫t0|˙wε(s)|2ds+α2|˙wε(t)−w1|2 + U(wε(t),t)−U(w0,0)−∫t0∇U(wε(s),s)⋅w1ds−∫t0∂tU(wε(s),s)ds.\n\nNow let us integrate this equality again in the interval , therefore obtaining\n\n (2ε−32ε2)∫T0α|¨wε(s)|ds+ε2(1+T)2α|¨wε(0)|+(12−ε)α|˙wε(T)−w1|2 + 2εα∫T0∫τ0¨wε(s)dsdτ+α2∫T0|˙wε(s)−w1|2ds+U(wε(T),T) + ∫T0U(wε(s),s)ds=∫T0∇U(wε(s),s)⋅w1+∫T0∫τ0∇U(wε(s),s)⋅w1dsdτ + (1+T)U(w0,0)+∫T0∫τ0∂tU(wε(s),s)dsdτ.\n\nNow we can take all the positive (for small enough) terms to the right hand side to obtain\n\n α2∫T0|˙wε−w1|2dt+∫T0U(wε(t),t)dt≤ (1+T)U(w0,0) +(1+T)|w1|∫T0|∇U(wε(t),t)|dt +T∫T0|∂tU(wε(t),t)|dt.\n\nNow using Eq. (1) we can choose to further reduce this inequality down to\n\n α2∫T0|˙wε−w1|2dt+∫T0U(wε(t),t)dt≤c(T)+C(T)∫T0|wε(t)|2dt, (2)\n\nwhere and are constant with respect to the parameter . Using Peter-Paul inequality we have that for all . Similarly since , we can write and using Peter-Paul and Cauchy-Schwartz we also end up with the estimate for all , which implies\n\n ∫T0|wε(t)|2dt≤T1/η−11−η|w0|2+T21−η∫T0|˙wε(t)|2dt. (3)\n\nPutting together Eq. (2) and (3) we finally obtain the wanted uniform bound , where is a constant with respect to the parameter .\n\nConvergence. Once we have this uniform bound we can complete the proof by arguing along the very same lines of the proof of Section 3.2 of Serra and Tilli (2012) to obtain the thesis. ∎"
] | [
null,
"https://deepai.org/static/images/logo.png",
null,
"https://deepai.org/publication/None",
null,
"https://deepai.org/publication/None",
null,
"https://deepai.org/publication/None",
null,
"https://deepai.org/publication/None",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.90991557,"math_prob":0.93123615,"size":33992,"snap":"2021-43-2021-49","text_gpt3_token_len":7642,"char_repetition_ratio":0.14010827,"word_repetition_ratio":0.015824491,"special_character_ratio":0.23917392,"punctuation_ratio":0.12932605,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.96846735,"pos_list":[0,1,2,3,4,5,6,7,8,9,10],"im_url_duplicate_count":[null,null,null,null,null,null,null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-10-21T00:20:09Z\",\"WARC-Record-ID\":\"<urn:uuid:457a7fa1-1eb3-4263-8238-1bde2aecf6ef>\",\"Content-Length\":\"765491\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:52f69961-ee29-4cf1-a86c-0307bfedcef0>\",\"WARC-Concurrent-To\":\"<urn:uuid:17d2cc34-8bc2-4394-8509-15ab0548a7b5>\",\"WARC-IP-Address\":\"52.26.170.65\",\"WARC-Target-URI\":\"https://deepai.org/publication/focus-of-attention-improves-information-transfer-in-visual-features\",\"WARC-Payload-Digest\":\"sha1:7H3JCSQKMKSD3HKBDC5WJXTECZ5YPGZE\",\"WARC-Block-Digest\":\"sha1:3LGQN2UNQJJOX2QD62O6TBWHKHZSV75H\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-43/CC-MAIN-2021-43_segments_1634323585353.52_warc_CC-MAIN-20211020214358-20211021004358-00185.warc.gz\"}"} |
http://unexpected.js.org/assertions/array-like/to-have-items-satisfying/ | [
"to have items satisfying\n\n• <array-like> to have items [exhaustively] satisfying <assertion>\n• <array-like> to have items [exhaustively] satisfying <any>\n\nAsserts that all items of an array (or array-like object) satisfy a given assertion or function.\n\nAlias: `to be an array whose items satisfy`.\n\nNotice this assertion fails when given an empty array.\n\nexpect(\n[0, 1, 2, 3, 4],\n'to have items satisfying',\nexpect.it(function(item) {\nexpect(item, 'to be a number');\n})\n);\n\nexpect([0, 1, 2, 3, 4], 'to have items satisfying', 'to be a number');\n\nexpect(\n[, ],\n'to have items satisfying',\n'to have items satisfying',\n'to be a number'\n);\n\nexpect(\n[1, 2, 3, 4],\n'to have items satisfying',\nexpect.it('to be a number').and('to be positive')\n);\n\nIn case of a failing expectation you get the following output:\n\nexpect(\n[[0, 1, 2], [4, '5', '6'], [7, '8', 9]],\n'to have items satisfying',\n'to have items satisfying',\n'to be a number'\n);\nexpected array to have items satisfying to have items satisfying to be a number\n\n[\n\n012 ],\n\n[\n\n4,\n\n'5'\n//\n\nshould be a number\n\n'6'\n//\n\nshould be a number\n],\n\n[\n\n7,\n\n'8'\n//\n\nshould be a number\n\n9\n]\n]\n\nHere a another example:\n\nexpect(\n[0, 1, 2, 3, 4],\n'to have items satisfying',\nexpect.it('to be a number').and('to be positive')\n);\nexpected [ 01234 ] to have items satisfying\nexpect.it('to be a number')\n.and('to be positive')\n\n[\n\n0\n//\n//\n\n✓\nshould be a number\nand\n⨯\nshould be positive\n\n1,\n\n2,\n\n3,\n\n4\n]"
] | [
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.6775036,"math_prob":0.94347346,"size":1421,"snap":"2019-26-2019-30","text_gpt3_token_len":446,"char_repetition_ratio":0.24417783,"word_repetition_ratio":0.256917,"special_character_ratio":0.3687544,"punctuation_ratio":0.23291926,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9550566,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-06-19T10:55:13Z\",\"WARC-Record-ID\":\"<urn:uuid:12a30033-612a-45b6-b9f7-c41f6cbbb7ae>\",\"Content-Length\":\"26359\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:ae47a326-30ac-449d-b424-458d79ebcf42>\",\"WARC-Concurrent-To\":\"<urn:uuid:976a8512-8d0c-4c21-9b6e-9a6cb1ba2bb3>\",\"WARC-IP-Address\":\"185.199.110.153\",\"WARC-Target-URI\":\"http://unexpected.js.org/assertions/array-like/to-have-items-satisfying/\",\"WARC-Payload-Digest\":\"sha1:EP27I3KJMCHRBYL4SGOUHGFNUH3UAHHW\",\"WARC-Block-Digest\":\"sha1:WTS3I4OFPD5VKRC33OMFDOHNCYW3B3TY\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-26/CC-MAIN-2019-26_segments_1560627998959.46_warc_CC-MAIN-20190619103826-20190619125826-00214.warc.gz\"}"} |
http://www.euclideanspace.com/maths/topology/algtop/index.htm | [
"# Algebraic Topology\n\nAlgebraic topology turns topology problems into algebra problems.\n\nAs discussed on an earlier page, in two dimensions it is relatively easy to determine if two spaces are topologically equivalent (homeomorphic). We can check if they:\n\n• are connected in the same way.\n• have the same number of holes.\n\nHowever, when we scale up to higher dimensions this does not work and it can become impossible to determine homeomorphism. There are methods which will, at least, allow us to prove more formally when topological objects are not homeomorphic.\n\nThese methods use 'invariants': properties of topological objects which do not change when going through a homeomorphism.\n\n An important invariant is the number of 'holes' in each dimension.",
null,
"Here there is one hole, any homeomorphic transformation will still have one hole. Dually we could look at the maximum number of n-dimensional cuts we can make without dividing into two. This is really the same thing since each cut removes a hole.",
null,
"This cut does not divide the shape into two parts because we can still go round the other way.\n\nIf the above invariants are the same it is a good indication that the shapes are homeomorphic but it is not enough, other factors like 'torsion' also need to be unchanged to be sure.\n\nHere we look at two types of invariants which arise from homotopy and homology. (I have written some code to implement these structures on the page here)\n\nThese invariants can be expressed as algebraic structures, particularly groups, so this subject is called 'algebraic topology'. The way that these algebraic structures arise is discussed on the homotopy and homology pages but first we need to introduce a way to specify topological objects in a way that we can calculate with. We will do this by using simplicial complexes.\n\n### Equivalance Classes\n\nEquivalance classes exist when we have classes we wish to consider essentially the same.\n\nExamples:\n\n• A set of objects with the same shape.\n• The set of integers with the same remainder when divided by a given number.\n\nSo we can start to get the idea that this is related to the concept of quotient.\n\nAn equivalence relation has the following properties:\n\n• reflexive\n• symmetric\n• transitive\n\nSee partial order for more.\n\n### Homotopy and Homology Equivalance\n\nIn the homotopy case we have path components of X written π(X)",
null,
"We have a continuous map from space X to space Y: f: X -> Y and a continuous map from space Y to space X: g: Y -> X\nHomotopy Homomorphism\n\nA homotopy equivalence is where the composition:\n\ng o f: X -> X\n\nis homotopic to the identity map on X\n\nand simlarly for:\n\nf o g: Y -> Y\n\nA homomorphism is where the composition:\n\ng o f: X -> X\n\nis equal to the identity map on X\n\nand simlarly for:\n\nf o g: Y -> Y\n\n## Homotopy\n\nA homotopy is a continuous mapping between two spaces. Often parameterised by 't' to be though of as time.\n\n## Homotopy Groups\n\nThe fundamental group of a pointed space (mostly represented here by simpectial complexes) is isomorphic to the fundamental group of the space (Seitert-Van Kampen theorem).\n\n We look at loops of maps from a point to the given space. Each loop, in the space, from the point back to itself is a generator for the group. These loops can then be composed. The homotopy group is is finitely presented by generators and relations. This representation of a group is not, in general, algorithmically computable into other representations of a group.",
null,
"The simplest homotopy group is the fundamental group. It determines when two paths, starting and ending the point, can be continuously deformed into each other. It records information about the shape in terms of holes in the topological space.",
null,
"nth homotopy group. Instead of mapping a circle onto our topological space we map a sphere or higher order sphere onto the space.",
null,
"To generate the fundamental group from the simplicial complex see the page here.\n\n## Homology\n\n When we looked at the delta complex we got a chain of 'face maps' between each dimension and the next lower one.",
null,
"In homology we treat this as a chain of abelian groups.\n\nMore detail on the page here.\n\n## Cell Complexes\n\n There are many ways to approach cell complexes. They originally arose from topology but they can also be used in a purely combinatorial context or an algebraic context. We can also look at them as a greneralisation of the structure of a graph.",
null,
"## Cell Complexes\n\n In a graph an edge has arrows to two vertices (the source and target). Simpectial complexes generalise this to allow any number of vertices.",
null,
"A 'simplex' is a set of vertices such that every subset is included in the simplex. For example a tetrahedron contains all its faces and lines.\n\nA 'simplicial complex' is a set of these simplexes which may have vertices in common.\n\n### Next Steps\n\n• The additional tests for a geometric simplicial complex are described on the page here.\n• The way we implement topological aspects of simplicial complexes such as boundaries and cycles is explained on the page here.\n• To generate the fundamental group from the simplicial complex see the page here.\n• Products are quite complicated so I have put this on a separate page here.\n\n### Bibliography\n\nFor more details see:\n\n• Mathematics++ Kantor,Matousek,Samal 2015 ISBN 978-1-4704-2261-5 Chapter 6 - Topology. Contains a relatively gentle introduction to homology.\n• Graphs, Surfaces and Homology, Peter Giblin 2010 ISBN 987-0-521-15405-5\nBuilds up to homology groups via graphs and simplicial complexes.\n• Wikipedia\n• How to compute this stuff\n• Hatcher - Algebraic Topology - book also available free online.\n\nOther Sites"
] | [
null,
"http://www.euclideanspace.com/maths/topology/algtop/oneHole.png",
null,
"http://www.euclideanspace.com/maths/topology/algtop/oneCut.png",
null,
"http://www.euclideanspace.com/maths/topology/algtop/equivalence.png",
null,
"http://www.euclideanspace.com/prog/scratchpad/mycode/topology/torus.png",
null,
"http://www.euclideanspace.com/maths/topology/algtop/homotopy/fundamentalGroup.png",
null,
"http://www.euclideanspace.com/maths/topology/algtop/homotopy/nthHomotopyGroup.png",
null,
"http://www.euclideanspace.com/maths/topology/algtop/homology/homologyFaceMaps.png",
null,
"http://www.euclideanspace.com/prog/scratchpad/mycode/topology/graphCategory.png",
null,
"http://www.euclideanspace.com/prog/scratchpad/mycode/topology/simplecticalComplexCategory.png",
null
] | {"ft_lang_label":"__label__en","ft_lang_prob":0.89639914,"math_prob":0.92531115,"size":5588,"snap":"2021-31-2021-39","text_gpt3_token_len":1289,"char_repetition_ratio":0.11389685,"word_repetition_ratio":0.062240664,"special_character_ratio":0.21385111,"punctuation_ratio":0.08766859,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9944984,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18],"im_url_duplicate_count":[null,4,null,4,null,4,null,6,null,9,null,9,null,null,null,4,null,5,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-09-28T06:39:38Z\",\"WARC-Record-ID\":\"<urn:uuid:e682f7ad-2fb0-4dbd-84d6-cd696111a5e8>\",\"Content-Length\":\"26538\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:b8e8d461-a5f1-4b85-a010-09e0f2f12bbb>\",\"WARC-Concurrent-To\":\"<urn:uuid:c4ba0a04-6d3c-466b-9873-64eddcbea0de>\",\"WARC-IP-Address\":\"217.160.0.191\",\"WARC-Target-URI\":\"http://www.euclideanspace.com/maths/topology/algtop/index.htm\",\"WARC-Payload-Digest\":\"sha1:EFUER6QBHYJYBWR2NWDIFP6DEUC3UXMH\",\"WARC-Block-Digest\":\"sha1:NMGUEJFIA4UM6VOSTGJANUYBIC3AEA4M\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-39/CC-MAIN-2021-39_segments_1631780060538.11_warc_CC-MAIN-20210928062408-20210928092408-00383.warc.gz\"}"} |
http://kwiznet.com/p/takeQuiz.php?ChapterID=11609&CurriculumID=49&Num=4.9 | [
"kwizNET Subscribers, please login to turn off the Ads!\n Email us to get an instant 20% discount on highly effective K-12 Math & English kwizNET Programs!\n\n#### Online Quiz (WorksheetABCD)\n\nQuestions Per Quiz = 2 4 6 8 10\n\n### High School Mathematics - 24.9 Functions\n\n A function is a relation (usually an equation) in which no two ordered pairs have the same x-coordinate when graphed. One way to tell if a graph is a function is the vertical line test, which says if it is possible for a vertical line to meet a graph more than once, the graph is not a function. Functions are usually denoted by letters such as f or g. If the first coordinate of an ordered pair is represented by x, the second coordinate (the y coordinate) can be represented by f(x). When a function is an equation, the domain is the set of numbers that are replacements for x that give a value for f(x) that is on the graph. Example 1: For f(x) = 2x+6, find f(5) f(x) = 2x+6 = 2x5+6 = 10 + 6 = 16 Example 2: Find the domain of the function f(x) = 4/x x can take any value except zero. Since division by 0 is not defined. Therefore, the domain is said to be x > 0 and x < 0. Directions: Answer the following questions. Also write at least 10 examples of your own.\n Q 1: For f(x) = 2x, find f(5x)8x10x5x Q 2: For x>3, if f(x) = 3x -2 , g(x) = x2-2, find f3(2x-1)(2x-1)3(3x-2) Q 3: State if f = {(1,2), (2,2), (3,2),(4,2)} is a function or not?NoYes Q 4: If f = {(1,2), (2,-3), (3,1)} is a function, find 2+f{(2,4), (3,4), (3,5)}{1,4), (2,-1), (3,1)}{(3,2),(4,-3), (5,1)} Q 5: If f is a real; function, find the domain of f(x) = 10-x1R0 Q 6: Given that f(x) = 2x and f: N->N, Check if f(2) + f(3) = f(2+3)noyes Q 7: For x>3, if f(x) = 3x -2 , g(x) = x2-2, find (3f - 2g)(x)-2x2-6x+3-2x+36x+2 Q 8: Let x = {2,3}, Y = {1,3,5}, ow many different functions are there from X into Y.795 Question 9: This question is available to subscribers only! Question 10: This question is available to subscribers only!\n\n#### Subscription to kwizNET Learning System offers the following benefits:\n\n• Unrestricted access to grade appropriate lessons, quizzes, & printable worksheets\n• Instant scoring of online quizzes\n• Progress tracking and award certificates to keep your student motivated\n• Unlimited practice with auto-generated 'WIZ MATH' quizzes\n• Child-friendly website with no advertisements\n• Choice of Math, English, Science, & Social Studies Curriculums\n• Excellent value for K-12 and ACT, SAT, & TOEFL Test Preparation\n• Get discount offers by sending an email to discounts@kwiznet.com\n\n Quiz Timer"
] | [
null
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https://mathoverflow.net/questions/219945/mod-p-cohomology-ring-of-alternating-groups | [
"# mod p cohomology ring of alternating groups\n\nLet $A_n$ be the alternating group of $\\{1,2,\\cdots,n\\}$.\n\n(1). What is the cohomology ring $$H^*(A_4;\\mathbb{Z}/3)$$ and its Steenrod operation $P^i$'s?\n\n(2). Are there general results about the cohomology ring $$H^*(A_{p+1};\\mathbb{Z}/p)$$ for general primes $p\\geq 3$?\n\n(3). What is the cohomology ring $$H^*(A_n;\\mathbb{Z}_2)$$ for $n\\geq 4$ (we can impose conditions on $n$)?\n\nAny references?\n\n• For odd prime $p$, he $p$-sylow subgroup of $A_{p+1}$ is $Z/p$, so they are a direct summand of $H^*(BZ/p.Z/p)$. It shouldn't be too hard to determine. – user43326 Oct 4 '15 at 6:34\n• Alternating groups have homological stability, and the stable homology is computable via scanning, eg arxiv.org/abs/1306.6896. – skupers Oct 4 '15 at 15:05\n• @skupers OP is asking for the homology of individual $A_m$. – user43326 Oct 5 '15 at 8:05\n\nAn easier way for the first case\n\nConsider $P$, a $3$-Sylow subgroup of $A_4$. For example, take the cyclic group generated by the cyclic permutation (123). It is self normalizing, so the double coset formula for the compositions $BP\\rightarrow BA_4 \\stackrel{tr}{\\rightarrow}BP$ where $tr$ denotes the transfer, reduces to the identity. Therefore $BP$ and $BA_4$ are homotopy equivalent at the prime 3.\n\nFor the second case, let's start with the review of the well-known computation of $H^*(B\\Sigma _p;Z/p)$. Again as in the above, denote by $P$ the cyclic group generated by the cyclic permutation $(12\\cdots p)$. Denote by $N$ the group of affine automorphisms of $Z/p$, considered as a subgroup of the permutation of $\\{1,\\ldots ,p\\}$. Then $N$ is the normalizer of $P$ in $\\Sigma _p$, with $N/P\\cong Gl_1(Z/p)$ with the canonical action on $Z/p$. Now the double coset formula for the compositions $BP\\stackrel{Bi}{\\rightarrow} B\\Sigma _p \\stackrel{tr}{\\rightarrow}BP$ says that in mod $p$ cohomology, this composition is the sum of maps induced by the multiplication by $s\\in Gl_1(Z/p)$. In other words, we have, $$Bi^*tr^*(\\beta ^{\\epsilon}x^i)=\\Sigma _{s\\in Gl_1(Z/p)}\\beta ^{\\epsilon}s^ix^i\\in H^*(BZ/p,Z/p)\\cong Z/p[x]\\otimes \\Lambda _{Z/p}(\\beta x).$$ The little Theorem of Fermat then shows that this is identity if $p-1\\mid i$, $0$ otherwise. Therefore we get $$H^*(B\\Sigma _p,Z/p)\\cong Z/p[x^{p-1}]\\otimes \\Lambda _{Z/p}(\\beta x^{p-1})\\subset H^*(BZ/p,Z/p).$$\n\nNow, if we replace $\\Sigma _p$ with $A_{p+1}$, what changes is the normalizer. It is easy to see that $$N_{A_{p+1}}(P)=A_{p+1}\\cap \\Sigma _p.$$ We also see that the generator of $Gl_1(Z/p)$ acts on $P$ as a cyclic permutation of length $p-1$, thus its an odd permutation. This means in the appropriate double coset formula, the only half of $s's$ get involved (squares in $Gl_1(Z/p)$), and we arrive at the conclusion $$H^*(BA _{p+1},Z/p)\\cong Z/p[x^\\frac{p-1}{2}]\\otimes \\Lambda _{Z/p}(\\beta x^\\frac{p-1}{2})\\subset H^*(BZ/p,Z/p).$$ When $p=3$, this reduces to the first case treated in the above.\n\nRegarding your first question, you have a group extension $$1\\rightarrow (\\mathbb{Z}/2)^2\\rightarrow A_4\\rightarrow \\mathbb{Z}/3\\rightarrow 1.$$ Then we can use the Lyndon-Hochschild-Serre spectral sequence $$E_2^{p,q}=H^p(\\mathbb{Z}/3,H^q((\\mathbb{Z}/2)^2,\\mathbb{Z}/3))\\implies H^{p+q}(A_4,\\mathbb{Z}/3)$$ a priori the $E_2$-page involves local coefficient cohomology. But what you get, by triviality of $H^q((\\mathbb{Z}/2)^2,\\mathbb{Z}/3)$ is that the projection map $A_4\\rightarrow \\mathbb{Z}/3$ induces an isomorphism of unstable $\\mathcal{A}_3$-algebra: $$H^{*}(A_4,\\mathbb{Z}/3)\\cong H^{*}(\\mathbb{Z}/3,\\mathbb{Z}/3).$$ And $H^*(\\mathbb{Z}/3,\\mathbb{Z}/3)$ is isomorphic to the tensor algebra $\\Lambda(x)\\otimes \\mathbb{Z}/3[y]$ where $x$ of degree 1 and $y$ of degree $2$ moreover $y=\\beta(x)$.\n\nAnd you can also use the same spectral sequence to compute $H^*(A_4,\\mathbb{Z}/2)$. What you get is an isomorphism of algebras $$H^*(A_4,\\mathbb{Z}/2)\\cong H^0(\\mathbb{Z}/3,H^*((\\mathbb{Z}/2)^2,\\mathbb{Z}/2))\\cong \\mathbb{Z}/2[u,v]^{\\mathbb{Z}/3}$$ where $u$ and $v$ are of degree 1.\n\nEDIT: If you want to compute the cohomology algebra of $H^*(\\mathbb{Z}/3,\\mathbb{Z}/3)$. You can use the fact that $$B\\mathbb{Z}/3\\simeq L(\\infty,3)$$ where $L(\\infty,3)=\\bigcup_n L(n,3)$ is a limit of Lens spaces. And then use the fibration $$S^1\\rightarrow L(\\infty,3)\\rightarrow \\mathbb{C}P^{\\infty}.$$ Playing with the spectral sequence of this fibration you get the claimed results: $$H^*(\\mathbb{Z}/3,\\mathbb{Z}/3)\\cong H^*(S^1,\\mathbb{Z}/3)\\otimes H^*(\\mathbb{C}P^{\\infty},\\mathbb{Z}/3)\\cong \\Lambda(x)\\otimes \\mathbb{Z}/3[y].$$ In order to compute $\\beta(x)$,just look at this spectral sequence over the integers and observe that the differential $$E_2^{0,1}=\\mathbb{Z}\\langle x \\rangle\\rightarrow E_2^{2,0}=\\mathbb{Z}\\langle y \\rangle$$ is such that $dx=3y$. Now the action of $\\mathcal{A}_3$ is completely determined by the Cartan relation and the fact that:\n\n• $P^k(x)$ when $k>0$ by unstability,\n• $P^1(y)=y^3$ (because $y$ is of degree 2) and $P^k(y)=0$ when $k>1$."
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.7694734,"math_prob":0.9999683,"size":2069,"snap":"2019-13-2019-22","text_gpt3_token_len":691,"char_repetition_ratio":0.10992736,"word_repetition_ratio":0.048109967,"special_character_ratio":0.32334462,"punctuation_ratio":0.09471366,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":1.0000069,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-03-18T16:38:09Z\",\"WARC-Record-ID\":\"<urn:uuid:596c163b-ad69-483d-9adf-244dfd303f10>\",\"Content-Length\":\"124172\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:299bfd0c-5342-4de5-9ab8-88d83f40e46d>\",\"WARC-Concurrent-To\":\"<urn:uuid:4e19c907-3e09-4a32-9c5a-82ff214ac1e6>\",\"WARC-IP-Address\":\"151.101.129.69\",\"WARC-Target-URI\":\"https://mathoverflow.net/questions/219945/mod-p-cohomology-ring-of-alternating-groups\",\"WARC-Payload-Digest\":\"sha1:Z7UFLAM23LJZBFDJXO7INWDNWTK2A26B\",\"WARC-Block-Digest\":\"sha1:JZCTDMGETYSWLSYUXZTZEBOPOQUWFFIM\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-13/CC-MAIN-2019-13_segments_1552912201455.20_warc_CC-MAIN-20190318152343-20190318174343-00167.warc.gz\"}"} |
https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-28-25-37249&id=443946 | [
"## Abstract\n\nFor the ill-posed inverse problem of LII-based nanoparticle size measurement, recovered primary particle size distribution (PPSD) is sensitive to the uncertainty of LII model parameters. In the absence of reliable prior knowledge, the thermal accommodation coefficient (TAC) and fractal-dependent shielding factor are often required to be inferred simultaneously with the PPSD. In the simplified LII model for low fluence regime, TAC and fractal-dependent shielding factor are combined to define a new fractal-dependent TAC. The present study theoretically verified the feasibility of inferring PPSD and fractal-dependent TAC from the normalized LII signals. Moreover, the inversion is independent of prior knowledge of most full LII model parameters, which is attributed to low laser fluence, normalized signal, and fractal-dependent TAC.\n\n© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement\n\n## 1. Introduction\n\nPrimary particle size distribution (PPSD) soot aggregate is an important property for human health and global climate modeling [1,2]. Laser-induced incandescence (LII) has developed as a powerful tool for estimating volume fraction, mean primary particle size, and PPSD of soot aggregate [3,4]. Compared with sampling-based ex-situ methods such as transmission electron microscope (TEM), LII has the advantage of non-invasive measurement and is applicable for fast online in-situ measurement .\n\nTo date, there have been many studies on the determination of PPSD with time-resolved laser-induced incandescence (TiRe-LII) signals. Roth et al. presented an in situ method for inferring particle size distribution by fitting the intensity of TiRe-LII signals. Filippov et al. applied this method to determine the PPSD of various types of aerosols. Kock et al. demonstrated the capability of this method to obtain almost instantaneous soot PPSD in diesel engine combustion with rapidly varying conditions. Lehre et al. extended this method to simultaneously measure PPSD and gas temperature. Lehre et al. [9,10] used the effective particle temperature derived from the ratio of TiRe-LII signals measured at two wavelengths to obtain PPSD, and proved that it can be used to infer PPSD and flame temperature simultaneously. Liu et al. proposed a simple method to determine the soot PPSD by using the effective temperature in the non-sublimation regime. Danker et al. retrieved the soot PPSD from two different characteristic time intervals of TiRe-LII curve.\n\nThe above LII-based PPSD recovery studies are hampered by the ill-posed nature of inverse problem, such that the recovered PPSD is sensitive to the uncertainties in the LII model parameters . Under low fluence conditions, the accurate prior knowledge of the thermal accommodation coefficient (TAC or αT) is necessary for a reliable estimate of PPSD. Michelsen and Daun used extrapolation from low temperature data using and excitation probability and molecular dynamics, respectively, to predict TAC prior considering LII data. Added factors, such as the influence of soot composition and maturity on the TAC values, may further complicate inference. Uncertainties are often lowered by assuming that the PPSD is log normal, reducing the PPSD inference problem to one determining the geometric mean primary particle diameter, dp, g, and the geometric standard deviation, σd, g. Kock et al. demonstrated such a scheme, where ex-situ measurements were used to determine σd, g and the TAC and geometric mean diameter were inferred simultaneously from TiRe-LII signals. Sipkens et al. [13,19] later showed that inference of the TAC and particle size is restricted to the transition or high fluence regimes, as the structure of the problem (wherein the particle size and TAC appear as a product) make it nearly impossible to determine TAC and dp, g from a conduction-dominated temperature decay. On the other hand, the above studies are generally limited to cases where the thermal shielding effect caused by the fractal structure of aggregate is neglected. Bauer et al. revealed that the fractal parameters highly correlated with the PPSD parameters amplifying the uncertainties in the recovered PPSD, As such, to determine the influence of fractal-dependent shielding factor, it is necessary to obtain prior knowledge of fractal structure and polydisperse distribution of aggregate size to infer the remaining particle properties. Unfortunately, fractal structure and aggregate size vary with the soot generation conditions or environmental conditions, and it is difficult to obtain their accurate values without additional sampling-based measurements.\n\nIn the absence of reliable prior knowledge, TAC and fractal-dependent shielding factor are required to be inferred with PPSD simultaneously, but it will not generally be possible to infer these quantities independently. Instead, we define a new fractal-dependent TAC, which combines the overall impact of TAC and fractal-dependent shielding factor on the simplified LII model for low fluence regime. The purpose of this paper is to theoretically evaluate the capability of inferring the PPSD and fractal-dependent TAC of soot aggregates from normalized TiRe-LII signals. In order to avoid the common inverse crime (see Section 3) in theoretical evaluation, this study uses a full LII model to synthesize LII data for evaluation, while uses a simplified model of the low-fluence regime to perform the inversion process. Since the dependence of LII model on aggregate structure, aggregate size distribution, and thermal accommodation coefficient is completely represented by the new parameter αT, f (see Section 3), the inference of PPSD and αT, f does not require the prior information of these properties. In addition, the inference of PPSD and αT, f does not require the prior information of absorption function at the measurement wavelength, the apparent fraction volume, and the calibration parameter when normalized LII signal is used for inversion analysis.\n\nThis paper is structured as follows. Section 2 describes the fractal-based full LII model used for LII data simulation, the simplified LII model in the low-fluence regime for inverse problem analysis, and the definition of fractal-dependent TAC. Section 3 explains the inversion process. Section 4 evaluates the feasibility of inferring PPSD and fractal-dependent TAC from normalized TiRe-LII signals, and analyzes log contour of the objective function. Section 5 summarizes the main conclusions of this paper.\n\n## 2. Time-resolved laser-induced incandescence model\n\n#### 2.1 Full LII model\n\nLaser-induced incandescence (LII) involves the effect of laser heating on the soot structure, please see Ref. . These works have provided extensive high-resolution TEM images of the soot aggregates and primary particles under a wide range of combustion conditions with the laser heating. These works provide important experimental support for the current modeling of LII signals. The full LII model (i.e. forward model) typically involves solving energy and mass balance equations, which include the effects of various submodels (cf. Fig. 1) :\n\n$${\\dot{Q}_{\\textrm{int}}} = {\\dot{Q}_{\\textrm{abs}}} + {\\dot{Q}_{\\textrm{cond}}} + {\\dot{Q}_{\\textrm{rad}}} + {\\dot{Q}_{\\textrm{sub}}} + {\\dot{Q}_{\\textrm{therm}}} + {\\dot{Q}_{\\textrm{ox}}} + {\\dot{Q}_{\\textrm{ann}}}$$\n$$\\dot{M} = {\\dot{M}_{\\textrm{sub}}} + {\\dot{M}_{\\textrm{ox}}}$$\nwhere ${\\dot{Q}_{\\textrm{int}}}$, ${\\dot{Q}_{\\textrm{abs}}}$, ${\\dot{Q}_{\\textrm{cond}}}$, ${\\dot{Q}_{\\textrm{rad}}}$, ${\\dot{Q}_{\\textrm{sub}}}$, ${\\dot{Q}_{\\textrm{ox}}}$, and ${\\dot{Q}_{\\textrm{ann}}}$ present the change rate of particle energy caused by internal energy, absorption of laser energy, conduction, radiation, sublimation, thermionic emission, oxidation and annealing, respectively; $\\dot{M}$ is the change rate of particle mass, ${\\dot{M}_{\\textrm{sub}}}$ and ${\\dot{M}_{\\textrm{ox}}}$ denote the mass change rate caused by sublimation and oxidation, respectively.",
null,
"Fig. 1. Schematic of underlying heat and mass transfer processes involved in LII\n\nThe internal energy change rate of any aggregate is assumed to result from a sum over the primary particles making up the aggregates, such that :\n\n$${\\dot{Q}_{\\textrm{int}}} = {N_\\textrm{p}}{c_\\textrm{s}}{\\rho _\\textrm{s}}\\frac{\\pi }{6}d_\\textrm{p}^3\\frac{{\\textrm{d}T}}{{\\textrm{d}t}}$$\nwhere Np is the number of primary particle in a single soot aggregate; cs and ρs are respectively the specific heat and density of soot aggregate (taken as temperature-dependent in this study, cf. Reference ); dp and T are the primary particle diameter and mean temperature of a single soot aggregate, respectively; and t is time.\n\nThe laser energy absorption of a single soot aggregate is determined by its absorption cross-section Cabs :\n\n$${\\dot{Q}_{\\textrm{abs}}} = {N_\\textrm{p}}{C_{\\textrm{abs}}}E(t )= {N_\\textrm{p}}{C_{\\textrm{abs}}}Fq(t )$$\nwhere E(t) is the temporal irradiance profile of the laser; F is the laser fluence; q(t) is the laser temporal variation function and is a Gaussian distribution with a standard deviation σLaser = 3.3 ns , and the spatial distribution of the laser beam is set as uniform top hat distribution; Cabs is the absorption cross-section of a single soot aggregate can be approximated by Rayleigh-Debye-Gans fractal aggregate (RDG-PFA) scattering theory :\n$${C_{\\textrm{abs}}} = \\frac{{{\\pi ^2}d_\\textrm{p}^3E(m )}}{{{\\lambda _{\\textrm{inc}}}}}$$\nwhere λinc denotes the wavelength of the incident pulse laser; E (m) is the soot absorption function which is determined by spectral complex refractive index m. Here, λinc is 532 nm, and the corresponding E (m) is 0.3 .\n\nThe cooling terms in this model generally are prescribed in Ref. . Conduction plays an important role in this model (and the simplified low-fluence model), such that it receives more attention here. A relatively accurate Fuchs boundary sphere model is applied to calculate heat conduction :\n\n$${\\dot{Q}_{\\textrm{cond}}} ={-} \\pi {N_\\textrm{p}}d_\\textrm{p}^2{\\alpha _\\textrm{T}}\\frac{{{P_\\textrm{a}}}}{8}\\sqrt {\\frac{{8{R_\\textrm{m}}{T_\\delta }}}{{\\pi {W_\\textrm{a}}}}} \\left( {\\frac{{{\\gamma^ \\ast } + 1}}{{{\\gamma^ \\ast } - 1}}} \\right)\\left( {\\frac{T}{{{T_\\delta }}} - 1} \\right)$$\nwhere αT = 0.37 is the thermal accommodation coefficient ; Pa = 1 atm is the pressure of ambient air; Rm = 83.145 g·m3/(mol·K·s2) is the universal gas constant in effective mass units; subscript δ is the thickness of the boundary layer in the Fuchs approach; Tδ is the temperature in the limiting sphere; Wa = 28.74 g/mol is the molecular weight of air; γ* is the average value of the specific heat ratio. For a detailed description of this method, see Ref. .\n\nThe time-dependent particle temperature T(t) and the time-dependent primary particle diameter dp(t) can be obtained simultaneously by solving the system of differential equations. In this study, the coupled system of equations is solved by the fourth-order Runge-Kutta approach.\n\n#### 2.2 Fractal aggregate structure\n\nAs shown in Fig. 1(b), primary particles of soot aggregates are not isolated nanospheres but agglomerated in the form of fractal structure. For a soot aggregate containing Np primary particles, its fractal structure can be mathematically described by :\n\n$${N_\\textrm{p}} = {k_\\textrm{f}}{\\left( {\\frac{{2{R_\\textrm{g}}}}{{{d_\\textrm{p}}}}} \\right)^{{D_\\textrm{f}}}}$$\nwhere Np is the number of primary particles in a single aggregate; kf is the fractal prefactor; Df is the fractal dimension; Rg is the gyration radius, dp is the diameter of the primary particles.\n\nFilippov et al. showed that the shielding effect can cause heat conduction rates from primary particles within a single aggregate to be an order of magnitude lower than that for isolated nanospheres, depending on the particle size, fractal structure, thermal accommodation coefficient, and the current flow regime . To account for the shielding effect of soot aggregates, previous works [30,32] replaced the diameter in the conduction expression above with an effective diameter, Deff, of a single soot aggregate as follows :\n\n$${\\dot{Q}_{\\textrm{cond}}} ={-} \\pi D_{\\textrm{eff}}^2{\\alpha _\\textrm{T}}\\frac{{{P_\\textrm{a}}}}{8}\\sqrt {\\frac{{8{R_\\textrm{m}}{T_\\delta }}}{{\\pi {W_\\textrm{a}}}}} \\left( {\\frac{{{\\gamma^ \\ast } + 1}}{{{\\gamma^ \\ast } - 1}}} \\right)\\left( {\\frac{T}{{{T_\\delta }}} - 1} \\right)$$\n\nIn their studies, Deff was assumed to be the projected-area equivalent diameter for fractal aggregates. Based on Eq. (7), Filippov et al. and Liu et al. both proposed a heuristic fractal-like relationship to parametrically express Deff. Their studies have not been further tested, and the physical connection between the effective diameter, and the fractal structure of the soot aggregate is complicated . Given that, this study uses the shielding factor η to establish the implicit relationship between the shielding effect and specific geometric structure (including fractal structure and particle size) of the aggregate. The mathematical relationship between Deff and η is defined as follows :\n\n$$D_{\\textrm{eff}}^2({d_\\textrm{p}},\\textrm{ }{N_\\textrm{p}},\\textrm{ }{k_\\textrm{f}},\\textrm{ }{D_\\textrm{f}}) = d_\\textrm{p}^2{N_\\textrm{p}}\\eta ({{N_\\textrm{p}},\\textrm{ }{k_\\textrm{f}},\\textrm{ }{D_\\textrm{f}}} )$$\n\nThe value of η used to simulate LII signals is derived from the Eq. (9) and the heuristic fractal-like relationship in Ref. and . The two characteristic parameters kh and Dh in this relationship are determined by the quadratic function of αT in Ref. .\n\n#### 2.3 Simplified LII model and definition of fractal-dependent TAC\n\nWhile simulation data will be evaluated using the full LII model above, analysis (i.e., the inverse problem) will use a simplified model for the low-fluence regime (this avoids inverse crime [33,34]). In this case, the energy and mass changes caused by the thermal radiation, sublimation, oxidation, and annealing are negligible, such that the system is reduced to\n\n$${\\dot{Q}_{\\textrm{int}}} = {\\dot{Q}_{\\textrm{abs}}} + {\\dot{Q}_{\\textrm{cond}}}$$\nand the mass changes are neglected.\n\nFor the simplified LII model, substituting Eqs. (3), (4), (8) and (9) into Eq. (11) yields dT/dt:\n\n$$\\frac{{\\textrm{d}T}}{{\\textrm{d}t}} = \\frac{6}{{\\pi {c_\\textrm{s}}{\\rho _\\textrm{s}}d_\\textrm{p}^3}}\\left[ {\\underbrace{{{C_{\\textrm{abs}}}Fq(t )}}_{{\\textrm{Absorption}}} - \\underbrace{{\\pi d_\\textrm{p}^2\\eta {\\alpha_\\textrm{T}}\\frac{{{P_\\textrm{a}}}}{8}\\sqrt {\\frac{{8{R_\\textrm{m}}{T_\\delta }}}{{\\pi {W_\\textrm{a}}}}} \\left( {\\frac{{{\\gamma^ \\ast } + 1}}{{{\\gamma^ \\ast } - 1}}} \\right)\\left( {\\frac{T}{{{T_\\delta }}} - 1} \\right)}}_{{\\textrm{heat conduction}}}} \\right]$$\n\nIn Eq. (11), the TAC and fractal-dependent shielding factor appear as an isolated product. According to the findings of Ref. , it is generally impossible to simultaneously infer two parameters that appear as a product in an equation. Instead, these two quantities are combined to define a new fractal-dependent TAC as the product,\n\n$${\\alpha _{\\textrm{T, f}}} \\equiv \\eta \\cdot {\\alpha _\\textrm{T}}$$\n\nThe influence of aggregate structure on the simplified LII model can be fully quantified by η. After lumping η with αT, the influence of aggregate structure on the simplified LII model is completely represented by αT, f. Since η and αT is related to many factors , the prior value of αT, f tends to have large uncertainty. If the inversion of PPSD is carried out when αT, f is a prior model parameter, it is impossible obtain accurate estimate of PPSD because of the inherent deviation of prior value of αT, f. Therefore, αT, f and PPSD are simultaneously inferred in this study.\n\nAs more and more evidence shows that primary particle size is relatively constant within an aggregate and varies more significantly between aggregates [35,36], this study assumes that dp is constant in aggregates but obeys a narrow log-normal distribution between aggregates :\n\n$$p({{d_\\textrm{p}}} )= \\frac{1}{{{d_\\textrm{p}}\\sqrt {2\\pi } \\ln {\\sigma _{\\textrm{d, g }}}}}\\textrm{exp} \\left[ { - {{\\left( {\\frac{{\\ln {d_\\textrm{p}} - \\ln {d_{\\textrm{p, g}}}}}{{\\sqrt 2 \\ln {\\sigma_{\\textrm{d, g }}}}}} \\right)}^2}} \\right]$$\nwhere dp, g and σd, g are the geometric mean primary particle diameter and the geometric standard deviation for the distribution of dp, respectively. The integration limits in Eq. (13) are 5 nm and 100 nm with enough refinement, so the integration error is negligible. It should be noted that this study is based on the assumption that primary particle size is basically the same within aggregate. The influence of the relatively large primary particle size distribution within aggregate on this study is beyond the scope of this paper and needs further study.\n\nThe aggregate size generally varies between aggregates and follow a log-normal distribution of Np:\n\n$$p({{N_\\textrm{p}}} )= \\frac{1}{{{N_\\textrm{p}}\\sqrt {2\\pi } \\ln {\\sigma _{\\textrm{N, g }}}}}\\textrm{exp} \\left[ { - {{\\left( {\\frac{{\\ln {N_\\textrm{p}} - \\ln {N_{\\textrm{p, g}}}}}{{\\sqrt 2 \\ln {\\sigma_{\\textrm{N, g }}}}}} \\right)}^2}} \\right]$$\nwhere Np, g and σN, g are the geometric mean primary particle number per aggregate and the geometric standard deviation for the distribution of Np, respectively. The integration limits in Eq. (14) are 1 and 600 with enough refinement, so the integration error is negligible.\n\nThe time-resolved laser-induced incandescence (TiRe-LII) signal of a single primary particle in any aggregate can be calculated as follows :\n\n$${S_\\textrm{p}}({t,\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )= \\frac{{8{\\pi ^3}h{c^2}E(m )d_\\textrm{p}^3(t )}}{{\\lambda _{\\textrm{mea}}^6 \\cdot \\textrm{exp} [{hc/{\\lambda_{\\textrm{mea}}}{k_\\textrm{B}}T({t,\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )} ]- 1}}$$\nwhere h = 6.626×10−34 J·s is the Plank’s constant; c = 2.998×108 m/s is the speed of light; kB = 1.381×10−23 J/K is the Boltzmann constant; λmea is the measurement wavelength; the mean particle temperature T is related to the fractal-dependent TAC.\n\nFor an aggregate with Np primary particles, the TiRe-LII signal can be calculated as follows :\n\n$${S_{\\textrm{agg}}}({t,\\textrm{ }{N_\\textrm{p}},\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )= \\int {{N_\\textrm{p}}{S_\\textrm{p}}({t,\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )p({d_\\textrm{p}})\\textrm{d}{d_\\textrm{p}}}$$\n\nThe total TiRe-LII signal of N soot aggregates in the measurement volume can be calculated as follows :\n\n$${S_{\\textrm{LII}}}({t,\\textrm{ }{N_\\textrm{p}},\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )= {C_{\\textrm{exp} }}N\\int\\!\\! \\int{ {{N_\\textrm{p}}{S_\\textrm{p}}({t,\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )p({d_\\textrm{p}})} p({{N_\\textrm{p}}} )\\textrm{d}{d_\\textrm{p}}\\textrm{d}{N_\\textrm{p}}}$$\nwhere Cexp is a calibration parameter determined by experimental conditions, which is related to the detection geometry and collection efficiency of the detector.\n\nIn this study, the relative intensity of (normalized) TiRe-LII signal RSLII(t) is used as the input for the inverse problem, defined by the ratio of the absolute intensity and maximum value of the TiRe-LII signal :\n\n$$R{S_{\\textrm{LII}}}({t,\\textrm{ }{N_\\textrm{p}},\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )= \\frac{{\\int {\\int {{N_\\textrm{p}}{S_\\textrm{p}}({t,\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )p({d_\\textrm{p}})} p({{N_\\textrm{p}}} )\\textrm{d}{d_\\textrm{p}}\\textrm{d}{N_\\textrm{p}}} }}{{\\int {\\int {{N_\\textrm{p}}{S_\\textrm{p}}({{t_{\\max }},\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )p({d_\\textrm{p}})} p({{N_\\textrm{p}}} )\\textrm{d}{d_\\textrm{p}}\\textrm{d}{N_\\textrm{p}}} }}$$\nwhere tmax is the time when the SLII(t) signal reaches its maximum $S_{\\textrm{LII}}^{\\max }$.\n\nIt should be noted that even if Df, kf, and αT are constant for all aggregates, the fractal-dependent TAC, αT, f, may be constant within aggregates but varies with the polydispersity of Np between aggregates. So, we emphasized the dependence on αT, f in Eqs. (16)–(18) for different aggregates. According to Eqs. (10)–(12), if αT, f is inferred simultaneously with PPSD, temporal mean particle temperature T can be obtained in the simplified LII model without prior knowledge of fractal structure. However, according to Eqs. (15)–(18), prior information of fractal parameter Np is still required to simulate normalized TiRe-LII signals. In order to make the inversion process based on the simplified LII model independent of the prior information of the fractal structure, Eqs. (16)–(18) are restated below.\n\nFirst, Sagg(t) in Eq. (16) is assumed to be the product of an equivalent primary particle number per aggregate, Np, eff and the integral of Sp:\n\n$${S_{\\textrm{agg}}}(t )\\equiv {N_{\\textrm{p, eff}}}\\int {{S_\\textrm{p}}({t,\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )p({d_\\textrm{p}})\\textrm{d}{d_\\textrm{p}}}$$\nwhere Np, eff is constant for different aggregates.\n\nConsidering the definition of αT, f in Eq. (12), αT, f varies for different aggregates. But in order to obtain a constant parameter as the inverse problem variable, the definition of αT, f must be extended for all aggregates within the measurement volume. According to the final definition of αT, f, it considers the overall impact of TAC and fractal-dependent shielding factor of all aggregates on the simplified LII model. The target value of αT, f can be obtained by minimizing the difference between the LII signals generated by the full LII model and the simplified LII model when the other two variables (dp, g and σd, g) are fixed at their target values. In this study, the target value of αT, f is 0.26.\n\nBased on Eq. (19), Eq. (17) can be restated as:\n\n$${S_{\\textrm{LII}}}(t )= {C_{\\textrm{exp} }}N{N_{\\textrm{p, eff}}}\\int {{S_\\textrm{p}}({t,\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )p({d_\\textrm{p}})} \\textrm{d}{d_\\textrm{p}}$$\n\nThen, Eq. (18) is restated as follows\n\n$$R{S_{\\textrm{LII}}}(t )= \\frac{{{C_{\\textrm{exp} }}N{N_{\\textrm{p, eff}}}\\int {{S_\\textrm{p}}({t,\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )p({d_\\textrm{p}})} \\textrm{d}{d_\\textrm{p}}}}{{{C_{\\textrm{exp} }}N{N_{\\textrm{p, eff}}}\\int {{S_\\textrm{p}}({{t_{\\max }},\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )p({d_\\textrm{p}})} \\textrm{d}{d_\\textrm{p}}}} = \\frac{{\\int {{S_\\textrm{p}}({t,\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )p({d_\\textrm{p}})} \\textrm{d}{d_\\textrm{p}}}}{{\\int {{S_\\textrm{p}}({{t_{\\max }},\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )p({d_\\textrm{p}})} \\textrm{d}{d_\\textrm{p}}}}$$\n\nFinally, substituting Eq. (15) into Eq. (21) yields\n\n$$R{S_{\\textrm{LII}}}(t )= \\frac{{\\int {\\frac{{d_\\textrm{p}^3(t )p({d_\\textrm{p}})\\textrm{d}{d_\\textrm{p}}}}{{\\textrm{exp} [{hc/{\\lambda_{\\textrm{mea}}}{k_\\textrm{B}}T({t,\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )} ]- 1}}} }}{{\\int {\\frac{{d_\\textrm{p}^3({{t_{\\max }}} )p({d_\\textrm{p}})\\textrm{d}{d_\\textrm{p}}}}{{\\textrm{exp} [{hc/{\\lambda_{\\textrm{mea}}}{k_\\textrm{B}}T({{t_{\\max }},\\textrm{ }{\\alpha_{\\textrm{T, f}}}} )} ]- 1}}} }}$$\n\nIt can be seen from Eq. (22) that the inversion of αT, f and PPSD does not require the prior information of most full LII model parameters, especially aggregate structure, aggregate size distribution, and TAC, which greatly reduces the uncertainty from the model parameters.\n\n## 3. Inversion process\n\nIn the present study, we consider simultaneous determination of PPSD parameters and fractal-dependent TAC, i.e., variables x = [dp, g, σd, g, αT, f], from the relative intensity of TiRe-LII signal using a weighted least-squares approach, with an objective function\n\n$${f_{\\textrm{obj}}} = \\left\\|{\\frac{{{{\\textbf {b}}_{\\textrm{mea}}} - {{\\textbf {b}}_{\\textrm{est}}}}}{{{{\\textbf {b}}_{\\textrm{mea}}}}}} \\right\\|_2^2$$\nwhere bmea and best are the measured and the estimated values of the measurement data, taken as the normalized TiRe-LII signal at multiple time points, i.e. b = [RSLII (t1), RSLII (t2), RSLII (t3), …]. In this study, the covariance matrix adaptive evolution strategy (CMA-ES) algorithm is used to minimize objective function value, with the details provided in Refs. [38,39].\n\nThe overall inverse method presented in this work is evaluated by simulating data instead of real measurements, using some target value of objective parameters xtar. The present work avoids inverse crime [33,34] (wherein identical forward and inverse models are used, resulting in a trivial procedure where the target parameters are returned exactly) in two ways.\n\nFirst, noise is added to the signals. Two different noise models were considered. The first model follows from our previous studies [39,40], and only considering a signal-independent Gaussian error :\n\n$${{\\textbf {b}}_{\\textrm{mea}}} = {{\\textbf {b}}_{\\textrm{tar}}}(1 + \\gamma ){{\\textbf {n}}^\\textrm{G}}$$\nwhere btar is the target signal vector; γ is the scale factor in Gaussian error; nG is the standard normal random vector for Gaussian error. The second noise model is the general noise model of Sipkens et al. , which considers the Poisson-Gaussian error in single-shot signals and the shot-to-shot error,\n$${{\\textbf {b}}_{\\textrm{mea}}} = {{\\textbf {b}}_{\\textrm{tar}}} + \\underbrace{{\\tau n{{\\textbf {b}}_{\\textrm{tar}}}}}_{{\\textrm{Shot - to - shot error}}} + \\underbrace{{{{[\\theta (1 + \\tau n){{\\textbf {b}}_{\\textrm{tar}}}]}^{1/2}} \\circ {{\\textbf {n}}^\\textrm{P}}}}_{{\\textrm{Poisson error}}} + \\underbrace{{\\gamma {{\\textbf {n}}^\\textrm{G}}}}_{{\\textrm{Gaussian error}}}$$\nwhere n is a standard normal random variable; τ, θ, and γ are the characteristic parameters of the general model, which are the scale factors in the shot-to-shot error, Poisson error and Gaussian error, respectively; nP and nG are respectively the standard normal random vector for Poisson error and Gaussian error.\n\nSecond, we employ a double-model approach (cf. Fig. 2), in which simulated data is generated using the full LII model, Eqs. (1) and (2), and then interpreted with simplified LII model of Section 2.3. Characteristics of the inverse procedure can be evaluated based on the degree to which it can return the target value, with appropriate consideration of uncertainties.",
null,
"Fig. 2. Flowchart of double-model inversion process\n\n## 4. Results and discussion\n\n#### 4.1 Laser fluence selection\n\nSince this study is based on a low fluence case where particle temperature and mass changes caused by thermal radiation, sublimation, oxidation, and thermionic are expected to be negligible, it is necessary to determine the appropriate laser fluence range. A simple method is provided in Ref. , in which the transition fluence (the point on the fluence curve where sublimation effects become significant) is given by\n\n$${F_{\\textrm{ref}}} = \\frac{{{\\lambda _{\\textrm{inc}}}{\\rho _\\textrm{s}}{c_\\textrm{s}}({{T_{\\textrm{ref}}} - {T_\\textrm{g}}} )}}{{6\\pi E(m )}}$$\nwhere Tref is the transition temperature, which depends on the sublimation model parameters; Tg = 300 K is the ambient gas temperature. This yields an estimated reference fluence of 0.126 J/cm2. Due to the more complex model, polydispersity, particle size variation, and Np effects considered in this work, we seek to validate this value and expand this discussion using simulated temperature traces.\n\nIn Fig. 3(a), as the laser fluence increases from 0.10 J/cm2 to 0.15 J/cm2, the peak portion of the primary particle temperature curve becomes more prominent, leading to higher peak temperatures and longer high-temperature duration, so in Fig. 3(b), the particle mass loss increases with the increase of laser fluence. When the laser fluence exceeds the 0.15 J/cm2, the diameter of the primary particles cannot be regarded as a constant because of the continuous mass loss. Figure 3 is obtained when Np = 1 and dp = 10 nm. For more Np and larger dp, the thermal shielding effect will be more significant and the specific surface area will be smaller, resulting in a higher peak temperature and a flatter cooling curve, and then more particle mass loss. Therefore, from the perspective of particle mass loss, a suitable fluence of laser should not exceed 0.15 J/cm2.",
null,
"Fig. 3. Effects of different laser fluences on temperature and diameter decay rate of primary particles when Np = 1 and dp = 10 nm\n\nOn the other hand, the simplified LII model only considers the energy change caused by laser absorption and heat conduction, so the laser fluence should be also selected according to the errors caused by the energy equation approximation. As shown in Fig. 4, when laser fluence exceeds 0.10 J/cm2, the ratio of the energy sum of laser absorption and heat conduction to the total energy is less than 90% at high temperature. In terms of the energy equation error in the simplified LII model, a suitable fluence of laser should be lower than 0.10 J/cm2. But lower laser energy density is not conducive to reducing the overall error, because lower laser energy density will make the signal-to-noise ratio of TiRe-LII signal worse . Therefore, a laser fluence of 0.10 J/cm2 is selected in the present study.",
null,
"Fig. 4. (a) when Np = 1 and dp = 10 nm and (b) when Np = 600 and dp = 150 nm, the effect of different laser fluence on the ratio of the energy sum of laser absorption and heat conduction to the total energy\n\n#### 4.2 Simultaneously inferring PPSD parameters and fractal-dependent TAC\n\nIn this study, the simultaneous inference of PPSD parameters and fractal-dependent TAC are performed in different cases. Table 1 summarizes the basic settings of these cases. To investigate the influence of the measurement wavelength number and measurement noise level on the retrieval precision, two different measurement wavelength schemes were used under 4 different measurement noise levels (8 test cases in total) to evaluate the capability of simultaneously inferring PPSD and fractal-dependent TAC from normalized TiRe-LII. Figure 5 shows a set of noisy LII signal synthesized in this study.",
null,
"Fig. 5. Noisy LII signals synthesized by (a) the general noise model and (b) Gaussian model",
null,
"Table 1. Basic settings of the test cases\n\nTable 2 shows the retrieval results of three objective parameters in all 8 test cases. For the 4 cases of the general noise model, the noisy signals used for one inversion are synthesized from an average of 100 shots, while for the 4 cases of the Gaussian noise model, the noisy signals used for one inversion are from a single shot. Given the stochastic nature of the noisy signal synthesis, 100 different sets of noisy signals are evaluated in each case. Each case is evaluated in the following aspects: (1) SR: The success rate of the all 100 independent inversions; (2) Avg: The average value of all successful inversions of one objective parameter; (3) Std: The standard deviation of all successful inversions of one objective parameter; (4) ɛrel: Relative error of Avg relative to the target value. Here, successful inversion means that the inversion process can eventually converge to a specific value.",
null,
"Table 2. Retrieval results of three objective parameters in 8 test cases\n\nRegarding relative error of retrieval results, whether for Gaussian noise or general noise the ɛrel of αT, f, dp, g, and σd, g inferred at low noise level do not exceed 5%. For the cases of Gaussian noise, it is found that the ɛrel of αT, f and σd, g inferred at high Gaussian noise level exceeds 10%, while the relative error of dp, g is thoroughly below 5%. For the cases of general noise, the ɛrel of all three objective parameters basically increase as noise level becomes stronger. When using noisy signals measured at two wavelengths, the ɛrel of all objective parameters do not exceed 5% except for the ɛrel of dp, g and σd, g at high general noise. When using noisy signals at three wavelengths, the ɛrel of all objective parameters do not exceed 5% except for the ɛrel of σd, g at high general noise. The ɛrel of αT, f is thoroughly below 5% in all the cases of the general noise. In addition, the success rate of 100 inversions drops significantly at high noise level, and as the wavelength number of noisy signals increases, the success rate of 100 inversions increases. Table 2 indicates that the simultaneous inference of αT, f, dp, g, and σd, g can be accurately achieved at a relatively low noise level, but when the noise reaches a certain level, the resulting αT, f, dp, g, and σd, g may deviate seriously from their target values.\n\nRegarding the standard deviation of retrieval results, the Std of inferred dp, g is close to its value magnitude, while for the inferred αT, f and σd, g, the Std is at least one order of magnitude smaller than its value. It indicates that the resulting dp, g of 100 evaluations are distributed in a wider range, i.e. the uncertainty of dp, g is greater than that of αT, f and σd, g. The magnitude of the uncertainties of dp, g and σd, g are consistent with the results of Bayesian analysis in Ref. . The uncertainty of the inversion results of all objective parameters increases as the noise becomes stronger. Therefore, in order to obtain more accurate inversion results, it is necessary to average the results over multiple independent inversions, especially for dp, g.\n\nAccording to our previous studies [39,40], the retrieval precision of objective parameters is typically improved when increasing the measurement wavelength number, since it brings more available information for inversion. In this study, for the cases under general noise, the retrieval results using three-wavelength noise signals are significantly better than those obtained from two-wavelength noise signals. It indicates that under general noise, increasing measurement wavelength number can effectively improve the inversion accuracy and reduce the uncertainty. But for all cases under Gaussian noise, the increase of measurement wavelength number has little effect on the relative error and standard deviation of three objective parameters.\n\nIn addition, it is not comprehensive to evaluate the inversion of the PPSD only from the retrieval precision of characteristic parameters dp, g and σd, g. For a more direct evaluation, Fig. 6 shows the PPSD profiles drawn from the target value of dp, g and σd, g together with PPSD profiles drawn from retrieval results of dp, g and σd, g in Table 2. It can be seen that the inferred PPSD is sensitive to the noise level. The greater the noise level, the wider the inferred PPSD profiles, and the farther the inferred PPSD profiles deviate from the target profile. For the PPSD profiles inferred under Gaussian noise in Fig. 6(a), there is only a slight difference between PPSD profiles inferred from two-wavelength (2λ) noisy signal and three-wavelength (3λ) noisy signal. However, for the PPSD profiles inferred under general noise in Fig. 6(b), the PPSD profiles inferred from three-wavelength (3λ) noise signals are obviously closer to target PPSD profiles than PPSD profiles inferred from two-wavelength (2λ) noise signals at high noise level. It is consistent with the trend of the relative error of dp, g and σd, g in Table 2, indicating that using noisy signals measured at more wavelengths can improve retrieval results, especially at high general noise level.",
null,
"Fig. 6. Primary particle size distribution profiles derived from retrieval results of (a) Gaussian noise and (b) general noise cases in Table 2 together with the target value\n\n#### 4.3 Log contour analysis of the objective function\n\nSolving inverse problem of inferring three objective parameters is to find the point with the lowest objective function value from the three-dimensional (three-variable) domains. Therefore, the involved inverse problem can be analyzed from the perspective of the log contours of the objective function. Since it is computation-consuming to analyze all log-contours of the objective function from the three-dimensional (three variables) search domain with sufficient resolution, only three typical ones are selected from a large number of log contours of the objective function for analysis. These three log contours of the objective function are obtained by respectively fixing three variables to their target values, such as, the log contours of the objective function on the αT, f-dp, g plane is obtained when σd, g is fixed at 1.2. Figure 7 shows the log contours of the objective function on (a) σd, g-dp, g plane, (b) αT, f-dp, g plane, and αT, f-σd, g plane. The objective functions used in Fig. 7(a), (b) and (c) are based on a set of the normalized LII noise signal that can accurately infer αT, f, dp, g, and σd, g.",
null,
"Fig. 7. Log contours of the objective function on (a) σd, g - dp, g plane, (b) αT, f - dp, g plane, and αT, f - σd, g plane\n\nConsidering the analysis in Ref. , the objective function topography of Fig. 7(a) reveal a robust estimate of σd, g and dp, g. According to the objective function topography of Fig. 7(c), the estimate of αT, f and σd, g is likely to be robust. In Fig. 7(b), there is no minimum point, but a minimum valley. The objective function topography of Fig. 7(b) is consistent with that in Ref. and , arising from the conduction-dominated temperature decay. Previous studies [13,19] concluded that it was impossible to infer αT and dp, g from conduction-dominated LII. But in this study, reasonable αT, f and dp, g can be inferred from the conduction-dominated LII. In order to further verify the possibility of inferring αT, f and dp, g from the LII data, Fig. 8 shows the logarithmic objective function of valley lines of Fig. 7 along the coordinate axes.",
null,
"Fig. 8. Logarithmic objective function of valley lines of Fig. 6 along the coordinate axes\n\nFigure 8(a) and Fig. 8(d) are respectively the valley line of Fig. 7(a) along the dp, g-axis and σd, g-axis. In Fig. 8(a) and Fig. 8(d), the bottom of the valley line is U-shaped, with steep sides, from which the lowest point can be easily distinguished. The lowest points of dp, g and σd, g are respectively at 20 nm and 1.2, which are consistent with their target values. Due to the large slopes on both sides of the lowest point, the inversion process can easily converge to the lowest point, which indicates an accurate estimate of dp, g and σd, g when αT, f, is perfectly known. Figure 8(b) and Fig. 8(e) are respectively the valley line of Fig. 7(b) along the dp, g-axis and αT, f-axis. Although the bottom of the valley line is extremely flat, the insets of Fig. 8(b) and (e) prove the existence of the lowest points of dp, g and αT, f, at about 16.8 nm and 0.22, respectively. Due to the extremely small slopes on both sides of the lowest point, the inversion process is difficult to converge to the lowest point and may require a large number of iterations, which indicates that it is difficult but theoretically feasible to estimate dp, g and αT, f when σd, g is perfectly known. Figure 8(c) and Fig. 8(f) are respectively the valley line of Fig. 7(c) along the σd, g-axis and αT, f-axis. In Fig. 8(c) and (f), the lowest points of σd, g and αT, f are respectively at 1.2 and 0.26, which are consistent with their target values. But in Fig. 8(f), the valley line has two U-shaped bottoms with steep sides. The one on the right is the second lowest point of αT, f, which is about 0.36. Given that, it can be expected to accurately estimate σd, g and αT, f when dp, g is completely known, but it may happen that the retrieval process is trapped in the second lowest point where αT, f is about 0.36.\n\nFigure 7 and Fig. 8 actually correspond to three relatively simple two-variable inversions. Table 3 shows the retrieval results of these three two-variable inversions using the same noisy signal as Fig. 7 and Fig. 8. Each inversion is repeated 20 times to calculate the average results and the standard deviation. The 20 inversions finally converged to the same result, so the standard deviation of all variables is 0. The average estimated value of all variables is consistent with the minimum value in Fig. 8. the minimum value of αT, f and dp, g can be obtained stably (SR = 100%) in the current log contour topography of objective function. Regarding the average iteration counter, inferring αT, f and dp, g takes almost twice as much time as other two two-variable inversions. It can be seen that inferring αT, f and dp, g is much more difficult. In addition, the estimate of αT, f and σd, g has a 70% probability of failure. According to the results, the failed inversions are all be trapped in the area where αT, f is about 0.36. All these results verify our analysis of Fig. 8.",
null,
"Table 3. Retrieval results of three two-variable inversions\n\n## 5. Conclusion\n\nThis proof-of-concept study numerically evaluates the feasibility of simultaneously inferring PPSD and fractal-dependent TAC from normalized TiRe-LII signals. All the numerical evaluations are performed in the low-fluence case where the overall impact of TAC and fractal-dependent shielding factor on the simplified LII model can be defined as the fractal-dependent TAC. The full LII model is employed to synthesize normalized TiRe-LII signals for numerical evaluations, while the simplified model is used for the inverse problem analysis, which avoids the inverse crime. Based on normalized TiRe-LII signals and fractal-dependent TAC, the simplified LII model is independent of prior knowledge of most full LII model parameters, including fractal structure, the polydispersity of aggregate size, and absorption function at the measurement wavelength, the apparent fraction volume and calibration parameters.\n\nThe possibility of inferring PPSD parameters (dp, g and σd, g) and fractal-dependent TAC (αT, f) is numerically evaluated in 8 different cases under Gaussian noise or general noise. Regarding the relative error of retrieval results, the inference of dp, g, σd, g, and αT, f is accurate at low noise level but significantly biased at high noise level. For Gaussian noise, when more measurement wavelengths are used, the retrieval results are only slightly improved. For general noise, when more measurement wavelengths are used, especially for high noise level, the retrieval results are significantly improved. Regarding the uncertainty of retrieval results, to obtain a reliable estimate of dp, g, it is necessary to average multiple independent estimates. Regarding the log contour analysis of the objective function, although the inversion process is expected to be difficult due to the flat bottom line, the unique solution existing on the valley line theoretically proves the feasibility of inferring dp, g and αT, f.\n\nIn summary, all numerical results reveal the potential capability of simultaneously inferring PPSD and fractal-dependent TAC from normalized TiRe-LII signals. In this proof-of-concept, the inversion method is evaluated by simulation data instead of real measurements. Considering the essential difference between the simulation data and real measurements, the feasibility and predictive power of the method needs to be validated in controlled experiments with real measurement data. Further research will be conducted to prove the feasibility of this method experimentally. Furthermore, considering the large uncertainty of the inversion results in the current study, a full Bayesian inference will be employed in our future work to obtain reliable uncertainty estimates.\n\n## Funding\n\nNational Natural Science Foundation of China (51976044); National Science and Technology Planning Project (2017-V-0016-0069); Foundation for Heilongjiang Touyan Innovation Team Program.\n\n## Acknowledgements\n\nThe authors would like to thank Dr. Timothy Sipkens, Prof. Steven Rogak, and Miss Yilin Zhao for their direct input, insightful discussions, and editorial work on this manuscript. This paper also supported by the China Scholarship Council.\n\n## Disclosures\n\nThe authors declare no conflicts of interest.\n\n1. H. A. Michelsen, C. Schulz, G. J. Smallwood, and S. Will, “Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications,” Prog. Energy Combust. Sci. 51, 2–48 (2015). [CrossRef]\n\n2. V. Ramanathan and G. Carmichael, “Global and regional climate changes due to black carbon,” Nat. Geosci. 1(4), 221–227 (2008). [CrossRef]\n\n3. H. A. Michelsen, “Probing soot formation, chemical and physical evolution, and oxidation: A review of in situ diagnostic techniques and needs,” Proc. Combust. Inst. 36(1), 717–735 (2017). [CrossRef]\n\n4. T. R. Meyer, B. R. Halls, N. Jiang, M. N. Slipchenko, S. Roy, and J. R. Gord, “High-speed, three-dimensional tomographic laser-induced incandescence imaging of soot volume fraction in turbulent flames,” Opt. Express 24(26), 29547–29555 (2016). [CrossRef]\n\n5. P. Roth and A. V. Filippov, “In situ ultrafine particle sizing by a combination of pulsed laser heatup and particle thermal emission,” J. Aerosol Sci. 27(1), 95–104 (1996). [CrossRef]\n\n6. A. V. Filippov, M. W. Markus, and P. Roth, “In-situ characterization of ultrafine particles by laser-induced incandescence: sizing and particle structure determination,” J. Aerosol Sci. 30(1), 71–87 (1999). [CrossRef]\n\n7. B. F. Kock, T. Eckhardt, and P. Roth, “In-cylinder sizing of diesel particles by time-resolved laser-induced incandescence (TR-LII),” Proc. Combust. Inst. 29(2), 2775–2782 (2002). [CrossRef]\n\n8. T. Lehre, H. Bockhorn, B. Jungfleisch, and R. Suntz, “Development of a measuring technique for simultaneous in situ detection of nanoscaled particle size distributions and gas temperatures,” Chemosphere 51(10), 1055–1061 (2003). [CrossRef]\n\n9. T. Lehre, B. Jungfleisch, R. Suntz, and H. Bockhorn, “Size distributions of nanoscaled particles and gas temperatures from time-resolved laser-induced-incandescence measurements,” Appl. Opt. 42(12), 2021–2030 (2003). [CrossRef]\n\n10. T. Lehre, R. Suntz, and H. Bockhorn, “Time-resolved two-color LII: size distributions of nano-particles from gas-to-particle synthesis,” Proc. Combust. Inst. 30(2), 2585–2593 (2005). [CrossRef]\n\n11. F. Liu, B. J. Stagg, D. R. Snelling, and G. J. Smallwood, “Effects of primary soot particle size distribution on the temperature of soot particles heated by a nanosecond pulsed laser in an atmospheric laminar diffusion flame,” Int. J. Heat Mass Transfer 49(3-4), 777–788 (2006). [CrossRef]\n\n12. S. Dankers and A. Leipertz, “Determination of primary particle size distributions from time-resolved laser-induced incandescence measurements,” Appl. Opt. 43(18), 3726–3731 (2004). [CrossRef]\n\n13. T. A. Sipkens, N. R. Singh, and K. J. Daun, “Time-resolved laser-induced incandescence characterization of metal nanoparticles,” Appl. Phys. B 123(1), 14 (2017). [CrossRef]\n\n14. H. A. Michelsen, “Derivation of a temperature-dependent accommodation coefficient for use in modeling laser-induced incandescence of soot,” Appl. Phys. B 94(1), 103–117 (2009). [CrossRef]\n\n15. K. J. Daun, “Thermal accommodation coefficients between polyatomic gas molecules and soot in laser-induced incandescence experiments,” Int. J. Heat Mass Transfer 52(21-22), 5081–5089 (2009). [CrossRef]\n\n16. K. Daun, F. Liu, and G. Smallwood, “Molecular dynamics simulations of translational thermal accommodation coefficients for time-resolved LII,” in Heat Transfer Summer Conference, 2008), 333–342.\n\n17. T. A. Sipkens and K. J. Daun, “Effect of Surface Interatomic Potential on Thermal Accommodation Coefficients Derived from Molecular Dynamics,” J. Phys. Chem. C 122(35), 20431–20443 (2018). [CrossRef]\n\n18. B. F. Kock, C. Kayan, J. Knipping, H. R. Orthner, and P. Roth, “Comparison of LII and TEM sizing during synthesis of iron particle chains,” Proc. Combust. Inst. 30(1), 1689–1697 (2005). [CrossRef]\n\n19. T. Sipkens, G. Joshi, K. J. Daun, and Y. Murakami, “Sizing of molybdenum nanoparticles using time-resolved laser-induced incandescence,” J. Heat Transfer 135, 549–557 (2013). [CrossRef]\n\n20. F. J. Bauer, K. J. Daun, F. J. T. Huber, and S. Will, “Can soot primary particle size distributions be determined using laser-induced incandescence?” Appl. Phys. B 125(6), 109 (2019). [CrossRef]\n\n21. J. P. Abrahamson, M. Singh, J. P. Mathews, and R. L. Vander Wal, “Pulsed laser annealing of carbon black,” Carbon 124, 380–390 (2017). [CrossRef]\n\n22. B. Apicella, A. Ciajolo, A. Tregrossi, J. Abrahamson, R. L. Vander Wal, and C. Russo, “HRTEM and EELS investigations of flame-formed soot nanostructure,” Fuel 225, 218–224 (2018). [CrossRef]\n\n23. B. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019). [CrossRef]\n\n24. R. L. Vander Wal and M. Y. Choi, “Pulsed laser heating of soot: morphological changes,” Carbon 37(2), 231–239 (1999). [CrossRef]\n\n25. R. L. Vander Wal and A. J. Tomasek, “Soot nanostructure: dependence upon synthesis conditions,” Combust. Flame 136(1-2), 129–140 (2004). [CrossRef]\n\n26. K. Yehliu, R. L. Vander Wal, and A. L. Boehman, “Development of an HRTEM image analysis method to quantify carbon nanostructure,” Combust. Flame 158(9), 1837–1851 (2011). [CrossRef]\n\n27. H. A. Michelsen, “Understanding and predicting the temporal response of laser-induced incandescence from carbonaceous particles,” J. Phys. Chem. C 118(15), 7012–7045 (2003). [CrossRef]\n\n28. C. F. Bohren and D. R. Huffman, Absorption and scattering of light by small particles (John Wiley & Sons, 2008).\n\n29. H. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007). [CrossRef]\n\n30. F. Liu, M. Yang, F. A. Hill, D. R. Snelling, and G. J. Smallwood, “Influence of polydisperse distributions of both primary particle and aggregate size on soot temperature in low-fluence LII,” Appl. Phys. B 83(3), 383–395 (2006). [CrossRef]\n\n31. C. M. Sorensen, “Light Scattering by Fractal Aggregates: A Review,” Aerosol Sci. Technol. 35(2), 648–687 (2001). [CrossRef]\n\n32. A. V. Filippov, M. Zurita, and D. E. Rosner, “Fractal-like Aggregates: Relation between Morphology and Physical Properties,” J. Colloid Interface Sci. 229(1), 261–273 (2000). [CrossRef]\n\n33. D. Colton and R. Kress, Inverse acoustic and electromagnetic scattering theory (Springer Nature, 2019), Vol. 93.\n\n34. J. Kaipio and E. Somersalo, “Statistical inverse problems: Discretization, model reduction and inverse crimes,” J. Comput. Appl. Math. 198(2), 493–504 (2007). [CrossRef]\n\n35. U. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020). [CrossRef]\n\n36. J. Olfert and S. Rogak, “Universal relations between soot effective density and primary particle size for common combustion sources,” Aerosol Sci. Technol. 53(5), 485–492 (2019). [CrossRef]\n\n37. P. Desgroux, X. Mercier, and K. A. Thomson, “Study of the formation of soot and its precursors in flames using optical diagnostics,” Proc. Combust. Inst. 34(1), 1713–1738 (2013). [CrossRef]\n\n38. J.-W. Shi, H. Qi, J.-Y. Zhang, Y.-T. Ren, L.-M. Ruan, and Y. Zhang, “Simultaneous measurement of flame temperature and species concentration distribution from nonlinear tomographic absorption spectroscopy,” J. Quant. Spectrosc. Radiat. Transfer 241, 106693 (2020). [CrossRef]\n\n39. J.-Y. Zhang, H. Qi, Y.-F. Wang, B.-H. Gao, and L.-M. Ruan, “Retrieval of fractal dimension and size distribution of non-compact soot aggregates from relative intensities of multi-wavelength angular-resolved light scattering,” Opt. Express 27(2), 1613 (2019). [CrossRef]\n\n40. J.-Y. Zhang, H. Qi, Y.-T. Ren, and L.-M. Ruan, “Simultaneous identification of optical constants and PSD of spherical particles by multi-wavelength scattering–transmittance measurement,” Opt. Commun. 413, 317–328 (2018). [CrossRef]\n\n41. T. A. Sipkens, P. J. Hadwin, S. J. Grauer, and K. J. Daun, “General error model for analysis of laser-induced incandescence signals,” Appl. Opt. 56(30), 8436–8445 (2017). [CrossRef]\n\n42. T. A. Sipkens and K. J. Daun, “Defining regimes and analytical expressions for fluence curves in pulsed laser heating of aerosolized nanoparticles,” Opt. Express 25(5), 5684–5696 (2017). [CrossRef]\n\n### References\n\n• View by:\n• |\n• |\n• |\n\n1. H. A. Michelsen, C. Schulz, G. J. Smallwood, and S. Will, “Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications,” Prog. Energy Combust. Sci. 51, 2–48 (2015).\n[Crossref]\n2. V. Ramanathan and G. Carmichael, “Global and regional climate changes due to black carbon,” Nat. Geosci. 1(4), 221–227 (2008).\n[Crossref]\n3. H. A. Michelsen, “Probing soot formation, chemical and physical evolution, and oxidation: A review of in situ diagnostic techniques and needs,” Proc. Combust. Inst. 36(1), 717–735 (2017).\n[Crossref]\n4. T. R. Meyer, B. R. Halls, N. Jiang, M. N. Slipchenko, S. Roy, and J. R. Gord, “High-speed, three-dimensional tomographic laser-induced incandescence imaging of soot volume fraction in turbulent flames,” Opt. Express 24(26), 29547–29555 (2016).\n[Crossref]\n5. P. Roth and A. V. Filippov, “In situ ultrafine particle sizing by a combination of pulsed laser heatup and particle thermal emission,” J. Aerosol Sci. 27(1), 95–104 (1996).\n[Crossref]\n6. A. V. Filippov, M. W. Markus, and P. Roth, “In-situ characterization of ultrafine particles by laser-induced incandescence: sizing and particle structure determination,” J. Aerosol Sci. 30(1), 71–87 (1999).\n[Crossref]\n7. B. F. Kock, T. Eckhardt, and P. Roth, “In-cylinder sizing of diesel particles by time-resolved laser-induced incandescence (TR-LII),” Proc. Combust. Inst. 29(2), 2775–2782 (2002).\n[Crossref]\n8. T. Lehre, H. Bockhorn, B. Jungfleisch, and R. Suntz, “Development of a measuring technique for simultaneous in situ detection of nanoscaled particle size distributions and gas temperatures,” Chemosphere 51(10), 1055–1061 (2003).\n[Crossref]\n9. T. Lehre, B. Jungfleisch, R. Suntz, and H. Bockhorn, “Size distributions of nanoscaled particles and gas temperatures from time-resolved laser-induced-incandescence measurements,” Appl. Opt. 42(12), 2021–2030 (2003).\n[Crossref]\n10. T. Lehre, R. Suntz, and H. Bockhorn, “Time-resolved two-color LII: size distributions of nano-particles from gas-to-particle synthesis,” Proc. Combust. Inst. 30(2), 2585–2593 (2005).\n[Crossref]\n11. F. Liu, B. J. Stagg, D. R. Snelling, and G. J. Smallwood, “Effects of primary soot particle size distribution on the temperature of soot particles heated by a nanosecond pulsed laser in an atmospheric laminar diffusion flame,” Int. J. Heat Mass Transfer 49(3-4), 777–788 (2006).\n[Crossref]\n12. S. Dankers and A. Leipertz, “Determination of primary particle size distributions from time-resolved laser-induced incandescence measurements,” Appl. Opt. 43(18), 3726–3731 (2004).\n[Crossref]\n13. T. A. Sipkens, N. R. Singh, and K. J. Daun, “Time-resolved laser-induced incandescence characterization of metal nanoparticles,” Appl. Phys. B 123(1), 14 (2017).\n[Crossref]\n14. H. A. Michelsen, “Derivation of a temperature-dependent accommodation coefficient for use in modeling laser-induced incandescence of soot,” Appl. Phys. B 94(1), 103–117 (2009).\n[Crossref]\n15. K. J. Daun, “Thermal accommodation coefficients between polyatomic gas molecules and soot in laser-induced incandescence experiments,” Int. J. Heat Mass Transfer 52(21-22), 5081–5089 (2009).\n[Crossref]\n16. K. Daun, F. Liu, and G. Smallwood, “Molecular dynamics simulations of translational thermal accommodation coefficients for time-resolved LII,” in Heat Transfer Summer Conference, 2008), 333–342.\n17. T. A. Sipkens and K. J. Daun, “Effect of Surface Interatomic Potential on Thermal Accommodation Coefficients Derived from Molecular Dynamics,” J. Phys. Chem. C 122(35), 20431–20443 (2018).\n[Crossref]\n18. B. F. Kock, C. Kayan, J. Knipping, H. R. Orthner, and P. Roth, “Comparison of LII and TEM sizing during synthesis of iron particle chains,” Proc. Combust. Inst. 30(1), 1689–1697 (2005).\n[Crossref]\n19. T. Sipkens, G. Joshi, K. J. Daun, and Y. Murakami, “Sizing of molybdenum nanoparticles using time-resolved laser-induced incandescence,” J. Heat Transfer 135, 549–557 (2013).\n[Crossref]\n20. F. J. Bauer, K. J. Daun, F. J. T. Huber, and S. Will, “Can soot primary particle size distributions be determined using laser-induced incandescence?” Appl. Phys. B 125(6), 109 (2019).\n[Crossref]\n21. J. P. Abrahamson, M. Singh, J. P. Mathews, and R. L. Vander Wal, “Pulsed laser annealing of carbon black,” Carbon 124, 380–390 (2017).\n[Crossref]\n22. B. Apicella, A. Ciajolo, A. Tregrossi, J. Abrahamson, R. L. Vander Wal, and C. Russo, “HRTEM and EELS investigations of flame-formed soot nanostructure,” Fuel 225, 218–224 (2018).\n[Crossref]\n23. B. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n24. R. L. Vander Wal and M. Y. Choi, “Pulsed laser heating of soot: morphological changes,” Carbon 37(2), 231–239 (1999).\n[Crossref]\n25. R. L. Vander Wal and A. J. Tomasek, “Soot nanostructure: dependence upon synthesis conditions,” Combust. Flame 136(1-2), 129–140 (2004).\n[Crossref]\n26. K. Yehliu, R. L. Vander Wal, and A. L. Boehman, “Development of an HRTEM image analysis method to quantify carbon nanostructure,” Combust. Flame 158(9), 1837–1851 (2011).\n[Crossref]\n27. H. A. Michelsen, “Understanding and predicting the temporal response of laser-induced incandescence from carbonaceous particles,” J. Phys. Chem. C 118(15), 7012–7045 (2003).\n[Crossref]\n28. C. F. Bohren and D. R. Huffman, Absorption and scattering of light by small particles (John Wiley & Sons, 2008).\n29. H. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n30. F. Liu, M. Yang, F. A. Hill, D. R. Snelling, and G. J. Smallwood, “Influence of polydisperse distributions of both primary particle and aggregate size on soot temperature in low-fluence LII,” Appl. Phys. B 83(3), 383–395 (2006).\n[Crossref]\n31. C. M. Sorensen, “Light Scattering by Fractal Aggregates: A Review,” Aerosol Sci. Technol. 35(2), 648–687 (2001).\n[Crossref]\n32. A. V. Filippov, M. Zurita, and D. E. Rosner, “Fractal-like Aggregates: Relation between Morphology and Physical Properties,” J. Colloid Interface Sci. 229(1), 261–273 (2000).\n[Crossref]\n33. D. Colton and R. Kress, Inverse acoustic and electromagnetic scattering theory (Springer Nature, 2019), Vol. 93.\n34. J. Kaipio and E. Somersalo, “Statistical inverse problems: Discretization, model reduction and inverse crimes,” J. Comput. Appl. Math. 198(2), 493–504 (2007).\n[Crossref]\n35. U. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n36. J. Olfert and S. Rogak, “Universal relations between soot effective density and primary particle size for common combustion sources,” Aerosol Sci. Technol. 53(5), 485–492 (2019).\n[Crossref]\n37. P. Desgroux, X. Mercier, and K. A. Thomson, “Study of the formation of soot and its precursors in flames using optical diagnostics,” Proc. Combust. Inst. 34(1), 1713–1738 (2013).\n[Crossref]\n38. J.-W. Shi, H. Qi, J.-Y. Zhang, Y.-T. Ren, L.-M. Ruan, and Y. Zhang, “Simultaneous measurement of flame temperature and species concentration distribution from nonlinear tomographic absorption spectroscopy,” J. Quant. Spectrosc. Radiat. Transfer 241, 106693 (2020).\n[Crossref]\n39. J.-Y. Zhang, H. Qi, Y.-F. Wang, B.-H. Gao, and L.-M. Ruan, “Retrieval of fractal dimension and size distribution of non-compact soot aggregates from relative intensities of multi-wavelength angular-resolved light scattering,” Opt. Express 27(2), 1613 (2019).\n[Crossref]\n40. J.-Y. Zhang, H. Qi, Y.-T. Ren, and L.-M. Ruan, “Simultaneous identification of optical constants and PSD of spherical particles by multi-wavelength scattering–transmittance measurement,” Opt. Commun. 413, 317–328 (2018).\n[Crossref]\n41. T. A. Sipkens, P. J. Hadwin, S. J. Grauer, and K. J. Daun, “General error model for analysis of laser-induced incandescence signals,” Appl. Opt. 56(30), 8436–8445 (2017).\n[Crossref]\n42. T. A. Sipkens and K. J. Daun, “Defining regimes and analytical expressions for fluence curves in pulsed laser heating of aerosolized nanoparticles,” Opt. Express 25(5), 5684–5696 (2017).\n[Crossref]\n\n#### 2020 (2)\n\nJ.-W. Shi, H. Qi, J.-Y. Zhang, Y.-T. Ren, L.-M. Ruan, and Y. Zhang, “Simultaneous measurement of flame temperature and species concentration distribution from nonlinear tomographic absorption spectroscopy,” J. Quant. Spectrosc. Radiat. Transfer 241, 106693 (2020).\n[Crossref]\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### 2019 (4)\n\nJ. Olfert and S. Rogak, “Universal relations between soot effective density and primary particle size for common combustion sources,” Aerosol Sci. Technol. 53(5), 485–492 (2019).\n[Crossref]\n\nF. J. Bauer, K. J. Daun, F. J. T. Huber, and S. Will, “Can soot primary particle size distributions be determined using laser-induced incandescence?” Appl. Phys. B 125(6), 109 (2019).\n[Crossref]\n\nB. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n\n#### 2018 (3)\n\nB. Apicella, A. Ciajolo, A. Tregrossi, J. Abrahamson, R. L. Vander Wal, and C. Russo, “HRTEM and EELS investigations of flame-formed soot nanostructure,” Fuel 225, 218–224 (2018).\n[Crossref]\n\nJ.-Y. Zhang, H. Qi, Y.-T. Ren, and L.-M. Ruan, “Simultaneous identification of optical constants and PSD of spherical particles by multi-wavelength scattering–transmittance measurement,” Opt. Commun. 413, 317–328 (2018).\n[Crossref]\n\nT. A. Sipkens and K. J. Daun, “Effect of Surface Interatomic Potential on Thermal Accommodation Coefficients Derived from Molecular Dynamics,” J. Phys. Chem. C 122(35), 20431–20443 (2018).\n[Crossref]\n\n#### 2017 (5)\n\nT. A. Sipkens, N. R. Singh, and K. J. Daun, “Time-resolved laser-induced incandescence characterization of metal nanoparticles,” Appl. Phys. B 123(1), 14 (2017).\n[Crossref]\n\nH. A. Michelsen, “Probing soot formation, chemical and physical evolution, and oxidation: A review of in situ diagnostic techniques and needs,” Proc. Combust. Inst. 36(1), 717–735 (2017).\n[Crossref]\n\nJ. P. Abrahamson, M. Singh, J. P. Mathews, and R. L. Vander Wal, “Pulsed laser annealing of carbon black,” Carbon 124, 380–390 (2017).\n[Crossref]\n\n#### 2015 (1)\n\nH. A. Michelsen, C. Schulz, G. J. Smallwood, and S. Will, “Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications,” Prog. Energy Combust. Sci. 51, 2–48 (2015).\n[Crossref]\n\n#### 2013 (2)\n\nT. Sipkens, G. Joshi, K. J. Daun, and Y. Murakami, “Sizing of molybdenum nanoparticles using time-resolved laser-induced incandescence,” J. Heat Transfer 135, 549–557 (2013).\n[Crossref]\n\nP. Desgroux, X. Mercier, and K. A. Thomson, “Study of the formation of soot and its precursors in flames using optical diagnostics,” Proc. Combust. Inst. 34(1), 1713–1738 (2013).\n[Crossref]\n\n#### 2011 (1)\n\nK. Yehliu, R. L. Vander Wal, and A. L. Boehman, “Development of an HRTEM image analysis method to quantify carbon nanostructure,” Combust. Flame 158(9), 1837–1851 (2011).\n[Crossref]\n\n#### 2009 (2)\n\nH. A. Michelsen, “Derivation of a temperature-dependent accommodation coefficient for use in modeling laser-induced incandescence of soot,” Appl. Phys. B 94(1), 103–117 (2009).\n[Crossref]\n\nK. J. Daun, “Thermal accommodation coefficients between polyatomic gas molecules and soot in laser-induced incandescence experiments,” Int. J. Heat Mass Transfer 52(21-22), 5081–5089 (2009).\n[Crossref]\n\n#### 2008 (1)\n\nV. Ramanathan and G. Carmichael, “Global and regional climate changes due to black carbon,” Nat. Geosci. 1(4), 221–227 (2008).\n[Crossref]\n\n#### 2007 (2)\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\nJ. Kaipio and E. Somersalo, “Statistical inverse problems: Discretization, model reduction and inverse crimes,” J. Comput. Appl. Math. 198(2), 493–504 (2007).\n[Crossref]\n\n#### 2006 (2)\n\nF. Liu, M. Yang, F. A. Hill, D. R. Snelling, and G. J. Smallwood, “Influence of polydisperse distributions of both primary particle and aggregate size on soot temperature in low-fluence LII,” Appl. Phys. B 83(3), 383–395 (2006).\n[Crossref]\n\nF. Liu, B. J. Stagg, D. R. Snelling, and G. J. Smallwood, “Effects of primary soot particle size distribution on the temperature of soot particles heated by a nanosecond pulsed laser in an atmospheric laminar diffusion flame,” Int. J. Heat Mass Transfer 49(3-4), 777–788 (2006).\n[Crossref]\n\n#### 2005 (2)\n\nT. Lehre, R. Suntz, and H. Bockhorn, “Time-resolved two-color LII: size distributions of nano-particles from gas-to-particle synthesis,” Proc. Combust. Inst. 30(2), 2585–2593 (2005).\n[Crossref]\n\nB. F. Kock, C. Kayan, J. Knipping, H. R. Orthner, and P. Roth, “Comparison of LII and TEM sizing during synthesis of iron particle chains,” Proc. Combust. Inst. 30(1), 1689–1697 (2005).\n[Crossref]\n\n#### 2004 (2)\n\nR. L. Vander Wal and A. J. Tomasek, “Soot nanostructure: dependence upon synthesis conditions,” Combust. Flame 136(1-2), 129–140 (2004).\n[Crossref]\n\n#### 2003 (3)\n\nH. A. Michelsen, “Understanding and predicting the temporal response of laser-induced incandescence from carbonaceous particles,” J. Phys. Chem. C 118(15), 7012–7045 (2003).\n[Crossref]\n\nT. Lehre, H. Bockhorn, B. Jungfleisch, and R. Suntz, “Development of a measuring technique for simultaneous in situ detection of nanoscaled particle size distributions and gas temperatures,” Chemosphere 51(10), 1055–1061 (2003).\n[Crossref]\n\n#### 2002 (1)\n\nB. F. Kock, T. Eckhardt, and P. Roth, “In-cylinder sizing of diesel particles by time-resolved laser-induced incandescence (TR-LII),” Proc. Combust. Inst. 29(2), 2775–2782 (2002).\n[Crossref]\n\n#### 2001 (1)\n\nC. M. Sorensen, “Light Scattering by Fractal Aggregates: A Review,” Aerosol Sci. Technol. 35(2), 648–687 (2001).\n[Crossref]\n\n#### 2000 (1)\n\nA. V. Filippov, M. Zurita, and D. E. Rosner, “Fractal-like Aggregates: Relation between Morphology and Physical Properties,” J. Colloid Interface Sci. 229(1), 261–273 (2000).\n[Crossref]\n\n#### 1999 (2)\n\nR. L. Vander Wal and M. Y. Choi, “Pulsed laser heating of soot: morphological changes,” Carbon 37(2), 231–239 (1999).\n[Crossref]\n\nA. V. Filippov, M. W. Markus, and P. Roth, “In-situ characterization of ultrafine particles by laser-induced incandescence: sizing and particle structure determination,” J. Aerosol Sci. 30(1), 71–87 (1999).\n[Crossref]\n\n#### 1996 (1)\n\nP. Roth and A. V. Filippov, “In situ ultrafine particle sizing by a combination of pulsed laser heatup and particle thermal emission,” J. Aerosol Sci. 27(1), 95–104 (1996).\n[Crossref]\n\n#### Abrahamson, J.\n\nB. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n\nB. Apicella, A. Ciajolo, A. Tregrossi, J. Abrahamson, R. L. Vander Wal, and C. Russo, “HRTEM and EELS investigations of flame-formed soot nanostructure,” Fuel 225, 218–224 (2018).\n[Crossref]\n\n#### Abrahamson, J. P.\n\nJ. P. Abrahamson, M. Singh, J. P. Mathews, and R. L. Vander Wal, “Pulsed laser annealing of carbon black,” Carbon 124, 380–390 (2017).\n[Crossref]\n\n#### Apicella, B.\n\nB. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n\nB. Apicella, A. Ciajolo, A. Tregrossi, J. Abrahamson, R. L. Vander Wal, and C. Russo, “HRTEM and EELS investigations of flame-formed soot nanostructure,” Fuel 225, 218–224 (2018).\n[Crossref]\n\n#### Baldelli, A.\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### Bauer, F. J.\n\nF. J. Bauer, K. J. Daun, F. J. T. Huber, and S. Will, “Can soot primary particle size distributions be determined using laser-induced incandescence?” Appl. Phys. B 125(6), 109 (2019).\n[Crossref]\n\n#### Bengtsson, P.-E.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Bockhorn, H.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\nT. Lehre, R. Suntz, and H. Bockhorn, “Time-resolved two-color LII: size distributions of nano-particles from gas-to-particle synthesis,” Proc. Combust. Inst. 30(2), 2585–2593 (2005).\n[Crossref]\n\nT. Lehre, H. Bockhorn, B. Jungfleisch, and R. Suntz, “Development of a measuring technique for simultaneous in situ detection of nanoscaled particle size distributions and gas temperatures,” Chemosphere 51(10), 1055–1061 (2003).\n[Crossref]\n\n#### Boehman, A. L.\n\nK. Yehliu, R. L. Vander Wal, and A. L. Boehman, “Development of an HRTEM image analysis method to quantify carbon nanostructure,” Combust. Flame 158(9), 1837–1851 (2011).\n[Crossref]\n\n#### Bohren, C. F.\n\nC. F. Bohren and D. R. Huffman, Absorption and scattering of light by small particles (John Wiley & Sons, 2008).\n\n#### Boïarciuc, A.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Carmichael, G.\n\nV. Ramanathan and G. Carmichael, “Global and regional climate changes due to black carbon,” Nat. Geosci. 1(4), 221–227 (2008).\n[Crossref]\n\n#### Charwath, M.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Choi, M. Y.\n\nR. L. Vander Wal and M. Y. Choi, “Pulsed laser heating of soot: morphological changes,” Carbon 37(2), 231–239 (1999).\n[Crossref]\n\n#### Ciajolo, A.\n\nB. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n\nB. Apicella, A. Ciajolo, A. Tregrossi, J. Abrahamson, R. L. Vander Wal, and C. Russo, “HRTEM and EELS investigations of flame-formed soot nanostructure,” Fuel 225, 218–224 (2018).\n[Crossref]\n\n#### Colton, D.\n\nD. Colton and R. Kress, Inverse acoustic and electromagnetic scattering theory (Springer Nature, 2019), Vol. 93.\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### Corbin, J. C.\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### Daun, K.\n\nK. Daun, F. Liu, and G. Smallwood, “Molecular dynamics simulations of translational thermal accommodation coefficients for time-resolved LII,” in Heat Transfer Summer Conference, 2008), 333–342.\n\n#### Daun, K. J.\n\nF. J. Bauer, K. J. Daun, F. J. T. Huber, and S. Will, “Can soot primary particle size distributions be determined using laser-induced incandescence?” Appl. Phys. B 125(6), 109 (2019).\n[Crossref]\n\nT. A. Sipkens and K. J. Daun, “Effect of Surface Interatomic Potential on Thermal Accommodation Coefficients Derived from Molecular Dynamics,” J. Phys. Chem. C 122(35), 20431–20443 (2018).\n[Crossref]\n\nT. A. Sipkens, N. R. Singh, and K. J. Daun, “Time-resolved laser-induced incandescence characterization of metal nanoparticles,” Appl. Phys. B 123(1), 14 (2017).\n[Crossref]\n\nT. Sipkens, G. Joshi, K. J. Daun, and Y. Murakami, “Sizing of molybdenum nanoparticles using time-resolved laser-induced incandescence,” J. Heat Transfer 135, 549–557 (2013).\n[Crossref]\n\nK. J. Daun, “Thermal accommodation coefficients between polyatomic gas molecules and soot in laser-induced incandescence experiments,” Int. J. Heat Mass Transfer 52(21-22), 5081–5089 (2009).\n[Crossref]\n\n#### Desgroux, P.\n\nP. Desgroux, X. Mercier, and K. A. Thomson, “Study of the formation of soot and its precursors in flames using optical diagnostics,” Proc. Combust. Inst. 34(1), 1713–1738 (2013).\n[Crossref]\n\n#### Dreier, T.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Eckhardt, T.\n\nB. F. Kock, T. Eckhardt, and P. Roth, “In-cylinder sizing of diesel particles by time-resolved laser-induced incandescence (TR-LII),” Proc. Combust. Inst. 29(2), 2775–2782 (2002).\n[Crossref]\n\n#### Filippov, A. V.\n\nA. V. Filippov, M. Zurita, and D. E. Rosner, “Fractal-like Aggregates: Relation between Morphology and Physical Properties,” J. Colloid Interface Sci. 229(1), 261–273 (2000).\n[Crossref]\n\nA. V. Filippov, M. W. Markus, and P. Roth, “In-situ characterization of ultrafine particles by laser-induced incandescence: sizing and particle structure determination,” J. Aerosol Sci. 30(1), 71–87 (1999).\n[Crossref]\n\nP. Roth and A. V. Filippov, “In situ ultrafine particle sizing by a combination of pulsed laser heatup and particle thermal emission,” J. Aerosol Sci. 27(1), 95–104 (1996).\n[Crossref]\n\n#### Foucher, F.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Geigle, K.-P.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Grauer, S. J.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Hill, F. A.\n\nF. Liu, M. Yang, F. A. Hill, D. R. Snelling, and G. J. Smallwood, “Influence of polydisperse distributions of both primary particle and aggregate size on soot temperature in low-fluence LII,” Appl. Phys. B 83(3), 383–395 (2006).\n[Crossref]\n\n#### Hofmann, M.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Huber, F. J. T.\n\nF. J. Bauer, K. J. Daun, F. J. T. Huber, and S. Will, “Can soot primary particle size distributions be determined using laser-induced incandescence?” Appl. Phys. B 125(6), 109 (2019).\n[Crossref]\n\n#### Huffman, D. R.\n\nC. F. Bohren and D. R. Huffman, Absorption and scattering of light by small particles (John Wiley & Sons, 2008).\n\n#### Jefferson, A. M.\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### Johnson, M. R.\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### Joshi, G.\n\nT. Sipkens, G. Joshi, K. J. Daun, and Y. Murakami, “Sizing of molybdenum nanoparticles using time-resolved laser-induced incandescence,” J. Heat Transfer 135, 549–557 (2013).\n[Crossref]\n\n#### Jungfleisch, B.\n\nT. Lehre, H. Bockhorn, B. Jungfleisch, and R. Suntz, “Development of a measuring technique for simultaneous in situ detection of nanoscaled particle size distributions and gas temperatures,” Chemosphere 51(10), 1055–1061 (2003).\n[Crossref]\n\n#### Kaipio, J.\n\nJ. Kaipio and E. Somersalo, “Statistical inverse problems: Discretization, model reduction and inverse crimes,” J. Comput. Appl. Math. 198(2), 493–504 (2007).\n[Crossref]\n\n#### Kayan, C.\n\nB. F. Kock, C. Kayan, J. Knipping, H. R. Orthner, and P. Roth, “Comparison of LII and TEM sizing during synthesis of iron particle chains,” Proc. Combust. Inst. 30(1), 1689–1697 (2005).\n[Crossref]\n\n#### Kazemimanesh, M.\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### Knipping, J.\n\nB. F. Kock, C. Kayan, J. Knipping, H. R. Orthner, and P. Roth, “Comparison of LII and TEM sizing during synthesis of iron particle chains,” Proc. Combust. Inst. 30(1), 1689–1697 (2005).\n[Crossref]\n\n#### Kock, B. F.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\nB. F. Kock, C. Kayan, J. Knipping, H. R. Orthner, and P. Roth, “Comparison of LII and TEM sizing during synthesis of iron particle chains,” Proc. Combust. Inst. 30(1), 1689–1697 (2005).\n[Crossref]\n\nB. F. Kock, T. Eckhardt, and P. Roth, “In-cylinder sizing of diesel particles by time-resolved laser-induced incandescence (TR-LII),” Proc. Combust. Inst. 29(2), 2775–2782 (2002).\n[Crossref]\n\n#### Kress, R.\n\nD. Colton and R. Kress, Inverse acoustic and electromagnetic scattering theory (Springer Nature, 2019), Vol. 93.\n\n#### Lehre, T.\n\nT. Lehre, R. Suntz, and H. Bockhorn, “Time-resolved two-color LII: size distributions of nano-particles from gas-to-particle synthesis,” Proc. Combust. Inst. 30(2), 2585–2593 (2005).\n[Crossref]\n\nT. Lehre, H. Bockhorn, B. Jungfleisch, and R. Suntz, “Development of a measuring technique for simultaneous in situ detection of nanoscaled particle size distributions and gas temperatures,” Chemosphere 51(10), 1055–1061 (2003).\n[Crossref]\n\n#### Liu, F.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\nF. Liu, M. Yang, F. A. Hill, D. R. Snelling, and G. J. Smallwood, “Influence of polydisperse distributions of both primary particle and aggregate size on soot temperature in low-fluence LII,” Appl. Phys. B 83(3), 383–395 (2006).\n[Crossref]\n\nF. Liu, B. J. Stagg, D. R. Snelling, and G. J. Smallwood, “Effects of primary soot particle size distribution on the temperature of soot particles heated by a nanosecond pulsed laser in an atmospheric laminar diffusion flame,” Int. J. Heat Mass Transfer 49(3-4), 777–788 (2006).\n[Crossref]\n\nK. Daun, F. Liu, and G. Smallwood, “Molecular dynamics simulations of translational thermal accommodation coefficients for time-resolved LII,” in Heat Transfer Summer Conference, 2008), 333–342.\n\n#### Markus, M. W.\n\nA. V. Filippov, M. W. Markus, and P. Roth, “In-situ characterization of ultrafine particles by laser-induced incandescence: sizing and particle structure determination,” J. Aerosol Sci. 30(1), 71–87 (1999).\n[Crossref]\n\n#### Mathews, J. P.\n\nJ. P. Abrahamson, M. Singh, J. P. Mathews, and R. L. Vander Wal, “Pulsed laser annealing of carbon black,” Carbon 124, 380–390 (2017).\n[Crossref]\n\n#### Mercier, X.\n\nP. Desgroux, X. Mercier, and K. A. Thomson, “Study of the formation of soot and its precursors in flames using optical diagnostics,” Proc. Combust. Inst. 34(1), 1713–1738 (2013).\n[Crossref]\n\n#### Michelsen, H. A.\n\nH. A. Michelsen, “Probing soot formation, chemical and physical evolution, and oxidation: A review of in situ diagnostic techniques and needs,” Proc. Combust. Inst. 36(1), 717–735 (2017).\n[Crossref]\n\nH. A. Michelsen, C. Schulz, G. J. Smallwood, and S. Will, “Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications,” Prog. Energy Combust. Sci. 51, 2–48 (2015).\n[Crossref]\n\nH. A. Michelsen, “Derivation of a temperature-dependent accommodation coefficient for use in modeling laser-induced incandescence of soot,” Appl. Phys. B 94(1), 103–117 (2009).\n[Crossref]\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\nH. A. Michelsen, “Understanding and predicting the temporal response of laser-induced incandescence from carbonaceous particles,” J. Phys. Chem. C 118(15), 7012–7045 (2003).\n[Crossref]\n\n#### Mounaïm-Rousselle, C.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Murakami, Y.\n\nT. Sipkens, G. Joshi, K. J. Daun, and Y. Murakami, “Sizing of molybdenum nanoparticles using time-resolved laser-induced incandescence,” J. Heat Transfer 135, 549–557 (2013).\n[Crossref]\n\n#### Olfert, J.\n\nJ. Olfert and S. Rogak, “Universal relations between soot effective density and primary particle size for common combustion sources,” Aerosol Sci. Technol. 53(5), 485–492 (2019).\n[Crossref]\n\n#### Olfert, J. S.\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### Orthner, H. R.\n\nB. F. Kock, C. Kayan, J. Knipping, H. R. Orthner, and P. Roth, “Comparison of LII and TEM sizing during synthesis of iron particle chains,” Proc. Combust. Inst. 30(1), 1689–1697 (2005).\n[Crossref]\n\n#### Pré, P.\n\nB. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n\n#### Qi, H.\n\nJ.-W. Shi, H. Qi, J.-Y. Zhang, Y.-T. Ren, L.-M. Ruan, and Y. Zhang, “Simultaneous measurement of flame temperature and species concentration distribution from nonlinear tomographic absorption spectroscopy,” J. Quant. Spectrosc. Radiat. Transfer 241, 106693 (2020).\n[Crossref]\n\nJ.-Y. Zhang, H. Qi, Y.-T. Ren, and L.-M. Ruan, “Simultaneous identification of optical constants and PSD of spherical particles by multi-wavelength scattering–transmittance measurement,” Opt. Commun. 413, 317–328 (2018).\n[Crossref]\n\n#### Ramanathan, V.\n\nV. Ramanathan and G. Carmichael, “Global and regional climate changes due to black carbon,” Nat. Geosci. 1(4), 221–227 (2008).\n[Crossref]\n\n#### Reimann, J.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Ren, Y.-T.\n\nJ.-W. Shi, H. Qi, J.-Y. Zhang, Y.-T. Ren, L.-M. Ruan, and Y. Zhang, “Simultaneous measurement of flame temperature and species concentration distribution from nonlinear tomographic absorption spectroscopy,” J. Quant. Spectrosc. Radiat. Transfer 241, 106693 (2020).\n[Crossref]\n\nJ.-Y. Zhang, H. Qi, Y.-T. Ren, and L.-M. Ruan, “Simultaneous identification of optical constants and PSD of spherical particles by multi-wavelength scattering–transmittance measurement,” Opt. Commun. 413, 317–328 (2018).\n[Crossref]\n\n#### Rogak, S.\n\nJ. Olfert and S. Rogak, “Universal relations between soot effective density and primary particle size for common combustion sources,” Aerosol Sci. Technol. 53(5), 485–492 (2019).\n[Crossref]\n\n#### Rogak, S. N.\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### Rosner, D. E.\n\nA. V. Filippov, M. Zurita, and D. E. Rosner, “Fractal-like Aggregates: Relation between Morphology and Physical Properties,” J. Colloid Interface Sci. 229(1), 261–273 (2000).\n[Crossref]\n\n#### Roth, P.\n\nB. F. Kock, C. Kayan, J. Knipping, H. R. Orthner, and P. Roth, “Comparison of LII and TEM sizing during synthesis of iron particle chains,” Proc. Combust. Inst. 30(1), 1689–1697 (2005).\n[Crossref]\n\nB. F. Kock, T. Eckhardt, and P. Roth, “In-cylinder sizing of diesel particles by time-resolved laser-induced incandescence (TR-LII),” Proc. Combust. Inst. 29(2), 2775–2782 (2002).\n[Crossref]\n\nA. V. Filippov, M. W. Markus, and P. Roth, “In-situ characterization of ultrafine particles by laser-induced incandescence: sizing and particle structure determination,” J. Aerosol Sci. 30(1), 71–87 (1999).\n[Crossref]\n\nP. Roth and A. V. Filippov, “In situ ultrafine particle sizing by a combination of pulsed laser heatup and particle thermal emission,” J. Aerosol Sci. 27(1), 95–104 (1996).\n[Crossref]\n\n#### Rouzaud, J. N.\n\nB. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n\n#### Ruan, L.-M.\n\nJ.-W. Shi, H. Qi, J.-Y. Zhang, Y.-T. Ren, L.-M. Ruan, and Y. Zhang, “Simultaneous measurement of flame temperature and species concentration distribution from nonlinear tomographic absorption spectroscopy,” J. Quant. Spectrosc. Radiat. Transfer 241, 106693 (2020).\n[Crossref]\n\nJ.-Y. Zhang, H. Qi, Y.-T. Ren, and L.-M. Ruan, “Simultaneous identification of optical constants and PSD of spherical particles by multi-wavelength scattering–transmittance measurement,” Opt. Commun. 413, 317–328 (2018).\n[Crossref]\n\n#### Russo, C.\n\nB. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n\nB. Apicella, A. Ciajolo, A. Tregrossi, J. Abrahamson, R. L. Vander Wal, and C. Russo, “HRTEM and EELS investigations of flame-formed soot nanostructure,” Fuel 225, 218–224 (2018).\n[Crossref]\n\n#### Schulz, C.\n\nH. A. Michelsen, C. Schulz, G. J. Smallwood, and S. Will, “Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications,” Prog. Energy Combust. Sci. 51, 2–48 (2015).\n[Crossref]\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Shi, J.-W.\n\nJ.-W. Shi, H. Qi, J.-Y. Zhang, Y.-T. Ren, L.-M. Ruan, and Y. Zhang, “Simultaneous measurement of flame temperature and species concentration distribution from nonlinear tomographic absorption spectroscopy,” J. Quant. Spectrosc. Radiat. Transfer 241, 106693 (2020).\n[Crossref]\n\n#### Singh, M.\n\nJ. P. Abrahamson, M. Singh, J. P. Mathews, and R. L. Vander Wal, “Pulsed laser annealing of carbon black,” Carbon 124, 380–390 (2017).\n[Crossref]\n\n#### Singh, N. R.\n\nT. A. Sipkens, N. R. Singh, and K. J. Daun, “Time-resolved laser-induced incandescence characterization of metal nanoparticles,” Appl. Phys. B 123(1), 14 (2017).\n[Crossref]\n\n#### Sipkens, T.\n\nT. Sipkens, G. Joshi, K. J. Daun, and Y. Murakami, “Sizing of molybdenum nanoparticles using time-resolved laser-induced incandescence,” J. Heat Transfer 135, 549–557 (2013).\n[Crossref]\n\n#### Sipkens, T. A.\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\nT. A. Sipkens and K. J. Daun, “Effect of Surface Interatomic Potential on Thermal Accommodation Coefficients Derived from Molecular Dynamics,” J. Phys. Chem. C 122(35), 20431–20443 (2018).\n[Crossref]\n\nT. A. Sipkens, N. R. Singh, and K. J. Daun, “Time-resolved laser-induced incandescence characterization of metal nanoparticles,” Appl. Phys. B 123(1), 14 (2017).\n[Crossref]\n\n#### Smallwood, G.\n\nK. Daun, F. Liu, and G. Smallwood, “Molecular dynamics simulations of translational thermal accommodation coefficients for time-resolved LII,” in Heat Transfer Summer Conference, 2008), 333–342.\n\n#### Smallwood, G. J.\n\nH. A. Michelsen, C. Schulz, G. J. Smallwood, and S. Will, “Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications,” Prog. Energy Combust. Sci. 51, 2–48 (2015).\n[Crossref]\n\nF. Liu, B. J. Stagg, D. R. Snelling, and G. J. Smallwood, “Effects of primary soot particle size distribution on the temperature of soot particles heated by a nanosecond pulsed laser in an atmospheric laminar diffusion flame,” Int. J. Heat Mass Transfer 49(3-4), 777–788 (2006).\n[Crossref]\n\nF. Liu, M. Yang, F. A. Hill, D. R. Snelling, and G. J. Smallwood, “Influence of polydisperse distributions of both primary particle and aggregate size on soot temperature in low-fluence LII,” Appl. Phys. B 83(3), 383–395 (2006).\n[Crossref]\n\n#### Snelling, D. R.\n\nF. Liu, M. Yang, F. A. Hill, D. R. Snelling, and G. J. Smallwood, “Influence of polydisperse distributions of both primary particle and aggregate size on soot temperature in low-fluence LII,” Appl. Phys. B 83(3), 383–395 (2006).\n[Crossref]\n\nF. Liu, B. J. Stagg, D. R. Snelling, and G. J. Smallwood, “Effects of primary soot particle size distribution on the temperature of soot particles heated by a nanosecond pulsed laser in an atmospheric laminar diffusion flame,” Int. J. Heat Mass Transfer 49(3-4), 777–788 (2006).\n[Crossref]\n\n#### Somersalo, E.\n\nJ. Kaipio and E. Somersalo, “Statistical inverse problems: Discretization, model reduction and inverse crimes,” J. Comput. Appl. Math. 198(2), 493–504 (2007).\n[Crossref]\n\n#### Sorensen, C. M.\n\nC. M. Sorensen, “Light Scattering by Fractal Aggregates: A Review,” Aerosol Sci. Technol. 35(2), 648–687 (2001).\n[Crossref]\n\n#### Stagg, B. J.\n\nF. Liu, B. J. Stagg, D. R. Snelling, and G. J. Smallwood, “Effects of primary soot particle size distribution on the temperature of soot particles heated by a nanosecond pulsed laser in an atmospheric laminar diffusion flame,” Int. J. Heat Mass Transfer 49(3-4), 777–788 (2006).\n[Crossref]\n\n#### Stirn, R.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Suntz, R.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\nT. Lehre, R. Suntz, and H. Bockhorn, “Time-resolved two-color LII: size distributions of nano-particles from gas-to-particle synthesis,” Proc. Combust. Inst. 30(2), 2585–2593 (2005).\n[Crossref]\n\nT. Lehre, H. Bockhorn, B. Jungfleisch, and R. Suntz, “Development of a measuring technique for simultaneous in situ detection of nanoscaled particle size distributions and gas temperatures,” Chemosphere 51(10), 1055–1061 (2003).\n[Crossref]\n\n#### Thomson, K. A.\n\nP. Desgroux, X. Mercier, and K. A. Thomson, “Study of the formation of soot and its precursors in flames using optical diagnostics,” Proc. Combust. Inst. 34(1), 1713–1738 (2013).\n[Crossref]\n\n#### Tomasek, A. J.\n\nR. L. Vander Wal and A. J. Tomasek, “Soot nanostructure: dependence upon synthesis conditions,” Combust. Flame 136(1-2), 129–140 (2004).\n[Crossref]\n\n#### Tregrossi, A.\n\nB. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n\nB. Apicella, A. Ciajolo, A. Tregrossi, J. Abrahamson, R. L. Vander Wal, and C. Russo, “HRTEM and EELS investigations of flame-formed soot nanostructure,” Fuel 225, 218–224 (2018).\n[Crossref]\n\n#### Tribalet, B.\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Trivanovic, U.\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### Vander Wal, R. L.\n\nB. Apicella, A. Ciajolo, A. Tregrossi, J. Abrahamson, R. L. Vander Wal, and C. Russo, “HRTEM and EELS investigations of flame-formed soot nanostructure,” Fuel 225, 218–224 (2018).\n[Crossref]\n\nJ. P. Abrahamson, M. Singh, J. P. Mathews, and R. L. Vander Wal, “Pulsed laser annealing of carbon black,” Carbon 124, 380–390 (2017).\n[Crossref]\n\nK. Yehliu, R. L. Vander Wal, and A. L. Boehman, “Development of an HRTEM image analysis method to quantify carbon nanostructure,” Combust. Flame 158(9), 1837–1851 (2011).\n[Crossref]\n\nR. L. Vander Wal and A. J. Tomasek, “Soot nanostructure: dependence upon synthesis conditions,” Combust. Flame 136(1-2), 129–140 (2004).\n[Crossref]\n\nR. L. Vander Wal and M. Y. Choi, “Pulsed laser heating of soot: morphological changes,” Carbon 37(2), 231–239 (1999).\n[Crossref]\n\n#### Wal, R. L. V.\n\nB. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n\n#### Will, S.\n\nF. J. Bauer, K. J. Daun, F. J. T. Huber, and S. Will, “Can soot primary particle size distributions be determined using laser-induced incandescence?” Appl. Phys. B 125(6), 109 (2019).\n[Crossref]\n\nH. A. Michelsen, C. Schulz, G. J. Smallwood, and S. Will, “Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications,” Prog. Energy Combust. Sci. 51, 2–48 (2015).\n[Crossref]\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\n#### Yang, M.\n\nF. Liu, M. Yang, F. A. Hill, D. R. Snelling, and G. J. Smallwood, “Influence of polydisperse distributions of both primary particle and aggregate size on soot temperature in low-fluence LII,” Appl. Phys. B 83(3), 383–395 (2006).\n[Crossref]\n\n#### Yehliu, K.\n\nK. Yehliu, R. L. Vander Wal, and A. L. Boehman, “Development of an HRTEM image analysis method to quantify carbon nanostructure,” Combust. Flame 158(9), 1837–1851 (2011).\n[Crossref]\n\n#### Zhang, J.-Y.\n\nJ.-W. Shi, H. Qi, J.-Y. Zhang, Y.-T. Ren, L.-M. Ruan, and Y. Zhang, “Simultaneous measurement of flame temperature and species concentration distribution from nonlinear tomographic absorption spectroscopy,” J. Quant. Spectrosc. Radiat. Transfer 241, 106693 (2020).\n[Crossref]\n\nJ.-Y. Zhang, H. Qi, Y.-T. Ren, and L.-M. Ruan, “Simultaneous identification of optical constants and PSD of spherical particles by multi-wavelength scattering–transmittance measurement,” Opt. Commun. 413, 317–328 (2018).\n[Crossref]\n\n#### Zhang, Y.\n\nJ.-W. Shi, H. Qi, J.-Y. Zhang, Y.-T. Ren, L.-M. Ruan, and Y. Zhang, “Simultaneous measurement of flame temperature and species concentration distribution from nonlinear tomographic absorption spectroscopy,” J. Quant. Spectrosc. Radiat. Transfer 241, 106693 (2020).\n[Crossref]\n\n#### Zurita, M.\n\nA. V. Filippov, M. Zurita, and D. E. Rosner, “Fractal-like Aggregates: Relation between Morphology and Physical Properties,” J. Colloid Interface Sci. 229(1), 261–273 (2000).\n[Crossref]\n\n#### Aerosol Sci. Technol. (2)\n\nC. M. Sorensen, “Light Scattering by Fractal Aggregates: A Review,” Aerosol Sci. Technol. 35(2), 648–687 (2001).\n[Crossref]\n\nJ. Olfert and S. Rogak, “Universal relations between soot effective density and primary particle size for common combustion sources,” Aerosol Sci. Technol. 53(5), 485–492 (2019).\n[Crossref]\n\n#### Appl. Phys. B (5)\n\nT. A. Sipkens, N. R. Singh, and K. J. Daun, “Time-resolved laser-induced incandescence characterization of metal nanoparticles,” Appl. Phys. B 123(1), 14 (2017).\n[Crossref]\n\nH. A. Michelsen, “Derivation of a temperature-dependent accommodation coefficient for use in modeling laser-induced incandescence of soot,” Appl. Phys. B 94(1), 103–117 (2009).\n[Crossref]\n\nH. A. Michelsen, F. Liu, B. F. Kock, H. Bladh, A. Boïarciuc, M. Charwath, T. Dreier, R. Hadef, M. Hofmann, J. Reimann, S. Will, P.-E. Bengtsson, H. Bockhorn, F. Foucher, K.-P. Geigle, C. Mounaïm-Rousselle, C. Schulz, R. Stirn, B. Tribalet, and R. Suntz, “Modeling laser-induced incandescence of soot: a summary and comparison of LII models,” Appl. Phys. B 87(3), 503–521 (2007).\n[Crossref]\n\nF. Liu, M. Yang, F. A. Hill, D. R. Snelling, and G. J. Smallwood, “Influence of polydisperse distributions of both primary particle and aggregate size on soot temperature in low-fluence LII,” Appl. Phys. B 83(3), 383–395 (2006).\n[Crossref]\n\nF. J. Bauer, K. J. Daun, F. J. T. Huber, and S. Will, “Can soot primary particle size distributions be determined using laser-induced incandescence?” Appl. Phys. B 125(6), 109 (2019).\n[Crossref]\n\n#### Carbon (2)\n\nJ. P. Abrahamson, M. Singh, J. P. Mathews, and R. L. Vander Wal, “Pulsed laser annealing of carbon black,” Carbon 124, 380–390 (2017).\n[Crossref]\n\nR. L. Vander Wal and M. Y. Choi, “Pulsed laser heating of soot: morphological changes,” Carbon 37(2), 231–239 (1999).\n[Crossref]\n\n#### Chemosphere (1)\n\nT. Lehre, H. Bockhorn, B. Jungfleisch, and R. Suntz, “Development of a measuring technique for simultaneous in situ detection of nanoscaled particle size distributions and gas temperatures,” Chemosphere 51(10), 1055–1061 (2003).\n[Crossref]\n\n#### Combust. Flame (3)\n\nR. L. Vander Wal and A. J. Tomasek, “Soot nanostructure: dependence upon synthesis conditions,” Combust. Flame 136(1-2), 129–140 (2004).\n[Crossref]\n\nK. Yehliu, R. L. Vander Wal, and A. L. Boehman, “Development of an HRTEM image analysis method to quantify carbon nanostructure,” Combust. Flame 158(9), 1837–1851 (2011).\n[Crossref]\n\nB. Apicella, P. Pré, J. N. Rouzaud, J. Abrahamson, R. L. V. Wal, A. Ciajolo, A. Tregrossi, and C. Russo, “Laser-induced structural modifications of differently aged soot investigated by HRTEM,” Combust. Flame 204, 13–22 (2019).\n[Crossref]\n\n#### Fuel (2)\n\nB. Apicella, A. Ciajolo, A. Tregrossi, J. Abrahamson, R. L. Vander Wal, and C. Russo, “HRTEM and EELS investigations of flame-formed soot nanostructure,” Fuel 225, 218–224 (2018).\n[Crossref]\n\nU. Trivanovic, T. A. Sipkens, M. Kazemimanesh, A. Baldelli, A. M. Jefferson, B. M. Conrad, M. R. Johnson, J. C. Corbin, J. S. Olfert, and S. N. Rogak, “Morphology and size of soot from gas flares as a function of fuel and water addition,” Fuel 279, 118478 (2020).\n[Crossref]\n\n#### Int. J. Heat Mass Transfer (2)\n\nF. Liu, B. J. Stagg, D. R. Snelling, and G. J. Smallwood, “Effects of primary soot particle size distribution on the temperature of soot particles heated by a nanosecond pulsed laser in an atmospheric laminar diffusion flame,” Int. J. Heat Mass Transfer 49(3-4), 777–788 (2006).\n[Crossref]\n\nK. J. Daun, “Thermal accommodation coefficients between polyatomic gas molecules and soot in laser-induced incandescence experiments,” Int. J. Heat Mass Transfer 52(21-22), 5081–5089 (2009).\n[Crossref]\n\n#### J. Aerosol Sci. (2)\n\nP. Roth and A. V. Filippov, “In situ ultrafine particle sizing by a combination of pulsed laser heatup and particle thermal emission,” J. Aerosol Sci. 27(1), 95–104 (1996).\n[Crossref]\n\nA. V. Filippov, M. W. Markus, and P. Roth, “In-situ characterization of ultrafine particles by laser-induced incandescence: sizing and particle structure determination,” J. Aerosol Sci. 30(1), 71–87 (1999).\n[Crossref]\n\n#### J. Colloid Interface Sci. (1)\n\nA. V. Filippov, M. Zurita, and D. E. Rosner, “Fractal-like Aggregates: Relation between Morphology and Physical Properties,” J. Colloid Interface Sci. 229(1), 261–273 (2000).\n[Crossref]\n\n#### J. Comput. Appl. Math. (1)\n\nJ. Kaipio and E. Somersalo, “Statistical inverse problems: Discretization, model reduction and inverse crimes,” J. Comput. Appl. Math. 198(2), 493–504 (2007).\n[Crossref]\n\n#### J. Heat Transfer (1)\n\nT. Sipkens, G. Joshi, K. J. Daun, and Y. Murakami, “Sizing of molybdenum nanoparticles using time-resolved laser-induced incandescence,” J. Heat Transfer 135, 549–557 (2013).\n[Crossref]\n\n#### J. Phys. Chem. C (2)\n\nH. A. Michelsen, “Understanding and predicting the temporal response of laser-induced incandescence from carbonaceous particles,” J. Phys. Chem. C 118(15), 7012–7045 (2003).\n[Crossref]\n\nT. A. Sipkens and K. J. Daun, “Effect of Surface Interatomic Potential on Thermal Accommodation Coefficients Derived from Molecular Dynamics,” J. Phys. Chem. C 122(35), 20431–20443 (2018).\n[Crossref]\n\n#### J. Quant. Spectrosc. Radiat. Transfer (1)\n\nJ.-W. Shi, H. Qi, J.-Y. Zhang, Y.-T. Ren, L.-M. Ruan, and Y. Zhang, “Simultaneous measurement of flame temperature and species concentration distribution from nonlinear tomographic absorption spectroscopy,” J. Quant. Spectrosc. Radiat. Transfer 241, 106693 (2020).\n[Crossref]\n\n#### Nat. Geosci. (1)\n\nV. Ramanathan and G. Carmichael, “Global and regional climate changes due to black carbon,” Nat. Geosci. 1(4), 221–227 (2008).\n[Crossref]\n\n#### Opt. Commun. (1)\n\nJ.-Y. Zhang, H. Qi, Y.-T. Ren, and L.-M. Ruan, “Simultaneous identification of optical constants and PSD of spherical particles by multi-wavelength scattering–transmittance measurement,” Opt. Commun. 413, 317–328 (2018).\n[Crossref]\n\n#### Proc. Combust. Inst. (5)\n\nH. A. Michelsen, “Probing soot formation, chemical and physical evolution, and oxidation: A review of in situ diagnostic techniques and needs,” Proc. Combust. Inst. 36(1), 717–735 (2017).\n[Crossref]\n\nB. F. Kock, T. Eckhardt, and P. Roth, “In-cylinder sizing of diesel particles by time-resolved laser-induced incandescence (TR-LII),” Proc. Combust. Inst. 29(2), 2775–2782 (2002).\n[Crossref]\n\nT. Lehre, R. Suntz, and H. Bockhorn, “Time-resolved two-color LII: size distributions of nano-particles from gas-to-particle synthesis,” Proc. Combust. Inst. 30(2), 2585–2593 (2005).\n[Crossref]\n\nB. F. Kock, C. Kayan, J. Knipping, H. R. Orthner, and P. Roth, “Comparison of LII and TEM sizing during synthesis of iron particle chains,” Proc. Combust. Inst. 30(1), 1689–1697 (2005).\n[Crossref]\n\nP. Desgroux, X. Mercier, and K. A. Thomson, “Study of the formation of soot and its precursors in flames using optical diagnostics,” Proc. Combust. Inst. 34(1), 1713–1738 (2013).\n[Crossref]\n\n#### Prog. Energy Combust. Sci. (1)\n\nH. A. Michelsen, C. Schulz, G. J. Smallwood, and S. Will, “Laser-induced incandescence: Particulate diagnostics for combustion, atmospheric, and industrial applications,” Prog. Energy Combust. Sci. 51, 2–48 (2015).\n[Crossref]\n\n#### Other (3)\n\nK. Daun, F. Liu, and G. Smallwood, “Molecular dynamics simulations of translational thermal accommodation coefficients for time-resolved LII,” in Heat Transfer Summer Conference, 2008), 333–342.\n\nD. Colton and R. Kress, Inverse acoustic and electromagnetic scattering theory (Springer Nature, 2019), Vol. 93.\n\nC. F. Bohren and D. R. Huffman, Absorption and scattering of light by small particles (John Wiley & Sons, 2008).\n\n### Cited By\n\nOSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.\n\n### Figures (8)\n\nFig. 1. Schematic of underlying heat and mass transfer processes involved in LII\nFig. 2. Flowchart of double-model inversion process\nFig. 3. Effects of different laser fluences on temperature and diameter decay rate of primary particles when Np = 1 and dp = 10 nm\nFig. 4. (a) when Np = 1 and dp = 10 nm and (b) when Np = 600 and dp = 150 nm, the effect of different laser fluence on the ratio of the energy sum of laser absorption and heat conduction to the total energy\nFig. 5. Noisy LII signals synthesized by (a) the general noise model and (b) Gaussian model\nFig. 6. Primary particle size distribution profiles derived from retrieval results of (a) Gaussian noise and (b) general noise cases in Table 2 together with the target value\nFig. 7. Log contours of the objective function on (a) σd, g - dp, g plane, (b) αT, f - dp, g plane, and αT, f - σd, g plane\nFig. 8. Logarithmic objective function of valley lines of Fig. 6 along the coordinate axes\n\n### Tables (3)",
null,
"Table 1. Basic settings of the test cases",
null,
"Table 2. Retrieval results of three objective parameters in 8 test cases",
null,
"Table 3. Retrieval results of three two-variable inversions\n\n### Equations (26)\n\n$Q ˙ int = Q ˙ abs + Q ˙ cond + Q ˙ rad + Q ˙ sub + Q ˙ therm + Q ˙ ox + Q ˙ ann$\n$M ˙ = M ˙ sub + M ˙ ox$\n$Q ˙ int = N p c s ρ s π 6 d p 3 d T d t$\n$Q ˙ abs = N p C abs E ( t ) = N p C abs F q ( t )$\n$C abs = π 2 d p 3 E ( m ) λ inc$\n$Q ˙ cond = − π N p d p 2 α T P a 8 8 R m T δ π W a ( γ ∗ + 1 γ ∗ − 1 ) ( T T δ − 1 )$\n$N p = k f ( 2 R g d p ) D f$\n$Q ˙ cond = − π D eff 2 α T P a 8 8 R m T δ π W a ( γ ∗ + 1 γ ∗ − 1 ) ( T T δ − 1 )$\n$Q ˙ int = Q ˙ abs + Q ˙ cond$\n$d T d t = 6 π c s ρ s d p 3 [ C abs F q ( t ) ⏟ Absorption − π d p 2 η α T P a 8 8 R m T δ π W a ( γ ∗ + 1 γ ∗ − 1 ) ( T T δ − 1 ) ⏟ heat conduction ]$\n$α T, f ≡ η ⋅ α T$\n$f obj = ‖ b mea − b est b mea ‖ 2 2$\n$b mea = b tar ( 1 + γ ) n G$\n$b mea = b tar + τ n b tar ⏟ Shot - to - shot error + [ θ ( 1 + τ n ) b tar ] 1 / 2 ∘ n P ⏟ Poisson error + γ n G ⏟ Gaussian error$\n$F ref = λ inc ρ s c s ( T ref − T g ) 6 π E ( m )$"
] | [
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https://planetmath.org/companionmatrix | [
"# companion matrix\n\nGiven a monic polynomial $p(x)=x^{n}+a_{n-1}x^{n-1}+\\dots+a_{1}x+a_{0}$ the companion matrix",
null,
"",
null,
"of $p(x)$, denoted $\\mathcal{C}_{p(x)}$, is the $n\\times n$ matrix with $1$’s down the first subdiagonal and minus the coefficients of $p(x)$ down the last column, or alternatively, as the transpose",
null,
"",
null,
"of this matrix. Adopting the first convention this is simply\n\n $\\mathcal{C}_{p(x)}=\\begin{pmatrix}0&0&\\ldots&\\ldots&\\ldots&-a_{0}\\\\ 1&0&\\ldots&\\ldots&\\ldots&-a_{1}\\\\ 0&1&\\ldots&\\ldots&\\ldots&-a_{2}\\\\ 0&0&\\ddots&&&\\vdots\\\\ \\vdots&\\vdots&&\\ddots&&\\vdots\\\\ 0&0&\\ldots&\\ldots&1&-a_{n-1}\\end{pmatrix}.$\n\nRegardless of which convention is used the minimal polynomial",
null,
"",
null,
"(http://planetmath.org/MinimalPolynomialEndomorphism) of $\\mathcal{C}_{p(x)}$ equals $p(x)$, and the characteristic polynomial",
null,
"",
null,
"",
null,
"of $\\mathcal{C}_{p(x)}$ is just $(-1)^{n}p(x)$. The $(-1)^{n}$ is needed because we have defined the characteristic polynomial to be $\\det(\\mathcal{C}_{p(x)}-xI)$. If we had instead defined the characteristic polynomial to be $\\det(xI-\\mathcal{C}_{p(x)})$ then this would not be needed.\n\nTitle companion matrix CompanionMatrix 2013-03-22 13:17:12 2013-03-22 13:17:12 aoh45 (5079) aoh45 (5079) 7 aoh45 (5079) Definition msc 15A21"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.79442436,"math_prob":0.99986017,"size":897,"snap":"2020-10-2020-16","text_gpt3_token_len":221,"char_repetition_ratio":0.1343785,"word_repetition_ratio":0.03125,"special_character_ratio":0.25975475,"punctuation_ratio":0.09803922,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.999785,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18],"im_url_duplicate_count":[null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-03-29T22:28:55Z\",\"WARC-Record-ID\":\"<urn:uuid:b1b86e9f-4a00-4acd-a39a-4e5d7b0ecd87>\",\"Content-Length\":\"14553\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:e3815d65-29ce-4696-8e47-ed7925e67694>\",\"WARC-Concurrent-To\":\"<urn:uuid:4c97bc4a-e933-46da-a48b-2c351ec6efd2>\",\"WARC-IP-Address\":\"129.97.206.129\",\"WARC-Target-URI\":\"https://planetmath.org/companionmatrix\",\"WARC-Payload-Digest\":\"sha1:L74CBWKANMY5LEDSZMDKJDQKZATLLIPA\",\"WARC-Block-Digest\":\"sha1:G7VLZN5PZM7ZWFUZULI4XEP3XMSPLXIW\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-16/CC-MAIN-2020-16_segments_1585370496227.25_warc_CC-MAIN-20200329201741-20200329231741-00548.warc.gz\"}"} |
https://fr.mathworks.com/matlabcentral/cody/problems/1323-alternating-sum/solutions/1584708 | [
"Cody\n\n# Problem 1323. Alternating sum\n\nSolution 1584708\n\nSubmitted on 16 Jul 2018 by Ankith Rathod\nThis solution is locked. To view this solution, you need to provide a solution of the same size or smaller.\n\n### Test Suite\n\nTest Status Code Input and Output\n1 Pass\nx=508; assert(isequal(altsum(x),508))\n\ny = 0 y = 508\n\n2 Pass\nx=[1692 591]; assert(isequal(altsum(x),1101))\n\ny = 0 y = 1692 y = 1101\n\n3 Pass\nx=[-644 380 1009]; assert(isequal(altsum(x),-15))\n\ny = 0 y = -644 y = -1024 y = -15\n\n4 Pass\nx=[-20 -48 0 -318]; assert(isequal(altsum(x),346))\n\ny = 0 y = -20 y = 28 y = 28 y = 346\n\n5 Pass\nx=[1095 -1874 428 896 731 578 40]; assert(isequal(altsum(x),2694))\n\ny = 0 y = 1095 y = 2969 y = 3397 y = 2501 y = 3232 y = 2654 y = 2694"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.5101087,"math_prob":0.9998679,"size":717,"snap":"2020-34-2020-40","text_gpt3_token_len":308,"char_repetition_ratio":0.18092567,"word_repetition_ratio":0.05185185,"special_character_ratio":0.57322174,"punctuation_ratio":0.12048193,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99953413,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-08-15T20:19:08Z\",\"WARC-Record-ID\":\"<urn:uuid:45240546-d558-4870-8e35-c015d0ae0dbb>\",\"Content-Length\":\"74890\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:085729e8-5ff2-4fc9-87a1-5e197f869572>\",\"WARC-Concurrent-To\":\"<urn:uuid:0e4fc003-0d17-4d4a-89d0-9ccdf000bbd5>\",\"WARC-IP-Address\":\"23.212.144.59\",\"WARC-Target-URI\":\"https://fr.mathworks.com/matlabcentral/cody/problems/1323-alternating-sum/solutions/1584708\",\"WARC-Payload-Digest\":\"sha1:NCBTQBRQDRLSSDH4QVGWVYI3GEXU5LXB\",\"WARC-Block-Digest\":\"sha1:GVSSMFIIS62LYCEHF4NOWWCG2EANZT5N\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-34/CC-MAIN-2020-34_segments_1596439741154.98_warc_CC-MAIN-20200815184756-20200815214756-00278.warc.gz\"}"} |
https://proofwiki.org/wiki/Category:Combinations | [
"# Category:Combinations\n\nThis category contains results about Combinations.\n\nLet $S$ be a set containing $n$ elements.\n\nAn $r$-combination of $S$ is a subset of $S$ which has $r$ elements.\n\n## Subcategories\n\nThis category has only the following subcategory.\n\n## Pages in category \"Combinations\"\n\nThis category contains only the following page."
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.80148983,"math_prob":0.8903689,"size":448,"snap":"2021-43-2021-49","text_gpt3_token_len":104,"char_repetition_ratio":0.21396397,"word_repetition_ratio":0.06451613,"special_character_ratio":0.203125,"punctuation_ratio":0.0945946,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9844672,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-12-08T16:19:35Z\",\"WARC-Record-ID\":\"<urn:uuid:9afc9b72-da83-4116-ad50-1a95f63d3669>\",\"Content-Length\":\"35042\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:414ac55a-9924-4d9e-967d-af447efdbf90>\",\"WARC-Concurrent-To\":\"<urn:uuid:eb1f483d-9d6c-4d09-9ec4-69d641f5dbce>\",\"WARC-IP-Address\":\"104.21.84.229\",\"WARC-Target-URI\":\"https://proofwiki.org/wiki/Category:Combinations\",\"WARC-Payload-Digest\":\"sha1:7DPRLXMNBQIKXU6SIULKU5MPMT6VGLYS\",\"WARC-Block-Digest\":\"sha1:DXMWMQG4TDJ6FAZB3ODRNRKTARFCFWYS\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-49/CC-MAIN-2021-49_segments_1637964363515.28_warc_CC-MAIN-20211208144647-20211208174647-00246.warc.gz\"}"} |
https://timsong-cpp.github.io/cppwp/n4861/temp.constr.normal | [
"# 13 Templates [temp]\n\n## 13.5 Template constraints [temp.constr]\n\n### 13.5.3 Constraint normalization [temp.constr.normal]\n\nThe normal form of an expression E is a constraint that is defined as follows:\n• The normal form of an expression ( E ) is the normal form of E.\n• The normal form of an expression E1 || E2 is the disjunction of the normal forms of E1 and E2.\n• The normal form of an expression E1 && E2 is the conjunction of the normal forms of E1 and E2.\n• The normal form of a concept-id C<A, A, ..., A> is the normal form of the constraint-expression of C, after substituting A, A, ..., A for C's respective template parameters in the parameter mappings in each atomic constraint. If any such substitution results in an invalid type or expression, the program is ill-formed; no diagnostic is required.\nExample\n:\n```template<typename T> concept A = T::value || true;\ntemplate<typename U> concept B = A<U*>;\ntemplate<typename V> concept C = B<V&>;\n```\nNormalization of B's constraint-expression is valid and results in T::value (with the mapping ) true (with an empty mapping), despite the expression T::value being ill-formed for a pointer type T. Normalization of C's constraint-expression results in the program being ill-formed, because it would form the invalid type V&* in the parameter mapping. — end example\n]\n• The normal form of any other expression E is the atomic constraint whose expression is E and whose parameter mapping is the identity mapping.\nThe process of obtaining the normal form of a constraint-expression is called normalization.\nNote\n:\nNormalization of constraint-expressions is performed when determining the associated constraints ([temp.constr.constr]) of a declaration and when evaluating the value of an id-expression that names a concept specialization ([expr.prim.id]).\n— end note\n]\nExample\n:\n```template<typename T> concept C1 = sizeof(T) == 1;\ntemplate<typename T> concept C2 = C1<T> && 1 == 2;\ntemplate<typename T> concept C3 = requires { typename T::type; };\ntemplate<typename T> concept C4 = requires (T x) { ++x; }\n\ntemplate<C2 U> void f1(U); // #1\ntemplate<C3 U> void f2(U); // #2\ntemplate<C4 U> void f3(U); // #3\n```\nThe associated constraints of #1 are sizeof(T) == 1 (with mapping ) 1 == 2.\n\nThe associated constraints of #2 are requires { typename T::type; } (with mapping ).\n\nThe associated constraints of #3 are requires (T x) { ++x; } (with mapping ).\n— end example\n]"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.66464895,"math_prob":0.9657561,"size":502,"snap":"2021-21-2021-25","text_gpt3_token_len":131,"char_repetition_ratio":0.1124498,"word_repetition_ratio":0.0,"special_character_ratio":0.24103586,"punctuation_ratio":0.14432989,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9968448,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2021-05-06T13:55:24Z\",\"WARC-Record-ID\":\"<urn:uuid:0325a11a-cff8-450f-8af6-69296c8e8b5b>\",\"Content-Length\":\"18430\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:5fff8abd-db07-44e2-8a66-78b5021a84de>\",\"WARC-Concurrent-To\":\"<urn:uuid:06848bc5-b40c-44db-a32f-f3ce60e147b3>\",\"WARC-IP-Address\":\"185.199.109.153\",\"WARC-Target-URI\":\"https://timsong-cpp.github.io/cppwp/n4861/temp.constr.normal\",\"WARC-Payload-Digest\":\"sha1:XSUML57CWYFJNUA5J5G7QR7Q5RM23VZC\",\"WARC-Block-Digest\":\"sha1:V3OVXT2YRN3I6MHG7KERERKI5LQRJGKH\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2021/CC-MAIN-2021-21/CC-MAIN-2021-21_segments_1620243988753.97_warc_CC-MAIN-20210506114045-20210506144045-00218.warc.gz\"}"} |
https://it.mathworks.com/matlabcentral/cody/problems/1046-add-two-numbers | [
"Cody\n\n# Problem 1046. Add two numbers\n\nCalculate the sum of two numbers.\n\nExample\n\n``` input = [2 3]\noutput = 5```\n\n### Solution Stats\n\n65.15% Correct | 34.85% Incorrect\nLast Solution submitted on Jun 04, 2020"
] | [
null
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https://ctms.engin.umich.edu/CTMS/index.php?aux=Activities_LRCcircuitA | [
"Effects\nTips\n\n# Activity 2 Part (a): Time-Response of an Inductor–Resistor–Capacitor (LRC) Circuit",
null,
"Key Topics: Modeling Electrical Systems, Underdamped Second-Order Systems, System Identification\n\n## Equipment needed\n\n• Arduino board (e.g. Uno, Mega, etc.)\n• Battery (AA for example)\n• Electronic components (inductor, resistor, capacitor)\n• Switch (pushbutton, or can employ a transistor)\n• Jumper wires\n\nThe system we will be employing in this activity is a simple electrical circuit consisting of an inductor (L), a resistor (R), and a capacitor (C) in series. The Arduino board will be used for measuring the output of this LRC circuit and possibly for triggering the input to the circuit. The input to the circuit will be a voltage step, supplied by a battery through a push-button switch, applied across all three components in series. The output of the circuit will be the voltage across the capacitor, which will be read via one of the board's Analog Inputs. This data is then fed to Simulink for visualization and for comparison to our resulting simulation model output.\n\n## Purpose\n\nThe purpose of this activity is to demonstrate how to model a simple electrical system. Specifically, a first-principles approach based on the underlying physics of the circuit will be employed. The associated experiment is employed to determine the accuracy of the resulting model and to demonstrate how the individual circuit components affect the response. This activity also provides a physical example of the common class of (underdamped) second-order systems.\n\n## Modeling from first principles\n\nFirst we will employ our understanding of the underlying physics of the LRC circuit to derive the structure of the system model. We will term this process \"modeling from first principles.\" In this example, we employ the variables shown below. In textbooks, the various components of a circuit are often treated as \"ideal.\" It is important to know when such idealized models can be employed (and when they can't). In this experiment we will include the resistance contributed by our inductor (termed the inductor's equivalent series resistance (ESR)) because it will turn out to be significant. Specifically, we will employ a rather large inductor in order to achieve an underdamped step response. Such large inductors commonly have significant ESR, though lower ESR inductors exist if you are willing to spend more money! Capacitors also contribute resistance, but the associated ESR won't be significant for the size of capacitor we will ultimately employ. Later we will also briefly discuss the simplification of treating a transistor as an ideal switch.\n\n(R) resistance of the resistor\n(L) inductance of the inductor\n(Req) equivalent series resistance (ESR) of the inductor\n(C) capacitance of the capacitor\n(ei) input voltage\n(eo) output voltage",
null,
"To begin, we assume a direction for the current and then apply Kirchoff’s Voltage Law (loop law). Current flows from a higher potential to a lower potential, therefore, the direction of the current will be clockwise in this case (shown below).",
null,
"The loop law states that the sum of voltages around a closed loop must equal zero. Thus, the loop law produces the following governing equation for the circuit.\n\n(1)",
null,
"An alternative to an integro-differential equation model of a dynamic system is the transfer function. The transfer function captures the input/output behavior of a system and is derived by first taking the Laplace transform of a given integro-differential equation, while assuming zero initial conditions (",
null,
").\n\n(2)",
null,
"Next we must perform some algebra to rearrange the above into the form of its output divided by its input. In this case, our input is",
null,
"and our output is",
null,
". Therefore, we must eliminate current",
null,
"from the above since it is neither an input nor an output, and we must introduce the output",
null,
"into the above equation. Solving the above equation for",
null,
"we arrive at the following.\n\n(3)",
null,
"Next we can recognize that the output voltage (across the capacitor) is",
null,
". Taking the Laplace transform and again solving for",
null,
", we arrive at the following.\n\n(4)",
null,
"Setting the two previous equations equal to one another, we can eliminate",
null,
".\n\n(5)",
null,
"Then re-arranging into the desired form of output divided by input, we produce the resulting transfer function model.\n\n(6)",
null,
"Recognizing the above as a second-order system, we can manipulate the transfer function so that it has the standard, canonical form shown below.\n\n(7)",
null,
"In this form we can see by inspection how the parameters of the circuit affect its transient response (though not the steady-state response). Specifically, the circuit components affect the parameters of the canonical second-order system in the following manner.\n\n(8)",
null,
"(9)",
null,
"(10)",
null,
"These relations then relate to the characteristics of an underdamped second-order step response. Note, the DC gain is 1 no matter the choice of component values.\n\n## System identification experiment\n\nIn this experiment we will record the output voltage of the LRC circuit for a step in input voltage. We then will compare the data to the response predicted by the first-principles derived model we created previously.\n\nHardware setup\n\nOur simple LRC circuit can be implemented on a breadboard and connected to the Arduino board for recording the output voltage. There are different techniques for generating our voltage \"step\" input. We will specifically employ a battery as our voltage source with a push-button switch. The act of completing the circuit with the switch is equivalent to applying a step input. Driving the circuit with one of the Arduino board's Digital Outputs is problematic for a couple of reasons. For one, the Digital Output from the board provides a 5-Volt step input. This means that if the circuit is underdamped, then the output voltage will overshoot 5 Volts since the DC gain is 1. This overshoot would cause the output voltage to exceed the allowed range of the Analog Input. This could be alleviated by employing a different circuit configuration, but there is another issue. Switching the inductive load can make it difficult for the Digital Output to generate a true step, since the voltage tends to get pulled down. The same issue can arise with the 3.3 Volt source on the board. Employing a battery (AA for example) with a switch avoids these issues. The nominal voltage for most alkaline household batteries (AAA, AA, D, etc.) is 1.5 Volts.",
null,
"The setup of the LRC circuit and its connection to the Arduino board is shown below. The biggest challenge to achieving an underdamped response (",
null,
") that is not too fast for the Arduino board to sample (",
null,
"not too large) is to employ an inductor with sufficient inductance but not too much ESR. We will employ a 1",
null,
"inductor with 40",
null,
"ESR that was relatively inexpensive to purchase. We will also employ a 510",
null,
"capacitor and a 10",
null,
"resistor, though this resistor is not necessary (make sure it is not too large). These components provide a damping ratio of",
null,
". One thing to note is that if you employ an electrolytic capacitor, its orientation matters. Specifically, if your capacitor has legs of different lengths and one leg is marked by a negative sign, then you have an electrolytic capacitor. Orient an electrolytic capacitor so that the leg marked by the negative sign connects to the lower potential part of the circuit (ground in this case). The Arduino board is employed to acquire the output voltage data from the circuit (via an Analog Input) and communicates the data to Simulink.",
null,
"Software setup\n\nIn this experiment, we will employ Simulink to read the data from the board and to plot the data in real time. In particular, we will employ the IO package from the MathWorks. For details on how to use the IO package, refer to the following link. The Simulink model we will use is shown below and can be downloaded here, where you may need to change the port to which the Arduino board is connected (the port is COM3 in this case).\n\nAs shown below, this Simulink model simply reads the output voltage of the LRC circuit. Specifically, the Arduino Analog Read block reads the output voltage data via the Analog Input A0 on the board. Double-clicking on the block allows us to set the Pin to 0 from the drop-down menu. We also will set the Sample Time. Referring to the earlier equations and the nominal component values,",
null,
"rad/sec. Since",
null,
", this means that",
null,
"rad/sec. Therefore, we will expect a peak time for our step response of approximately",
null,
"seconds. In order to clearly capture the transient response of the circuit, we will choose our sampling time to be 0.01 seconds. This sampling period is close to the limit of what the IO package can achieve running under the Windows operating system, but is necessary to reconstruct this particular step response accurately. The downloadable model included above defines all sample times as Ts (or left as \"-1\"). Therefore, before you run this model you must define the variable Ts in the MATLAB workspace by typing Ts = 0.01; at the command line.",
null,
"The other blocks in the model can also be set to have a sample time of Ts. The Gain block is included to convert the data into units of Volts (by multiplying the data by 5/1023). This conversion can be understood by recognizing that the Arduino Board employs a 10-bit analog-to-digital converter, which means (for the default) that an Analog Input channel reads a voltage between 0 and 5 V and slices that range into",
null,
"pieces. Therefore, 0 corresponds to 0 V and 1023 corresponds to 5 V. The given Simulink model then plots the recorded output voltage on a scope and also writes the output data to the MATLAB workspace for further analysis. The Arduino Analog Read block, the Arduino IO Setup block, and the Real-Time Pacer block are all part of the IO package. The remaining blocks are part of the standard Simulink library, specifically, they can be found under the Math and Sinks libraries.\n\nRecall that the \"step input\" to our LRC circuit is generated employing a push button as described earlier. Therefore, once you begin the model running, you will need to press the push button to cause the input voltage to step. One such set of data is shown below. Note that this data is for the case that the capacitor initially has no charge. If you are performing successive runs and wish to begin with an initial output voltage of zero, then you will need to discharge the capacitor before performing a run. This can be done by simply shorting (placing a wire between) the two legs of the capacitor.",
null,
"In the next section we will compare this data to the response predicted by our previously derived first-principle's model.\n\n## Model validation\n\nAt this point we will now use the MATLAB command step to generate the step response predicted by the first-principles model generated earlier. The transfer function version of this model is repeated below.\n\n(11)",
null,
"In order to facilitate the comparison between the predicted and collected data, we will shift the recorded data so that the step occurs at time",
null,
"seconds (step appears to occur at time equal to 1.22 seconds). Furthermore, we will scale the predicted response to account for the fact that the input is not a unit step. Based on the steady-state value of the recorded data, it appears the battery's voltage is approximately 1.53 Volts (the battery voltage in this example is negligibly affected by changes in the load).\n\nApplying the following MATLAB commands, where the output of our Simulink model from above eo is saved as a time series, will generate the plot shown below.\n\n s = tf('s');\nR = 10; % resistor resistance\nReq = 40; % inductor equivalent series resistance (ESR)\nL = 1; % inductor inductance\nC = 510*10^-6; % capacitor capacitance\nei = 1.53; % battery voltage\ntstep = 1.22; % time step occurred\nG = 1/(C*L*s^2 + C*(R+Req)*s + 1); % model transfer function\n[y,t] = step(G*ei,0.5); % model step response with battery voltage scaling\nplot(t,y)\nhold\nplot(eo.Time(100*tstep:100*tstep+50)-tstep,eo.Data(100*tstep:100*tstep+50),'r:') % experimental data\nxlabel('time (sec)')\nylabel('output voltage (Volts)')\ntitle('LRC Circuit Step Response')\nlegend('model','experiment','Location','SouthEast')",
null,
"Examining the above, the predicted and actual responses are similar, though not exactly the same. The primary contributor to this is likely variation in the component values from their nominal labeled values. Since the actual peak time is greater than predicted, this indicates that",
null,
"is smaller than predicted since",
null,
". Since the overshoot is slightly larger than predicted, that would indicate",
null,
"is smaller than anticipated. Taken together, this also indicates",
null,
"is smaller than anticipated since",
null,
". From prior analysis, we have the following.\n\n(12)",
null,
"(13)",
null,
"Therefore, it is possible that the product of the capacitor's capacitance and the inductor's inductance is larger than indicated (explaining",
null,
"). It is also possible that inductance is larger than anticipated, or that the resistances and capacitance are smaller than predicted (explaining",
null,
").\n\nOther factors besides the variation in the system component values could also explain the difference between the observed response and that predicted by the model. Specifically unmodeled dynamics, variation in sampling time, and the input not being a perfect step could contribute. One significant source of unmodeled dynamics is the loading effect of the channel that is reading the output voltage. In other words, the channel itself does not have infinite impedance.\n\n## Alternative implementation\n\nIn the above experiment we generated our \"step\" input using a battery and a push-button switch. If you would like more control over the timing of this input step, you can instead use a Digital Output from the Arduino board to trigger the step using a transistor as a switch.\n\nA circuit for achieving this implementation is shown below that employs a MOSFET transistor where the pins for the Gate, Source, and Drain are identified. One possible choice of power MOSFET is the IRF1520 whose datasheet can be found here. The circuit is set up this way for two reasons. For one, it is desirable to connect the source S to ground because that limits the level of voltage needed to trigger the transistor at the gate G. In other words, the potential difference between the gate G and the source S needs to cross a threshold to fully switch the transistor \"ON\" (to create a low resistance connection between the drain D and the source S). The transistor we employ here has a threshold between 2 and 4 Volts. The other reason is that in this configuration when the transistor is \"ON\" and behaving as a closed switch, then there is little current flowing to the capacitor so that it does not build up much charge. For the transistor we employ here, in the \"ON\" state it has a resistance between the drain and source of approximately 0.2",
null,
". This resistance is much smaller than the ESR of the inductor (overall impedance much smaller too), therefore, most of the current will flow through the transistor and not the path with the capacitor. For example, we could generate a step response like we did with the push button in the following manner. First we set the Digital Output from the Arduino board high (5 Volts) to close the transistor switch. This causes most of the battery current to flow through the path with the transistor and will allow the capacitor to discharge if it has charge built up on it. We can then set the Digital Output from the board low (0 Volts) to open the transistor switch. When that occurs, most all of the current from the battery flows through the series LRC circuit and it is as if the input voltage from the battery has been stepped.",
null,
"A wiring example showing the connections to the Arduino Board and the orientation of the MOSFET is shown below.",
null,
"In order to generate the Digital Output from the Arduino board, the Simulink model created earlier needs to be modified to include a Digital Write block and a Pulse Generator block as shown below. The Digital Write block is set to output on Pin 9, while the Pulse Generator block is set to output 1 for the first second of the run (in order to discharge the capacitor) then the output switches to 0 which causes the current to the LRC circuit to \"step.\" The model shown below can be can be downloaded here.",
null,
"The result of running this model is shown below where the capacitor initially has charge built up because the transistor switch was \"open\" while the MOSFET was not being triggered.",
null,
"Executing the following MATLAB code in the command window will generate the step response predicted by our first principles model and plot it next to the actual experimental data, where the output of our Simulink model from above, eo, is saved as a time series.\n\n s = tf('s');\nR = 10; % resistor resistance\nReq = 40; % inductor equivalent series resistance (ESR)\nL = 1; % inductor inductance\nC = 510*10^-6; % capacitor capacitance\nei = 1.5; % battery voltage\nG = 1/(C*L*s^2 + C*(R+Req)*s + 1); % model transfer function\n[y,t] = step(G*ei,0.5); % model step response with battery voltage scaling\nplot(t,y)\nhold\nplot(eo.Time(101:151)-1.01,eo.Data(101:151),'r:') % experimental data\nxlabel('time (sec)')\nylabel('output voltage (Volts)')\ntitle('LRC Circuit Step Response')\nlegend('model','experiment','Location','SouthEast')",
null,
"Examination of the above demonstrates a similar level of agreement between the experiment and the prediction as was achieved with the push-button switch. More accurate measurement of the circuit components would achieve better agreement between the model and the experimental data.\n\n## Extensions\n\nAlternate LRC circuits can be examined to investigate the modeling of circuits that are not canonical first-order or second-order systems. Specifically, the effect of zeros and higher-order poles can be examined. One can also employ variable resistors (potentiometers) or variable capacitors to examine the effect of different parameters. In Part (b) of this activity, an RC circuit is added in series with the LRC circuit examined here.",
null,
""
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https://bmcmedresmethodol.biomedcentral.com/articles/10.1186/1471-2288-10-20 | [
"# Variables with time-varying effects and the Cox model: Some statistical concepts illustrated with a prognostic factor study in breast cancer\n\n## Abstract\n\n### Background\n\nThe Cox model relies on the proportional hazards (PH) assumption, implying that the factors investigated have a constant impact on the hazard - or risk - over time. We emphasize the importance of this assumption and the misleading conclusions that can be inferred if it is violated; this is particularly essential in the presence of long follow-ups.\n\n### Methods\n\nWe illustrate our discussion by analyzing prognostic factors of metastases in 979 women treated for breast cancer with surgery. Age, tumour size and grade, lymph node involvement, peritumoral vascular invasion (PVI), status of hormone receptors (HRec), Her2, and Mib1 were considered.\n\n### Results\n\nMedian follow-up was 14 years; 264 women developed metastases. The conventional Cox model suggested that all factors but HRec, Her2, and Mib1 status were strong prognostic factors of metastases. Additional tests indicated that the PH assumption was not satisfied for some variables of the model. Tumour grade had a significant time-varying effect, but although its effect diminished over time, it remained strong. Interestingly, while the conventional Cox model did not show any significant effect of the HRec status, tests provided strong evidence that this variable had a non-constant effect over time. Negative HRec status increased the risk of metastases early but became protective thereafter. This reversal of effect may explain non-significant hazard ratios provided by previous conventional Cox analyses in studies with long follow-ups.\n\n### Conclusions\n\nInvestigating time-varying effects should be an integral part of Cox survival analyses. Detecting and accounting for time-varying effects provide insights on some specific time patterns, and on valuable biological information that could be missed otherwise.\n\n## Background\n\nSurvival analysis, or time-to-event data analysis, is widely used in oncology since we are often interested in studying a delay, such as the time from cancer diagnosis or treatment initiation to cancer recurrence or death. Thanks to the improvement of cancer treatments, and the induced longer life expectancy, we observe an increasing number of studies with long follow-up periods. Statistical models to analyze such data should thus adequately account for the increasing duration of follow-ups. The Cox proportional hazards (PH) model allows one to describe the survival time as a function of multiple prognostic factors . This model relies on a fundamental assumption, the proportionality of the hazards, implying that the factors investigated have a constant impact on the hazard - or risk - over time. If time-dependent variables are included without appropriate modeling, the PH assumption is violated. As a result, misleading effect estimates can be derived, and significant effect in the early (or late) follow-up period may be missed. Checking the proportionality of the hazards should thus be an integral part of a survival analysis by a Cox model. The assumption, however, is not systematically verified. In a 1995 review of cancer publications using a Cox model, Altman et al. reported that most studies did not report verifying this assumption ; similar findings were reported recently by one of the co-authors of the present work .\n\nAlthough the Cox model has been widely used (more than 25 000 citations since the publication of the original paper by Cox ), recent publications suggest a growing interest in the quality of its applications. Special papers in statistics have been published in the oncology literature providing general introductions to survival analysis ; topics covered included summarizing survival data, testing for a difference between groups, presenting existing statistical models, or assessing the adequacy of a survival model. Others works focused on providing definition of specific survival endpoints , or on the quality of reporting of survival events .\n\nAssessing whether the assumption of proportional hazards is a central theme in survival analysis, and as such is discussed in several statistical textbooks as well as in the general statistical literature . To our knowledge however, this topic has been discussed in few medical journals. Importantly, this strong assumption does not seem to be systematically assessed. For illustration, a recent review of clinical trials with primary analyses based on survival end points showed that only one of the 64 papers that used a Cox model mentioned verifying the PH assumption .\n\nOur objective is to inform clinicians, as well as those who read and write manuscripts in medical journals, about the importance of the underlying PH assumption, the misleading conclusions that can be inferred if it is violated, as well as the additional information provided by verifying it. After a theoretical introduction, we describe techniques to assess if this assumption is violated, and model strategies to account for, and describe time-dependency. We illustrate our discussion with a study on prognostic factors in breast cancer.\n\n## Methods and results\n\n### Survival analysis\n\nIn many studies, the primary variable of interest is a delay, such as the time from cancer diagnosis to a particular event of interest. This event may be death, and for this reason the analysis of such data is often referred to as survival analysis. The event of interest may not have occurred at the time of the statistical analysis, and similarly, a subject may be lost to follow-up before the event is observed. In such case, data are said to be censored at the time of the analysis or at the time the patient was lost to follow-up. Censored data still bring some information since although we do not know the exact date of the event, we know that it occurred later than the censoring time.\n\nBoth the Kaplan-Meier method and the Cox proportional hazards (PH) model allow one to analyze censored data [1, 19], and to estimate the survival probability, S(t), that is the probability that a subject survives beyond some time t. Statistically, this probability is provided by the survival function S(t) = P (T > t), where T is the survival time. The Kaplan Meier method estimates the survival probability non-parametrically, that is, assuming no specific underlying function . Several tests are available to compare the survival distributions across groups, including the log-rank and the Mann-Whitney-Wilcoxon tests [20, 21]. The Cox PH model accounts for multiple risk factors simultaneously. It does not posit any distribution, or shape for the survival function, however, the instantaneous incidence rate of the event is modeled as a function of time and risk factors.\n\nThe instantaneous hazard rate at time t, also called instantaneous incidence, death, or failure rate, or risk, is the instantaneous probability of experiencing an event at time t, given that the event has not occurred yet. It is a rate of event per unit of time, and is allowed to vary over time. Just as the risk of events per unit time, one can make an analogy by considering the speed given by a car speedometer, which represents the distance travelled per unit of time. Suppose, that the event of interest is death, and we are interested in its association with n covariates, X1, X2, ..., Xn, then the hazard is given by:",
null,
"(1)\n\nThe baseline hazard rate h0(t) is an unspecified non-negative function of time. It is the time-dependent part of the hazard and corresponds to the hazard rate when all covariate values are equal to zero. β1, β2, ..., βn are the coefficients of the regression function β1x1 + β2x2 +... βnxn. Suppose that we are interested in a single covariate then the hazard is:",
null,
"(2)\n\nThe hazards for two subjects with covariate values x1 and x2 are thus given respectively by hx1(t) = h0(t) exp(βx1) and hx2(t) = h0(t) exp(βx2), and the hazard ratio is expressed as:",
null,
"(3)\n\nTaking x2 = x1 + 1, the hazard ratio reduces to HR = exp(β) and corresponds to the effect of one unit increase in the explanatory variable X on the risk of event. Since β = log(HR), β is referred as the log hazard ratio. Although the hazard rate hx(t) is allowed to vary over time, the hazard ratio HR is constant; this is the assumption of proportional hazards. If the HR is greater than 1 (β > 0), the event risk is increased for subjects with covariate value x2 compared to subjects with covariate value x1, while a HR lower than 1 (β < 0) indicates a decreased risk. When the HR is not constant over time, the variable is said to have a time-varying effect; for example, the effect of a treatment can be strong immediately after treatment but fades with time. This should not be confused with a time-varying covariate, which is a variable whose value is not fixed over time, such as smoking status. Indeed, a person can be a non-smoker, then a smoker, then a non-smoker. Note however, that a variable may be both time-varying and have an effect that changes over time.\n\nIn a Cox PH model, the HR is estimated by considering each time t at which an event occurs. When estimating the overall HR over the complete follow-up period, the same weights are given to the very early HR which affect almost all individuals and to very late HR affecting only the very few individuals still at risk. The HR is thus averaged over the event times. In the case of proportional hazards, the overall HR is not affected by this weighting procedure. If, on the other hand, the HR changes over time, that is, the hazard rates are not proportional, then equal weighting may result in a non-representative HR, and may produce biased results . It should be noted that the HR is averaged over the event times rather than over the follow-up time. It is unchanged if the time scale is changed without disturbing the ordering of events.\n\n### Example\n\nWe applied some of the presented methods to breast cancer patients as time-varying effects have been reported, such as for nodal or hormone receptor status, . We studied women with non-metastatic, operable breast cancer who underwent surgery between 1989 and 1993 at our institution, and who did not receive previous neoadjuvant treatment. Exclusion criteria included a previous history of breast carcinoma, concurrent contralateral breast cancer, and pathologic data missing. Follow-up was performed according to the European Good Clinical Practice requirements and consisted of regular physical examinations, and annual X-ray mammogram, and additional assessments in case of suspected metastases. Clinical and pathological characteristics were analyzed according to the hospital-recorded file at the time of treatment initiation. Pathological tumour size (≤ or > 20 mm) was measured on fresh surgical specimens. A modified version of the Scarff-Bloom-Richardson grading system was used (SBR grade I, II, or III). PVI (Yes, No) was defined as the presence of neoplastic emboli within unequivocal vascular lymphatic or capillary lumina in areas adjacent to the breast tumour. Exploratory immuno-histochemical analyses were performed on a tissue microarray (TMA) to assess hormone receptor (HRec) status (positive if ER-positive and/or progesterone receptor [PgR]-positive). ER and PgR expression levels were evaluated semi-quantitatively according to a standard protocol with cut-off values at 10% positive tumor cells. Her2 expression level was evaluated according to the Herceptest scoring system . Mib1 expression level was evaluated semi-quantitatively. Information on all factors was available for 979 women (Table 1). The median follow-up time was 14 years (95% confidence interval: 13.7 - 14.2) and 264 women developed metastases.\n\n#### Working example\n\nThe prognostic factors were initially selected based on current knowledge regarding risk of metastases. They were next analyzed using a conventional Cox regression model; all were statistically significant at the 5% level in the univariate analyses, and were then entered onto a multivariate Cox model. The risk of metastases was increased for women with younger age compared to older age; grade II and III tumours compared to grade I tumours; large compared to small tumour sizes; lymph node involvement compared to no involvement; and PVI compared to no PVI (Additional file 1: Estimated log hazard ratios (log(HR)), and hazard ratios (HR = exp(",
null,
")) with 95% confidence intervals (95% CI) and p-values for model covariates when fitting a multivariate conventional Cox model and a Cox model with time-by-covariate interactions.). Based on this model, all variables, but hormone receptor, Her2 and Mib1 status, significantly affected the risk of metastases.\n\n### Assessing non-proportionality: Graphical strategy\n\nIn the presence of a categorical variable, one can plot the Kaplan-Meier survival distribution, S(t), as a function of the survival time, for each level of the covariate. If the PH assumption is satisfied, the curves should steadily drift apart. One can also apply a transformation of the Kaplan-Meier survival curves and plot the function log(-log(S(t))) as a function of the log survival time, where log represents the natural logarithm function. If the hazards are proportional, the stratum specific log-minus-log plots should exhibit constant differences, that is be approximately parallel. These visual methods are simple to implement but have limitations. When the covariate has more than two levels, Kaplan-Meier plots are not useful for discerning non-proportionality because the graphs become to cluttered . Similarly, although the PH assumption may not be violated, the log-minus-log curves are rarely perfectly parallel in practice, and tend to become sparse at longer time points, and thus less precise. It is not possible to quantify how close to parallel is close enough, and thus how proportional the hazards are. The decision to accept the PH hypothesis often depends on whether these curves cross each other. As a result, the decision to accept the PH hypothesis can be subjective and conservative , since one must have strong evidence (crossing lines) to conclude that the PH assumption is violated. In view of these limitations, some suggest providing standard errors to these plots . This approach however can be computationally intensive and is not directly available in standard computer programs. Kaplan-Meier and log-minus-log plots are available from most standard statistical packages (Table 2).\n\n#### Working example (cont')\n\nKaplan-Meier survival curves and log-minus-log plots are shown for some variables (Figures 1 and 2). The Kaplan-Meier survival curves appeared to steadily drift apart for all but the hormone receptor status, Her2 status, and mib1 status. The log-minus log plots looked approximately parallel for Age, size of the tumour, lymph node involvement, and PVI. Again, plots for the hormone receptor status, Her2 status, and mib1 status tended to indicate a violation of the PH assumption. There was also some suspicion with respect to the SBR grade.\n\n### Assessing non-proportionality: Modelling and testing strategies\n\nGraphical methods for checking the PH assumption do not provide a formal diagnostic test, and confirmatory approaches are required. Multiple options for testing and accounting for non-proportionality are available.\n\nCox proposed assessing departure from non-proportionality by introducing a constructed time-dependent variable, that is, adding an interaction term that involves time to the Cox model, and test for its significance . Suppose one is interested in evaluating if some variable X has a time-varying effect. A time-dependent variable is created by forming an interaction (product) term between the predictor, X (continuous or categorical), and a function of time t (f(t) = t, t2, log(t), ...). Adding this interaction to the model (equation 2), the hazard then becomes:",
null,
"(5)\n\nThe hazard ratio is given by HR(t) = hx+1(t)/hx(t) = exp[β + γ.x.f(t)] for a unit increase in the variable X, and is time-dependent through the function f(t). If γ > 0 (γ < 0), then the HR increases (decreases) over time. Testing for non-proportionality of the hazards is equivalent to testing if γ is significantly different from zero. One can use different time functions such as polynomial or exponential decay but often very simple fixed functions of time such as linear or logarithmic functions are preferred . This modeling approach also provides estimates of the hazard ratio at different time points since values t of time can be fitted into the hazard ratio function. Time-dependent variables provide a flexible method to evaluate departure from non-proportionality and an approach to building a model for the dependence of relative risk over time. This approach however should be used with caution. Indeed, if the function of time selected is mis-specified, the final model will not be appropriate. This is a disadvantage of this method over more flexible approach.\n\n#### Working example (cont')\n\nWe created time-by-covariate interactions for each variable of the model, by introducing products between the variables and a linear function of time. As shown in Additional File 1 (Estimated log hazard ratios (log(HR)), and hazard ratios (HR = exp(",
null,
")) with 95% confidence intervals (95% CI) and p-values for model covariates when fitting a multivariate conventional Cox model and a Cox model with time-by-covariate interactions.), significant time-by-covariate interactions involved the SBR grade, hormone receptor status, Her2 status, and PVI (p < 0.05). Thus these results indicated that the hazard ratios associated with these factors were not constant over time. The parameters (",
null,
") associated with most interactions were negative, suggesting that the hazard ratios were decreasing over time. The estimated hazard ratio associated with an SBR grade II (versus grade I) as a function of time t was given by: HR(t) = exp(1.71 - 0.14t). Hazard ratios were 4.8, 3.6, and 2.7 at respectively 1, 3, and 5 years. Similarly, the estimated hazard ratio associated with the hormone receptor status was: HR(t) = exp(0.73 - 0.14t), that is hazard ratios of 1.8, 1.3, and 1.0 at respectively 1, 3, and 5 years. While the conventional Cox model did not show any significant effect for hormone receptors, Her2 and Mib1, these variables had a significant effect once time-by-covariate interactions were included.\n\nDeparture from non-proportionality can also be investigated using the residuals of the model. A residual measures the difference between the observed data, and the expected data under the assumption of the model. Schoenfeld residuals are calculated and reported at every failure time under the PH assumption, and as such are not defined for censored subjects [15, 30]. They are defined as the covariate value for the individual that failed minus its expected value assuming the hypotheses of the model hold. There is a separate residual for each individual for each covariate. A smooth plot of the Schoenfeld residuals can then be used to directly visualize the log hazard ratio . Assuming proportionality of the hazards, the Schoenfeld residuals are independent of time. Thus, a plot suggesting a non-random pattern against time is evidence of non-proportionality. Graphically, this method is more reliable and easier to interpret than plotting the log(-log(S(t)) function presented earlier. The presence of a linear relationship with time can be tested by performing a simple linear regression and a test trend. A slope significantly different from zero would be evidence against proportionality: an increasing (decreasing) trend would indicate an increasing (decreasing) hazard ratio over time. It is recommended to carefully look at the residual plot in addition to performing this test as some patterns may be apparent on the plots (quadratic, logarithmic), but remain undetected by the statistical test. Moreover, undue influence of outliers might become obvious . Although, the method based on the smoothed Schoenfeld residuals provides time-dependent estimates, it can have some drawbacks [14, 18]. The uncertainty estimates associated with the resulting time-dependent estimates can be difficult to use in practice, and the estimator provided may not have good statistical properties, such as consistency. Importantly, p-values resulting from trend tests based on the Schoenfeld residuals are obtained independently for each covariate of the model, assuming the Cox model is justified for the other covariates of the model; as such, results should be interpreted carefully. Tests based on the Schoenfeld residuals can be easily implemented in most standard statistical packages (Table 2).\n\n#### Working example (cont')\n\nFor each covariate, scaled Schoenfeld residuals were plotted over time, and tests for a zero slope were performed. The corresponding p-values, as well as the p-value associated with a global test of non-proportionality are reported in Table 3. The global test suggested strong evidence of non-proportionality (p < 0.01). Variables that deemed most likely to contribute to non-proportionality were the SBR grade (p < 0.01), PVI (p = 0.05) and hormone receptor status (p = 0.05). These numerical findings suggest a non constant hazard ratio for these variables. Residuals help visualizing the log hazard ratio",
null,
"over time for each covariate (figure 3). We added dashed and dotted lines representing respectively the null effect (null log hazard ratio) and the averaged log hazard ratio estimated by the conventional Cox model. With respect to the SBR grade, the plots suggested strong effect over the first five years. This effect tended to diminish afterwards. Similarly, the impact of PVI changed over time, with again higher risks of metastases in the early years, and then this effect tended to vanish. Concerning hormone receptor status, plots suggested that a negative status increased the risk of metastases early on, and became protective afterwards.\n\nThe cumulative sum of Schoenfeld residuals, or equivalently the observed score process can also be used to assess proportional hazards . Graphically, the observed score process is plotted versus time for each variable of the model, together with simulated processes assuming the underlying Cox model is true, that is, assuming proportional hazards. Any departure of the observed score process from the simulated ones is evidence against proportionality. These plots can then be used to assess when the lack of fit is present. In particular, an observed score well above the simulated process is an indication of an effect higher than the average one, and conversely. This method is particularly well illustrated in a recent publication by Cortese et al. . Goodness-of-fit tests can be implemented based on the cumulative residuals. The cumulative residuals based approach overcomes some drawbacks encountered with the Schoenfeld residuals, since resulting estimators tend to have better statistical properties, and justified p-values are derived . The cumulative residuals approach is implemented in some standard statistical packages (Table 2).\n\n#### Working example (cont')\n\nTests based on cumulative residuals are presented in Table 4. At the 5% significance level, test statistics suggest non-constant effect over time for the grade of the tumor, as well as the status of the hormone receptors, her2, and Mib1. For illustration, we also plotted the resulting score process for some variables (Figure 4). In accordance with the test statistics based on the cumulative residuals, we observe strong departure of the observed processes from the simulated curves under the model for the grade and hormone receptor status. These plots are particularly useful in identifying where the lack of fit is present. For example, the initial positive score process associated with hormone receptors, suggests that the effect of this variable is initially higher than the average effect, and thus lower than the average effect afterwards. That is, the risk of metastases is increased initially for women with both negative hormone receptors compared to the average risk, and decreased afterwards.\n\nAnother simple approach for testing time-varying effects of covariates involves fitting different Cox models for different time periods. Indeed, although the PH assumption may not hold over the complete follow-up period, it may hold over a shorter time window. Unless there is an interest in a particular cut-off time value, two subsets of data can be created based on the median event time . That is, a first analysis is conducted by censoring everyone still at risk beyond this time point, and a second one by considering only those subjects still at risk thereafter. In such case, the interpretation of the models is conditional on the length of the survival time, and results should thus be interpreted with caution. Even if the period of analysis is shortened, one should still ensure that the PH assumption is not violated within these reduced time periods. Moreover, since fewer event times are considered, analyses can suffer from a decreased power. Finally, although this method is particularly simple to implement and might provide sufficient information in some settings, that is if one is interested in a short time window, it should be noted that this method is not directly testing the PH assumption, and a different parametrization would be needed to perform such a test.\n\n#### Working example (cont')\n\nThe median event time was 4.3 years. A Cox model was applied censoring everyone still at risk after 4.3 years, while only those subjects still at risk beyond this time point were included in another model (Additional file 2: Estimated hazard ratios (exp(",
null,
")) with 95% confidence intervals (95% CI) and p-values for model covariates in two independent Cox models for two different time periods.). All variables but age were statistically significant in the first model as negative hormone receptor status, positive Her2 status and Mib1 positive status were associated with an increased risk of metastases. In women still at risk past 4.3 years, younger age, greater tumor size, and lymph node involvement were associated with an increased risk of metastases. The effects of other variables have disappeared. Interestingly, hormone receptor negative status had a significant protective effect in this second model (HR = 0.5), while the first analysis suggested a significant increased risk for (HR = 1.7). Tests for non-proportionality based on the cumulative residuals suggested a persistent time-varying effect of the grade for the analysis restricted to the first 4.3 years.\n\nIt is also possible to account for non-proportionality by partitioning the time axis as proposed by Moreau et al. . The time axis is partitioned and hazard ratios are then estimated within each interval. Thus, testing for non-proportionality is equivalent to testing if the time-specific HR are significantly different. Results can however sometimes be driven by the number of time intervals , and time intervals should thus be carefully selected.\n\nAbandoning the assumption of proportional hazards, and as such, the Cox model, is another option. Indeed, other powerful statistical models are available to account for time-varying effects, including additive models, accelerated failure time models, regression splines models or fractional polynomials .\n\nFinally, one can perform a statistical analysis stratified by the variable suspected to have a time-varying effect; this variable should be thus categorical or be categorized. Each stratum k has a distinct baseline hazard but common values for the coefficient vector β, that is, the hazard for an individual in stratum k is hk(t) = exp(βx) Stratifying assumes that the other covariates are acting in the same way in each stratum, that is, HRs are similar across strata. Although stratification is effective in removing the problem of non-proportionality and simple to implement, it has some disadvantages. Most importantly, stratification by a non-proportional variable precludes estimation of its strength and its test within the Cox model. Thus, this approach should be selected if one is not directly interested in quantifying the effect of the variable used for stratification. Moreover, a stratified Cox model can lead to a loss of power, because more of the data are used to estimate separate hazard functions; this impact will depend on the number of subjects and strata . If there are several variables with time-varying risks, this would require the model to be stratified on these multiple factors, which again is likely to decrease the overall power.\n\n## Discussion\n\nWhile ensuring that the PH assumption holds is part of the modeling process, it is also useful in providing valuable information on time-varying effects. In our illustrative example, the conventional Cox model suggested that all factors but HRec, Her2, and Mib1 status were strong prognostic factors of metastases. Additional tests indicated that the PH assumption was not satisfied for some variables of the model. Tumour grade had a significant time-varying effect, but although its effect diminished over time, it remained strong. According to the conventional model hormone receptor status did not significantly impact relapses. Additional tests provided strong evidence of a time-varying effect. Importantly, both tests based on residuals suggested that negative hormone receptor status increased the risk of metastases early but became protective thereafter, in accordance with the analysis partitioned on event time. This reversal of effect may explain the non-significant averaged hazard ratio provided by the conventional Cox model and reported earlier .\n\nApplying a Cox model without ensuring that its underlying assumptions are validated can lead to negative consequences on the resulting estimates [28, 37]. For variables not satisfying the non-proportionality assumption, the power of the corresponding tests is reduced, that is, we are less likely to conclude for a significant effect when there is actually one. If the hazard ratio is increasing over time, the estimated coefficient assuming PH is overestimating at first and underestimating later on. For those variables of the model with a constant hazard ratio, the power of tests is also reduced as a consequence of an inferior fit of the model.\n\nOnce non-proportionality is established, time-dependency can be accounted for in different ways. The strategy will depend on the study objectives. If there is no interest in longer time periods, one can shorten the follow-up time as non-proportionality is less likely to be an issue on short time intervals. If there is no particular interest in the variable with the time-varying effect, one could stratify on this variable in the statistical analysis, however no association between the stratification variable and survival can be tested. If one wants to describe the effect of the variable over time, it is possible to rely on time by covariate interactions or on plots of residuals to estimate of relative risks at different time points. Methods to test and account for non-proportionality are available in most standard statistical software (Table 2).\n\nIt is difficult to propose definite guidelines for the best strategy for testing for non-proportionality. Each method has its advantages and limitations, and depending on the study objective some approaches might be preferred. Before performing statistical modeling, the study objectives should be clearly stated in advance, as well as the statistical tests that will be employed. Departure from non-proportionality can be investigated using graphical and numerical approaches. Plotting methods involve visualizing the Kaplan-Meier survival curves for the variable tested for non-proportionality. This graphical method requires categorical variables, and is particularly appropriate for binary data; however they do not provide formal diagnostic tests. Numerical tests involve for example testing for covariate-by-time interactions or for the presence of a trend in the residuals of the model. Including a covariate-by-time interaction is particularly simple within the Cox model; however, results are strongly dependent on the choice of the functional form of the time function. Tests based on cumulative residuals tend to have better statistical properties than those based on the Schoenfeld residuals. As a result, performing a test based on the cumulative residuals seems to be a more powerful approach in detecting covariates with time-varying effects.\n\nNote that the Cox model involves multiple types of residuals including the martingale, deviance, score and Schoenfeld residuals, which can be particularly useful as additional regression diagnostics for the Cox model. Martingale residuals are useful for determining the functional form of a covariate to be included in the model and deviance residuals can be used to examine model accuracy. Additional details can be found in [10, 11].\n\nStatistical testing raises the issue of power, that is, the ability of tests to find true effects. We have seen for example that some simple strategies, such as shortening the observation period can suffer from reduced power as fewer events are considered. This might be a limitation with small datasets. Simulations have shown that stratified Cox modeling usually leads to wider confidence intervals, that is, reduced power compared to unstratified analysis . Statistical tests for time-varying effects have different power to detect non-proportionality. It has been shown that tests requiring partitioning of the failure time have less power than other tests, while tests based on time-dependent covariates or on the Schoenfeld residuals have equally good power to detect non-proportionality in a variety of non-proportional hazards and are practically equivalent . The issue of power naturally leads to the question of sample size. Clinical trials are usually designed with just enough power to detect the treatment effect. In this context, one should not expect to have enough details about the actual shape of the HR over time. Assuming a trial designed with an 80% power to detect a treatment effect, Therneau and Grambsch showed that the test based on the residuals was able to detect non-proportionality, but could not distinguish between a linear and a discrete increase of the hazard ratio over time . Observational studies are usually designed for exploratory analyses and do not rely on a formal estimation of the sample size. There might not always be enough power to detect a specific time trend. The question of lack of power should not be interpreted as an argument against testing for non-proportionality. Just as any other statistical model, one should ensure that major assumptions are not violated.\n\nSince its original publication in 1972, the Cox proportional-hazards model has gained widespread use and has become a popular tool for the analysis of survival data in medicine. After performing an online search, we found that the original paper by Cox had been cited approximately 25, 000 times, with about 8, 000 citations in oncology papers . While time dependency has been accounted for and reported in oncology publications, such as in breast or colon cancer studies [26, 33, 3942, 42], the verification of the PH assumption is unfortunately far from being systematic. In a 1995 review of five clinical oncology journals including about 130 papers, Altman et al. reported that only 2 out of the 43 papers which relied on a Cox model, mentioned that the PH assumption was verified . Similarly, about ten years later Mathoulin et al. assessed the quality of reporting of survival events in randomized clinical trials in eight general or cancer medical journals . The authors reported that only one of the 64 papers that used a Cox model mentioned verifying the PH assumption.\n\nOur objective was to familiarize the reader with the PH assumption. We also highlighted that detecting and accounting for time-varying effects provide insights on some specific time patterns and valuable biological information that could be missed otherwise. Given the possible consequences on parameter estimates, checking the proportionality of hazards should be an integral part of a survival analysis based on a Cox model. In the presence of variables with time-varying risks, plots should be used to augment the results and indicate where non-proportionality is present. This seems particularly appropriate in the context of oncology studies, as long follow-ups are common and non-constant hazards have already been reported.\n\n## Conclusions\n\nInvestigating time-varying effects should be an integral part of Cox survival analyses. Detecting and accounting for time-varying effects provide insights on some specific time patterns, and on valuable biological information that could be missed otherwise.\n\n## References\n\n1. 1.\n\nCox D: Regression Models and Life-Tables. Journal of the Royal Statistical Society, Series B. 1972, 34: 187-220.\n\n2. 2.\n\nAltman DG, De Stavola BL, Love SB, Stepniewska KA: Review of survival analyses published in cancer journals. Br J Cancer. 1995, 72: 511-8.\n\n3. 3.\n\nMathoulin-Pelissier S, Gourgou-Bourgade S, Bonnetain F, Kramar A: Survival end point reporting in randomized cancer clinical trials: a review of major journals. J Clin Oncol. 2008, 26: 3721-6. 10.1200/JCO.2007.14.1192.\n\n4. 4.\n\nISI Web of Knowledge. Web of Science Accessed Dec 1st, 2008. [http://apps.isiknowledge.com]\n\n5. 5.\n\nClark TG, Bradburn MJ, Love SB, Altman DG: Survival analysis part I: basic concepts and first analyses. Br J Cancer. 2003, 89: 232-8. 10.1038/sj.bjc.6601118.\n\n6. 6.\n\nBradburn MJ, Clark TG, Love SB, Altman DG: Survival analysis part II: multivariate data analysis--an introduction to concepts and methods. Br J Cancer. 2003, 89: 431-6. 10.1038/sj.bjc.6601119.\n\n7. 7.\n\nBradburn MJ, Clark TG, Love SB, Altman DG: Survival analysis Part III: multivariate data analysis -- choosing a model and assessing its adequacy and fit. Br J Cancer. 2003, 89: 605-11. 10.1038/sj.bjc.6601120.\n\n8. 8.\n\nClark TG, Bradburn MJ, Love SB, Altman DG: Survival analysis part IV: further concepts and methods in survival analysis. Br J Cancer. 2003, 89: 781-6. 10.1038/sj.bjc.6601117.\n\n9. 9.\n\nPunt CJ, Buyse M, Kohne CH, Hohenberger P, Labianca R, Schmoll HJ, et al: Endpoints in adjuvant treatment trials: a systematic review of the literature in colon cancer and proposed definitions for future trials. J Natl Cancer Inst. 2007, 99: 998-1003. 10.1093/jnci/djm024.\n\n10. 10.\n\nTherneau T, Grambsch P: Modelling Survival Data: Extending the Cox Model. 2000, New York, Springer\n\n11. 11.\n\nKlein JP, Moeschberger ML: Survival analysis. Techniques for censored and truncated data. 2003, New York, Springer\n\n12. 12.\n\nKalbfleisch JD, Prentice R: The statistical analysis of failure time data. 2002, New York, John Wiley & Sons, 2\n\n13. 13.\n\nLawless JF: Statistical models and methods for lifetime data. 1982, New York, John Wiley & Sons, Inc., 1\n\n14. 14.\n\nScheike T, Martinussen T: On Estimation and Tests of Time-Varying Effects in the Proportional Hazards Model. Scandinavian Journal of Statistics. 2004, 31: 51-62. 10.1111/j.1467-9469.2004.00372.x.\n\n15. 15.\n\nGrambsch P, Therneau T: Proportional Hazards Tests and Diagnostics Based on Weighted Residuals. Biometrika. 1994, 81: 515-26. 10.1093/biomet/81.3.515.\n\n16. 16.\n\nPutter H, Sasako M, Hartgrink HH, van d V, van Houwelingen JC: Long-term survival with non-proportional hazards: results from the Dutch Gastric Cancer Trial. Stat Med. 2005, 24: 2807-21. 10.1002/sim.2143.\n\n17. 17.\n\nNg'andu NH: An empirical comparison of statistical tests for assessing the proportional hazards assumption of Cox's model. Stat Med. 1997, 16: 611-26. 10.1002/(SICI)1097-0258(19970330)16:6<611::AID-SIM437>3.0.CO;2-T.\n\n18. 18.\n\nCortese G, Scheike T, Martinussen T: Flexible survival regression modelling. Stat Methods Med Res. 2009, 00: 1-24.\n\n19. 19.\n\nKaplan E, Meier P: Nonparametric Estimation from Incomplete Observations. J Am Stat Assoc. 1958, 53: 457-81. 10.2307/2281868.\n\n20. 20.\n\nGEHAN EA: A generalized Wilcoxon test for comparing arbitrarily singly-censored samples. Biometrika. 1965, 52: 203-23.\n\n21. 21.\n\nMantel N: Evaluation of survival data and two new rank order statistics arising in its consideration. Cancer Chemother Rep. 1966, 50: 163-70.\n\n22. 22.\n\nO'Quigley J, Pessione F: The problem of a covariate-time qualitative interaction in a survival study. Biometrics. 1991, 47: 101-15. 10.2307/2532499.\n\n23. 23.\n\nSaphner T, Tormey DC, Gray R: Annual hazard rates of recurrence for breast cancer after primary therapy. J Clin Oncol. 1996, 14: 2738-46.\n\n24. 24.\n\nHery M, Delozier T, Ramaioli A, Julien JP, de LB, Petit T, et al: Natural history of node-negative breast cancer: are conventional prognostic factors predictors of time to relapse?. Breast. 2002, 11: 442-8. 10.1054/brst.2002.0462.\n\n25. 25.\n\nArriagada R, Le MG, Dunant A, Tubiana M, Contesso G: Twenty-five years of follow-up in patients with operable breast carcinoma: correlation between clinicopathologic factors and the risk of death in each 5-year period. Cancer. 2006, 106: 743-50. 10.1002/cncr.21659.\n\n26. 26.\n\nHilsenbeck SG, Ravdin PM, de Moor CA, Chamness GC, Osborne CK, Clark GM: Time-dependence of hazard ratios for prognostic factors in primary breast cancer. Breast Cancer Res Treat. 1998, 52: 227-37. 10.1023/A:1006133418245.\n\n27. 27.\n\nHercepTest: 2008, Dako A/S G, Denmark: HercepTest package, [http://pri.dako.com/28630_herceptest_interpretation_manual.pdf]\n\n28. 28.\n\nSchemper M: Cox Analysis of Survival Data with Non-Proportional Hazard Functions. The Statistician. 1992, 41: 455-65. 10.2307/2349009.\n\n29. 29.\n\nMartinussen T, Thomas H: Dynamic Regression Models for Survival Data. 2006, New York, Springer\n\n30. 30.\n\nSchoenfeld D: chi-squared goodness if fit test for the proportional hazards regression model. Biometrika. 1981, 67: 147-53.\n\n31. 31.\n\nLin D, Wei L, Ying Z: Checking the Cox Model with Cumulative Sums of Martingale-Based Residuals. Biometrika. 1993, 80: 557-72. 10.1093/biomet/80.3.557.\n\n32. 32.\n\nMoreau T, O'Quigley J, Mesbah J: A Global Goodness-of-Fit Statistic for the Proportional Hazards Model. App Stat. 1985, 34: 212-8. 10.2307/2347465.\n\n33. 33.\n\nQuantin C, Abrahamowicz M, Moreau T, Bartlett G, MacKenzie T, Tazi MA, et al: Variation over time of the effects of prognostic factors in a population-based study of colon cancer: comparison of statistical models. Am J Epidemiol. 1999, 150: 1188-200.\n\n34. 34.\n\nAbrahamowicz M, MacKenzie T, Esdaile J: Time-Dependent Hazard Ratio: Modeling and Hypothesis Testing With Application in Lupus Nephritis. J Am Stat Assoc. 1996, 91: 1432-9. 10.2307/2291569.\n\n35. 35.\n\nAnderson WF, Chen BE, Jatoi I, Rosenberg PS: Effects of estrogen receptor expression and histopathology on annual hazard rates of death from breast cancer. Breast Cancer Res Treat. 2006, 100: 121-6. 10.1007/s10549-006-9231-y.\n\n36. 36.\n\nSauerbrei W, Royston P, Look M: A new proposal for multivariable modelling of time-varying effects in survival data based on fractional polynomial time-transformation. Biom J. 2007, 49: 453-73. 10.1002/bimj.200610328.\n\n37. 37.\n\nLagakos SW, Schoenfeld DA: Properties of proportional-hazards score tests under misspecified regression models. Biometrics. 1984, 40: 1037-48. 10.2307/2531154.\n\n38. 38.\n\nShepherd BE: The cost of checking proportional hazards. Stat Med. 2008, 27: 1248-60. 10.1002/sim.3020.\n\n39. 39.\n\nYoshimoto M, Sakamoto G, Ohashi Y: Time dependency of the influence of prognostic factors on relapse in breast cancer. Cancer. 1993, 72: 2993-3001. 10.1002/1097-0142(19931115)72:10<2993::AID-CNCR2820721022>3.0.CO;2-6.\n\n40. 40.\n\nGilchrist KW, Gray R, Fowble B, Tormey DC, Taylor SG: Tumor necrosis is a prognostic predictor for early recurrence and death in lymph node-positive breast cancer: a 10-year follow-up study of 728 Eastern Cooperative Oncology Group patients. J Clin Oncol. 1993, 11: 1929-35.\n\n41. 41.\n\nGore SD, Pocock SJ, Kerr G: Regression Models and Non-Proportional Hazards in the Analysis of Breast Cancer Survival. Applied Statistics. 1984, 33: 176-95. 10.2307/2347444.\n\n42. 42.\n\nBolard P, Quantin C, Esteve J, Faivre J, Abrahamowicz M: Modelling time-dependent hazard ratios in relative survival: application to colon cancer. J Clin Epidemiol. 2001, 54: 986-96. 10.1016/S0895-4356(01)00363-8.\n\n### Pre-publication history\n\n1. The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2288/10/20/prepub\n\n## Acknowledgements\n\nThe tissue microarray was financed by the Comités départementaux de la Gironde, Dordogne, Charente, Charente Maritime, Landes, by la Ligue Nationale contre le Cancer, and by Lyons Club de Bergerac, France.\n\n## Author information\n\nAuthors\n\n### Corresponding author\n\nCorrespondence to Carine A Bellera.\n\n### Competing interests\n\nThe authors declare that they have no competing interests.\n\n### Authors' contributions\n\nCB conceived the study, performed the statistical analysis and drafted the manuscript. GMG carried out the immunoassays. MD provided clinical expertise in oncology. CTL provided clinical expertise in surgery. VB was responsible of the datamanagement. SMP participated in the design of study. All authors read and approved the final manuscript.\n\n## Authors’ original submitted files for images\n\nBelow are the links to the authors’ original submitted files for images.\n\n## Rights and permissions\n\nReprints and Permissions\n\nBellera, C.A., MacGrogan, G., Debled, M. et al. Variables with time-varying effects and the Cox model: Some statistical concepts illustrated with a prognostic factor study in breast cancer. BMC Med Res Methodol 10, 20 (2010). https://doi.org/10.1186/1471-2288-10-20",
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null,
"https://bmcmedresmethodol.biomedcentral.com/track/article/10.1186/1471-2288-10-20",
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.91297144,"math_prob":0.8450424,"size":46541,"snap":"2020-45-2020-50","text_gpt3_token_len":10329,"char_repetition_ratio":0.1411565,"word_repetition_ratio":0.0799435,"special_character_ratio":0.2213962,"punctuation_ratio":0.13764434,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.9501222,"pos_list":[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20],"im_url_duplicate_count":[null,5,null,5,null,5,null,null,null,5,null,null,null,5,null,null,null,null,null,5,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2020-11-26T04:29:21Z\",\"WARC-Record-ID\":\"<urn:uuid:351e7003-d80f-4c6d-be22-ad625328cd20>\",\"Content-Length\":\"278692\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:7133ae75-2a5c-4803-a2e1-f7c0e6dfed65>\",\"WARC-Concurrent-To\":\"<urn:uuid:81e5ee1e-c665-43b3-a307-c61f9a26fdd0>\",\"WARC-IP-Address\":\"199.232.64.95\",\"WARC-Target-URI\":\"https://bmcmedresmethodol.biomedcentral.com/articles/10.1186/1471-2288-10-20\",\"WARC-Payload-Digest\":\"sha1:GFR5TRQKSZBBSEAOPYRXYKXX5ZX5L7AR\",\"WARC-Block-Digest\":\"sha1:TT5YJXV7A6D4MSMOIXD2X3EYTBZCHFWU\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2020/CC-MAIN-2020-50/CC-MAIN-2020-50_segments_1606141186414.7_warc_CC-MAIN-20201126030729-20201126060729-00410.warc.gz\"}"} |
http://civilservicereview.com/tag/multiplications-of-integer/ | [
"## Multiplications of Integers Quiz 1\n\nThis is a quiz on multiplication of integers. As we have learned, the following rules are applied in multiplication of integers.\n\na. positive x positive = positive\n\nb. positive x negative = negative\n\nc. negative x positive = negative\n\nd. negative x negative = positive.\n\nIn short, if the signs are the same, the product is positive. If the signs are different, the product is negative.\n\nGood luck!\n\nMultiplications of Integers Quiz 1",
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.81947696,"math_prob":0.99397236,"size":1581,"snap":"2019-51-2020-05","text_gpt3_token_len":443,"char_repetition_ratio":0.23715916,"word_repetition_ratio":0.18213059,"special_character_ratio":0.29222012,"punctuation_ratio":0.12328767,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99679434,"pos_list":[0,1,2],"im_url_duplicate_count":[null,null,null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-12-06T21:54:27Z\",\"WARC-Record-ID\":\"<urn:uuid:9094a811-e218-498b-8301-3e29c1d8e93f>\",\"Content-Length\":\"95551\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:b9d321f3-d263-45a4-8995-2ed17f9c7602>\",\"WARC-Concurrent-To\":\"<urn:uuid:3742d7ac-1e5f-4560-aa63-90b1ef77e594>\",\"WARC-IP-Address\":\"184.168.164.1\",\"WARC-Target-URI\":\"http://civilservicereview.com/tag/multiplications-of-integer/\",\"WARC-Payload-Digest\":\"sha1:UU245BQ42NIGIVKEIYTY3MCMI3NNY2YK\",\"WARC-Block-Digest\":\"sha1:ACEATQDRJ47SOYXPSNEU7DLPNF2KQDDG\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-51/CC-MAIN-2019-51_segments_1575540490972.13_warc_CC-MAIN-20191206200121-20191206224121-00081.warc.gz\"}"} |
https://uk.mathworks.com/matlabcentral/cody/problems/546-is-a-the-inverse-of-b/solutions/113578 | [
"Cody\n\n# Problem 546. Is A the inverse of B?\n\nSolution 113578\n\nSubmitted on 16 Jul 2012 by Jean-Marie Sainthillier\nThis solution is locked. To view this solution, you need to provide a solution of the same size or smaller.\n\n### Test Suite\n\nTest Status Code Input and Output\n1 Pass\n%% Test one A=[2,4;3,5]; B=[-2.5,2;1.5,-1]; y_correct = 1; assert(isequal(isInverse(A,B),y_correct))\n\n2 Pass\n%% Test two A=[1,2;3,5]; B=[-5,2;3,-1]; y_correct = 1; assert(isequal(isInverse(A,B),y_correct))"
] | [
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] | {"ft_lang_label":"__label__en","ft_lang_prob":0.5243581,"math_prob":0.96801114,"size":466,"snap":"2019-51-2020-05","text_gpt3_token_len":168,"char_repetition_ratio":0.12987013,"word_repetition_ratio":0.030303031,"special_character_ratio":0.41201717,"punctuation_ratio":0.24369748,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.95106983,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2019-12-10T21:15:20Z\",\"WARC-Record-ID\":\"<urn:uuid:080f9570-ef5d-47a1-b023-e666f3659676>\",\"Content-Length\":\"72906\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:6fe25b3c-3ed8-4a8c-b3fa-2e1559705faf>\",\"WARC-Concurrent-To\":\"<urn:uuid:0a89017c-2122-4eeb-b242-a41f7e4f1e4a>\",\"WARC-IP-Address\":\"104.117.0.182\",\"WARC-Target-URI\":\"https://uk.mathworks.com/matlabcentral/cody/problems/546-is-a-the-inverse-of-b/solutions/113578\",\"WARC-Payload-Digest\":\"sha1:PK5SKPBMVQLG7DWUO37RXPPC52XMY64Z\",\"WARC-Block-Digest\":\"sha1:ZG22J2MNYYLZQH76WP525PQCQ2VKVDCE\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2019/CC-MAIN-2019-51/CC-MAIN-2019-51_segments_1575540529006.88_warc_CC-MAIN-20191210205200-20191210233200-00455.warc.gz\"}"} |
https://www.python51.com/jc/10432.html | [
"## python中的坐标轴该如何画?好画吗?\n\n103次阅读\n\n1. 创建画布并引入axisartist工具。\n\n```import mpl_toolkits.axisartist as axisartist\n#创建画布\nfig = plt.figure(figsize=(8, 8))\n#使用axisartist.Subplot方法创建一个绘图区对象ax\nax = axisartist.Subplot(fig, 111)\n#将绘图区对象添加到画布中\n\n2. 绘制带箭头的x-y坐标轴\n\n```#通过set_visible方法设置绘图区所有坐标轴隐藏\nax.axis[:].set_visible(False)\n\n#ax.new_floating_axis代表添加新的坐标轴\nax.axis[\"x\"] = ax.new_floating_axis(0,0)\n#给x坐标轴加上箭头\nax.axis[\"x\"].set_axisline_style(\"->\", size = 1.0)\n#添加y坐标轴,且加上箭头\nax.axis[\"y\"] = ax.new_floating_axis(1,0)\nax.axis[\"y\"].set_axisline_style(\"-|>\", size = 1.0)\n#设置x、y轴上刻度显示方向\nax.axis[\"x\"].set_axis_direction(\"top\")\nax.axis[\"y\"].set_axis_direction(\"right\")```\n\n3. 在带箭头的x-y坐标轴背景下,绘制函数图像\n\n```#生成x步长为0.1的列表数据\nx = np.arange(-15,15,0.1)\n#生成sigmiod形式的y数据\ny=1/(1+np.exp(-x))\n#设置x、y坐标轴的范围\nplt.xlim(-12,12)\nplt.ylim(-1, 1)\n#绘制图形\nplt.plot(x,y, c='b')```"
] | [
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] | {"ft_lang_label":"__label__zh","ft_lang_prob":0.62064403,"math_prob":0.97345066,"size":1086,"snap":"2023-14-2023-23","text_gpt3_token_len":688,"char_repetition_ratio":0.13031423,"word_repetition_ratio":0.0,"special_character_ratio":0.28176796,"punctuation_ratio":0.24725275,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":0.99616355,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2023-03-30T17:36:42Z\",\"WARC-Record-ID\":\"<urn:uuid:6c617bda-b3fe-4697-b493-3b92ddc73bc1>\",\"Content-Length\":\"57494\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:2181e189-1460-4451-a61b-a37c73b7b3d4>\",\"WARC-Concurrent-To\":\"<urn:uuid:067cd5d3-9145-4304-9372-10856e68c6f2>\",\"WARC-IP-Address\":\"43.248.79.206\",\"WARC-Target-URI\":\"https://www.python51.com/jc/10432.html\",\"WARC-Payload-Digest\":\"sha1:MTHCN33JFLGFEI7XSUOY4OZR6B4CXQBJ\",\"WARC-Block-Digest\":\"sha1:EIXCO4MBOO3S76226VHJSOYKCBRAFUCW\",\"WARC-Identified-Payload-Type\":\"text/html\",\"warc_filename\":\"/cc_download/warc_2023/CC-MAIN-2023-14/CC-MAIN-2023-14_segments_1679296949355.52_warc_CC-MAIN-20230330163823-20230330193823-00446.warc.gz\"}"} |
https://softwareengineering.stackexchange.com/questions/254618/java-how-can-i-make-the-return-type-of-an-inherited-method-in-a-subclass-the | [
"# Java: how can I make the return type, of an inherited method in a subclass, the same as the subclass?\n\nI am rather inexperience in Java, and I'm having a problem in forming a subclass of a class I have created. The class I have made, called `Vector2D`, contains methods, such as `add(Vector2D addend)`, that takes a `Vector2D` object as an argument, and returns a `Vector2D` object. This method in particular is designed to add two vectors, and return the sum.\n\nThen, I started coding a subclass, called `Position2D`, which I intend to have all of the functionality of the `Vector2D` class, except have additional functions, and have any usage of `Vector2D` inside the preexisting classes, be it as an argument, return type, etc., replaced with `Position2D`, so that the `add(Position2D addend)` function adds two `Position2D` vectors together, and returns the sum as a `Position2D`.\n\nThe issue arises that, when `Position2D` inherits from `Vector2D`, such functions continue to work in terms of `Vector2D` objects, spitting out an error as soon as a `Position2D` object is passed through it.\n\nThe relevant code for the `Vector2D` class is as follows:\n\n``````public class Vector2D{\n\n//Field Variables\nprivate double x; //The vector's x-coordinate\nprivate double y; //The vector's y-coordinate\n\n//Constructors\npublic Vector2D(){\n//Constructs empty vector.\nsetX(0);\nsetY(0);\n}\n\n//Methods\npublic void setX(double newX){\n//This method is not problematic when inherited for the subclass.\nx = newX;\n}\n\npublic void setY(double newY){\n//This method is not problematic too.\ny = newY;\n}\n\n//Adds two vectors and returns the sum.\n//This method, however, does pose a problem.\nVector2D sum = new Vector2D();\nreturn sum;\n}\n\n}\n``````\n\nThe only work-around I can currently think of as to what the code in `add(Position2D addend)` in `Position2D` could be is:\n\n``````public Position2D add(Position2D addend){\n//Adds two position vectors and returns the sum.\nPosition2D sum = new Position2D();\nreturn sum;\n}\n``````\n\ni.e., repeat the method from `Vector2D`, and manually modify it. This, of course, is not efficient and wastes time, especially so whenever the same has to be done for similar methods, and more so whenever I intend to make more subclass, e.g. `Velocity2D`. Therefore, I am looking for a much cleaner and efficient means of doing this.\n\n• I think the problem here is that a point is not a vector. (Points and vectors are also not mutable but that's a different issue.) Aug 27, 2014 at 19:42\n• I don't think that's the issue at hand: I've defined both the \"Vector\" and \"Position\" class from scratch, and those are just names for the classes. I could have renamed them VectorA and VectorB, and the same issue arises. Aug 27, 2014 at 19:50\n• My point was that when things like this become an issue, it's usually because inheritance is being used for things that are not substitutes for the superclass. Yes, the same issue arises if you relate two arbitrary classes through inheritance, but that raises the question of why you're relating two arbitrary classes through inheritance. Aug 27, 2014 at 19:54\n• I see what you mean, but these classes don't seem arbitrary to me. I have defined a general vector class, and from that, I have intended to extend the functionality to more specific vectors, in this case, a position vector. From my understanding, a position vector should be a subclass of a vector: it is still a vector. Perhaps my use of the term \"position\" instead of \"position vector\" could have caused confusion? Aug 27, 2014 at 20:04\n• Adding points doesn't make sense as explained in the link; only adding displacement vectors makes sense. So if you mean to have points and vectors, the inheritance relationship doesn't hold because `add` isn't defined for points. If you have position vectors as you claim you do, then you already have those in the form of `Vector2D`; it makes no sense to create a separate type. If your intention is to distinguish between vectors with different units then you should probably be using generics so you can't add `Vector2D<Kilometers>` with `Vector2D<KilometersPerHour>`. Aug 28, 2014 at 0:21\n\nRemember inheritance defines a \"is a\" kind of relationship. The code\n\n`class Position2D extends Vector2D`\n\ntells the compiler that every Position2D is a Vector2D, but not vice versa.\n\nCheck out the following examples assuming that you already made the above declaration:\n\n``````// obviously okay, type of instance matches reference type\nVector2D vecVecRef = new Vector2D();\nPosition2D posPosRef = new Position2D();\n// this is okay because a Position2D is a Vector2D\nVector2D posVecRef = new Position2D();\n// The compiler will not automatically convert a Vector2D to a Position2D\nPosition2D vecPosRef = new Vector2D(); //Compiler error!\n``````\n\nA Position2D variable can never refer to a Vector2D object. If you try typecasting it, the compiler will say \"fine...I trust you\" but then the JVM will get angry when it actually finds out that you are trying to assign a Vector2D to a Position2D. It will raise a `ClassCastException` at runtime.\n\n``````// compiles fine but raises ClassCastException in runtime\nPosition2D vecPosRef = (Position2D) new Vector2D();\n``````\n\nThis is because you can only Class cast a subclass into a superclass and not vice versa. So basically, you cannot cast Vector2D to Position2D and you cannot assign it without casting either.\n\nThe simplest solution to this problem is to have a constructor defined in your subclass that makes a Position2D object out of a given Vector2D object.\n\n``````class Position2D extends Vector2D {\nPosition2D() {\n// default stuff\n}\n\nPosition2D(Vector2D v) {\n// you currently don't have the getX and getY methods\n// so define them in your superclass\nsetX(v.getX());\nsetY(v.getY());\n}\n}\n``````\n\nWith that one simple and convenient constructor, you can use code like this:\n\n``````public class Inheritance {\npublic static void main(String[] args) {\nPosition2D pos1 = new Position2D();\nPosition2D pos2 = new Position2D();\npos1.setX(3);\npos1.setY(4);\npos2.setX(5);\npos2.setY(6);\nPosition2D pos3 = new Position2D(pos1.add(pos2)); // using constructor\nSystem.out.println(pos3.getX()); // this prints 8.0\n}\n}\n``````\n\nAs you can see, this way is much more extensible than rewriting all of the subclass methods.\n\n• The super operator refers to the sub class of the base class. So, if you want to call setX or setY from the base class, then you would say super.setX and super.setY. It's a good idea to initialize the base class in the constructor of the sub class. You can do that by saying super(arg1, arg2, arg3, ...) Aug 27, 2014 at 20:53\n• In this case, calling the `super` constructor is redundant because Vector2D only has a default constructor and that constructor is implicitly called in every Position2D constructor anyways. Also, setX and setY haven't been overridden, so using super.setX and super.setY is also redundant. But yes, in the case of a constructor that uses parameters that are relevant to the superclass, you should use the `super` keyword to access the base class constructor with those arguments. Aug 27, 2014 at 21:26\n• The code works. In addition, looking at the line in your post (line 9 of Inheritance class): `Position2D pos3 = new Position2D(pos1.add(pos2));`, is it possible/good practice to essentially reduce that to `Position2D pos3 = pos1.add(pos2)` by adding the `= new Position2D(..)` portion of (line 9 of Inheritance class) into the `add(..)` function inside the `Position2D` class? Aug 27, 2014 at 22:23\n• @EternalCode It's certainly possible if you wish to avoid using that syntax, but in general, excessive overriding is bad practice. You already wrote an implementation of `add` that can do that in your opening post. But I was under the impression that you wanted to avoid doing stuff like that. If you really want to avoid it altogether, it's probably better practice to use interfaces as described in user61852's answer. Using an interface like `IVector2D`, a variable of type `IVector2D` can refer to any class that implements its methods. Aug 27, 2014 at 23:26\n• I see a problem with that solution. It assumes there is no additional state in the Position2D object. If for example Position2D had an additional flag to specify relative as compared to absolute position, that flag will get lost. And the user shouldn't have to know that the add() method belongs to a superclass and the result needs to be upgraded. Aug 30, 2014 at 15:56\n\nYou can by using the dependency inversion principle and the factory method pattern.\n\nThe return type should be a supertype of both `Vector2D` and `Position2D`.\n\nLet's call that `IVector2D` ( an interface ).\n\nThe solution would be:\n\n``````public interface IVector2D {\n\npublic void setX(double newX);\npublic void setY(double newY);\npublic double getX();\npublic double getY();\npublic IVector2D getInstance(); // this helps decouple the instantiation\n\n}\n``````\n\nAn then\n\n``````public class Vector2D implements IVector2D {\n\nprivate double x; //The vector's x-coordinate\nprivate double y; //The vector's y-coordinate\n\npublic Vector2D(){ setX(0); setY(0); }\n\npublic IVector2D getInstance(){ return new Vector2D(); }\n\n@Override\npublic void setX(double newX) { x = newX; }\n\n@Override\npublic void setY(double newY) { y = newY; }\n\n@Override\npublic double getX() { return this.x; }\n\n@Override\npublic double getY() { return this.y; }\n\n@Override\nIVector2D sum = getInstance();\nreturn sum;\n}\n}\n``````\n\nWhen extending, override `getInstance()` and implement a constructor:\n\n``````public class Position2D extends Vector2D {\npublic Position2D(){ super(); }\n@Override\npublic IVector2D getInstance(){ return new Position2D(); }\n}\n``````\n\nNote that you are actually returning an object of type `Position2D`, as you wanted, inside a reference of type `Ivector2D`, because you are overriding `getInstance()` and `add()` will call the `getInstance()` of `Position2D`. That abstraction allowed for the `add()` method to work seamlessly.\n\nThe test program would be:\n\n``````public static void main(String[] args) {\nIVector2D a = new Position2D();\nIVector2D b = new Position2D();\na.setX(1.2d);\na.setY(2.3d);\nb.setX(0.33d);\nb.setY(9.0d);\n``````1.53"
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https://file.scirp.org/Html/4803.html | [
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"Applied Mathematics, 2011, 2, 541-550 doi:10.4236/am.2011.25071 Published Online May 2011 (http://www.SciRP.org/journal/am) Copyright © 2011 SciRes. AM Pressure/Saturation System for Immiscible Two-Phase Flow: Uniqueness Revisited Koffi B. Fadimba University of South Carolina Aiken, Aiken, USA E-mail: SCKoffiF@usca.edu Received December 31, 2010; revised March 18, 2011; accepted March 21, 2011 Abstract We give a sufficient condition for uniqueness for the pressure/saturation system. We establish this condition through analytic arguments, and then construct “mobilities” (or mobility-like functions) that satisfy the new condition (when the parameter is 2). For the constructed “mobilities”, we do graphical experiments that show, empirically, that this condition could be satisfied for other values of 1< <2. These empirical experiments indicate that the usual smoothness condition on the fractional flow function (and on the total mobility), for uniqueness and convergence, might not be necessary. This condition is also sufficient for the convergence of a family of perturbed problems to the original pressure/saturation problem. Keywords: Porous Medium, Uniqueness of a Solution, Degenerate Equation, Immiscible Two-Phase Flow, Regularization, Phase Mobility. 1. Introduction Consider the coupled nonlinear problem (1), with , which arises from modeling incompre- ssible two-phase immiscible (water/oil, for example) flow through a porous medium (see [1,2], for instance). The problem considered, here, is in one of its simplified problem. 00Sx1The conductivity of the medium is denoted by k while u is the total Darcy's velocity for the two-phase flow, f is the fractional flow fun ction, S the saturation of the invading fluid (or wetting phase), P is the global pressure, and the porosity of the medium. For the present analysis and for simplicity, we let 1. The set is a sufficiently smooth bounded domain of , , 2 or 3, although this analysis focuses more on the case . nR=1n2n=Obviously, Problem 1 cannot, in general, be solved analytically: One needs to proceed through numerical approximations. Before attempting any solution method, one needs to investigate whether the problem has a solution and, if it does, whether the solution is unique. The main purpose of this paper is to revisit the uniqueness question of Problem 1, exhibit sufficient conditions for which the problem has a unique solution, and construct examples for which these conditions are satisfied. Those 10=idiv =in0,=0on[0, ]d=0forall [0,]=()0in (0,)=0on[0, ],0 =inuaSp TuQ TuTpxt TSfSu kSSQSTtSkS TSxS x n0, (1)",
null,
"K. B. FADIMBA542 0120C 2,gbgaCHbHaba (10) for all 01ab . Proof. We use a calculus argument. If , then the only value that =1ax can assume is 1, and (10) is obvious. For 00CThus, the combination of Lemma 2.1 and Lemma 2.2 gives an alternative way of proving that (6) holds, which in turns leads to uniqueness for Problem 1. Proof. We follow the lines of the proof of Proposition 3.2 of , with some modification. For the proof, it suf- fices to bound the quantity ,fxfx fakxx aKxKa independently of and ax. Thanks to the symmetry implied by (3), we prove this for 10ax1 only, without lost of generality; the rest of the prove can be obtained by the change of vari- able xx , for 21ax1x, and by using the fact that for 2kx c2 . Using (7) and (3), we obtain 1111=d.1xxaadKxKa ksscsscxa (14) Therefore, since ,0xakx, andKis increa- sing, 11111111fxfxfafxfx fakxxaKx KaKx Kafxfx facxafx fafx xacxaxa (15) By the Mean-Value Theorem, there exist such that <, 2axd. Hence >2cd (16) and >.2xd (17) Going back to (1 5 ) , w e get 11221122121||||12,Lfxfcfxfx fakxx aKxKacdfx fccddfx fcxccxcCf (18) where we have used (16), (17), and the fact that 0=0f. Therefore the lemma is proved. 3. Uniqueness of a Solution and Convergence of the Regularized Problem 3.1. Uniqueness We give an existence and uniqueness result for the case when and satisfy (9), i.e. ak asas acCksscKs Kc (19) for all , and for all 0cxc. We also give a conver- gence result for a perturbation of Problem 1 to a nonde- generate case in the next subsection. Under condition (19) and the analogue for the fract- ional flow function f, its is easy to see, through the proof of Theorem 6.1 of , that the following holds. Theorem 3.1 Suppose the data , af, and are Lip- schitz continuous in their argument ks. Then Problem 1 has a solution ,pS , with *210, ,,0,1 ..0,SLTHandtSxtae T . (20) Furthermore, if the pairs ,fk and satisfy (9), respectively, and if we assume that ,ak. ,,aSpL L , then the solution is unique. Copyright © 2011 SciRes. AM",
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"K. B. FADIMBA 544 3.2. Convergence of the Regularized Problem To get around the difficulties from the degeneracies of the problem, we perturb the diffusion coefficient, , to kk in such that a way that kkstrongly as 0. Define 0=sKs kd. (21) Then under the condition (19), the family of solutions ,pS converges to the unique solution ,pS of (1). More precisely. Theorem 3.2 Under the conditions of Theorem 3.1, let be the s olutio n to (1). For ,pS>0 small, say 10< <2, let ,pSk be the solution of (1) when is replaced by k, with k as described above. Then 2222 0, ,0, ,()()( )(),LTLLTLaSp pCaSaS (22) and 21*0, ,()00,1,() ()LTHTLSSKSKSS SCK K d (23) where 2=, with K and K 0defined by (7) and (21), respectively, and for some >. 4. Examples of Uniqueness In this Section, we describe the physical meanings of the parameters in Problem 1 and give an example that satis- fies conditions (2) through (3). These are purely mathe- matical examples that might not correspond exactly to models derived through physical experiments. Neverthe- less, the shapes of the graphs of the mobilities, the fract- ional flow function , and the conductivity, as functions of the saturation , resemble the ones obtained through experiments. See Figures 1-3, for S=32. For more details on the physical meanings of these parameters, see [1,2,10-12], for instance. We retain the simplicity of the examples below for the mathematical analysis in this paper. For these examples, the diffusion coefficient (also called the total mobility) of the pre- ssure equation of (1), as well as the fractional flow funct- ion, af, satisfy (5). Physically 12=asksks (24) where 1 is the mobility of the wetting phase, and the 2 the mobility of the nonwetting phase. The con- ductivity of the porous medium is defined by kk 1212d=dcksks pks ks kss, (25) where is the capillary pressure. Assuming cpddcps is bounded and bound ed away from 0, we will def ine, for this analysis, 1212=ksksks ks ks, (26) dropping, in this manner, the factor dpds. The fract- ional flow func tio n is defined by 112=ksfs ks ks (27) Figure 1. Fractional Flow. Figure 2. Mobilities. Copyright © 2011 SciRes. AM",
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"K. B. FADIMBA545 Figure 3. Conductivity of the Medium. and , the total mobility, is given by (24). aFor numerical modeling of immiscible two-ph ase flow through porous media, it has been used the following mobilities (see , for exam ple). 1=ks s (28) for the wetting, and 2=1ks s (29) for the nonwetting phase, up to multiplicative constants (or bounded functions). For a mathematical analysis purpose, and in order to get an example of uniqueness of a solution of Problem 1, we multiply both (28) and (29) by a bounded function of on the interval s0,1 . 4.1. A case of Uniqueness We define our new mobilities (up to the same multipli- cative constant) by the following. For 1< 2, let 21=e ,ssks s (30) for the wetting phase, and 22=1 e ,ssks s (31) for the non wetting phase. Then, the total mobility (up to a multiplicative constant K, the absolute permeabi- lity, which we take here to be 1) is given by 2=1essas ss , (32) while the conductivity of the medium (up to the same multiplicative constant K) is given by 21e=,1ssssks ss (33) and the fractional flow function is given by =1sfs .ss (34) It is clearly seen that , defined by (26), satisfies (2) and (3), and that kf and satisfy (5) for 1xy,Rx 0,1yR. Notice that the common denominator of both functions is positive in the interior of the region . See Figure 12 below. Functions F and Gare very complex by their defi- nition, especially for non integer values of . They in- volve the integral-defined function K. They e diffi- cult to handle algebraically. For the present work, we sketch the surfaces representing the two functions, above the region R, for some valu of ares, using Maple So- ware, in order to analyze their boundedness. This is illu- strated through the Figures 13 through 18. We notice ftthe smoothness of the surfaces correspond- ing to the case =2. This suggests that the two funct- ions are definitended in this case. For =2ly bou, we show directly that this is indeed the casethat Corollary 4.1 holds. W e prove this through the following lemma. Lemm, i.e. a 4.2 For =2, functions F and , defined by tiv G (38) and (39), resely, are bounded indepen- dently of pec,xy over the region R. Proof of Lemma From (32) and (34), i 4.2.t is easily seen that 1121=1xxfxxx (40) and 222=112123xxxxxxxx e .(41) s axCopyright © 2011 SciRes. AM",
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"K. B. FADIMBA 548 Figure 12. Region R. Figure 13. Surface=,zFxy, over region R, for =32. Figure 14. Surface=,zGxy x Figure 15. Surface=,zFxy, over region R, for=43. =,zGxyover region R, for =32. Figure 16. Surface, over region R, for=43. =,zFxy=2. Figure 17. Surface, over region R, for Copyright © 2011 SciRes. AM",
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"K. B. FADIMBA549 Figure 18. Surface =,zGxy, over region R, for =2. On the other hand, by the Mean-Value Theorem, we have 12,= =fxf xyfxfFxykxx ykx ykxk12 (42) and 34,= =axax yaxaGxy kxx ykx ykxk34 (43) where i, 14i , are between x and and wh ere we haveobtain from an) that y,d (43 used (7). We (42) 122fxfyk,Fx xk (4 an 4)d 34,2axaGxy kxk (45 Combining (33),(40 ), (41), (44), and (45), we obta)in 1122,= 1Fxy Oxx (4)and 6 1122=1 ,Ox (47) ,Gxy x as , . Hence, if yx"
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https://link.springer.com/article/10.1007/s11063-021-10564-0?error=cookies_not_supported&code=78c770e3-07b6-41a5-8c49-620c9dbbd52b | [
"## 1 Introduction\n\nThe outbreak of the (COVID-19) pandemic on the global scale led to the significant change in the world over the past year, destabilizing the global economy and stock markets. The massive economic hit from COVID-19 has dramatically increased financial risk and forced an increasing number of companies into bankruptcy. Financial risks, such as credit risk, operational risk, and business risk are generally uncertainties with any form of financing, which causes the difficulty of data analysis. Data analysis can help predict risk in advance, which is a key step for company decision-making [1, 2] in order to minimize the defaults. The evolving nature of the COVID-19 pandemic and the associated economic uncertainties require more efforts to support financial resilience. Therefore, the research on risk prediction is particularly important.\n\nMany methods have been proposed for financial data analysis, which can be generally divided into two categories: unsupervised approaches and fully-supervised approaches. Typical unsupervised methods include the popular clustering algorithms, such as the k-means algorithm , expectation–maximization (EM) algorithm and graph-partitioning algorithm . In , Kohonen’s self-organizing feature map is utilized to uncover automobile bodily injury claims fraud. In , a fuzzy clustering system is developed to detect anomalous behaviors in healthcare provider claims. In , unsupervised neural networks are utilized to identify fraud in mobile communications. In , hierarchical clustering method is developed to predict risks in insurance industry. These methods can automatically analyze the data without any prior information. However, they are generally limited to the accuracy of data analysis. Since no label prior is provided, they also cannot assign the clusters to the corresponding labels (lack of semantic understanding). Therefore, it’s hard to evaluate the performance of these unsupervised clustering methods. As suggested in , a multiple criteria decision making strategy can better evaluate clustering algorithms in the domain of risk analysis. Typical fully-supervised methods include the machine learning-based methods [11, 12]. Compared with unsupervised methods, fully-supervised methods can generally achieve higher prediction accuracy. However, the high-quality performance of fully-supervised methods relies on large amount of training data. They are inapplicable when not enough labeled data is provided. Due to uncertainty in financial data, these fully-supervised approaches generally lack versatility. For example, a trained model for credit risk analysis cannot be applied for business risk analysis. They need to retrain the model with the new labeled data in business risk.\n\nTo address the above problems, in this paper, the semi-supervised scheme is explored for financial data analysis. Only a small amount of labeled data is needed in semi-supervised scheme. Then all the unlabeled data can be automatically clustered based on the labeled data. Compared with unsupervised methods, the label (normal or abnormal) of each data can be specifically determined in semi-supervised strategy since each label prior is provided. Furthermore, the provided label information can help to improve the clustering performance. Compared with fully-supervised methods, semi-supervised scheme has greater versatility and it can be directly applied to different data without any additional cost. Moreover, only a small amount of labeled data is needed to obtain a semantic classification. Comprehensively, semi-supervised scheme is more practical for financial data analysis.\n\nIn the semi-supervised model [13,14,15], the label information can be propagated from labeled data to unlabeled data based on their pairwise relationships. The data manifold is represented as a weighted graph, where the vertices in the graph represent each data and the edge connecting two adjacent vertices is determined by the initial pairwise similarity values. After the diffusion, the geometry of the data manifold can be effectively captured. However, due to lack of sufficient distinguishability, the conventional semi-supervised approach cannot obtain accurate risk prediction with limited labeled data, and also be sensitive to the number of labeled data. Furthermore, the pairwise similarity is not always consistent with the category information, which causes the label prior cannot be correctly propagated following the mismatched smoothing structure.\n\nThe contributions of this paper can be described as: first, instead of directly propagating the’hard’ prior label information, we transform the’hard’ prior information to the’soft’ global probability first, and then the’soft’ prior probability is propagated to learn the posterior probability, which helps to produce more accurate risk prediction and specific semantic labeling without the demand of a large number of labeled data; second, the label prior is utilized to correct the pairwise relationship, trying to make the structures of data affinity and labeling more consistent, and an automatic fusion strategy is proposed to effectively combine the data affinity and the labeling information by an adaptive label diffusion framework.\n\n## 2 Conventional Semi-supervised Model\n\nA set of financial data can be denoted as $$X = \\left\\{ {x_{i} } \\right\\}_{{i = 1}}^{N}$$, where $$x_{i} \\in \\mathbb{R}^{d}$$ represents the risk factors of each data, $$d$$ is the number of attributes, and $$N$$ represents the number of data. The purpose of data clustering is to assign each data $$x_{i} \\in X$$ a risk discriminating label $$f_{i} \\in L$$, where the label set $$L$$ generally contains two label values, one is normal (no risk) and the other is abnormal (risky). In semi-supervised scheme, a small amount of data is labeled for each label first. The labeled data set with each label $$l \\in L$$ is denoted as $$X^{l} \\subset X$$. The label information is then propagated from the labeled data to unlabeled data following the structure of their pairwise similarities $$W = [W_{{ij}} ]_{{N \\times N}}$$, generally defined as a typical Gaussian function:\n\n$$W_{{ij}} = \\exp \\left( { - \\nu \\left\\| {x_{i} - x_{j} } \\right\\|_{{\\text{2}}}^{{\\text{2}}} } \\right)$$\n(1)\n$$\\nu = \\frac{1}{{2{\\text{EP}}\\left( {\\left\\| {x_{i} - x_{j} } \\right\\|_{2}^{2} } \\right)}}$$\n(2)\n\nwhere $$i$$ and $$j$$ represent the data $$x_{i}$$ and $$x_{j}$$, respectively. The automatic constant $$\\nu$$ is utilized to control the strength of the weight and $$\\text{EP} ( \\cdot )$$ represents the expectation over all data pairs. It can be noticed that the weight $$W_{{ij}}$$ is large (close to 1) if their attribute characteristics are similar, and vice versa.\n\nAs described in , the label learning process with respect to the label $$l \\in L$$ can be formulated as minimizing:\n\n$$E(\\Pi _{l} ) = \\sum\\limits_{{i,j = 1}}^{N} {W_{{ij}} (\\pi _{{il}} - \\pi _{{jl}} )^{2} } + \\lambda \\sum\\limits_{{i = 1}}^{N} {d_{i} } (\\pi _{{il}} - z_{{il}} )^{2}$$\n(3)\n\nwhere $$\\Pi _{l} = [\\pi _{{il}} ]_{{N \\times 1}}$$ represents the posterior probability of being learned with the label $$l$$. $$d_{i} = \\sum\\nolimits_{{j = 1}}^{N} {W_{{ij}} }$$ and $$\\lambda = (1 - \\alpha )/\\alpha$$ $$(0 < \\alpha < 1)$$ is utilized to balance these two energy terms. $$z_{{il}}$$ represents the’hard’ prior label information, where $$z_{{il}}$$ equals 1 if $$x_{i}$$ is labeled with $$l$$, and otherwise equals 0.\n\nThe first energy term in Eq. (3) restricts that if the pairwise similarity $$W_{{ij}}$$ is large, $$x_{i}$$ and $$x_{j}$$ should have similar posterior probabilities. The second energy term in Eq. (3) tries to keep the posterior probability be consistent with the’hard’ prior condition.\n\nAfter derivation optimization, it has:\n\n$$\\Pi _{l} = (1 - \\alpha )(I - \\alpha P)^{{ - 1}} Z_{l}$$\n(4)\n\nwhere $$P = D^{{ - 1}} W$$ with $$D = diag([d_{1} ,...,d_{N} ])$$, $$I$$ is an identity matrix, and $$Z_{l} = [z_{{il}} ]_{{N \\times 1}}$$. Suggested by , the above probability learning process is also equivalent to the following label diffusion strategy:\n\n$$\\Pi _{l} ^{{(t + 1)}} = \\alpha P\\Pi _{l} ^{{(t)}} + (1 - \\alpha )Z_{l}$$\n(5)\n\nwhere $$t$$ represents the diffusion steps. $$\\Pi _{l} ^{{(t + 1)}}$$ converges to the same solution with Eq. (4) when $$t \\to \\infty$$. The final labeling can be obtained as:\n\n$$f = \\arg \\mathop {\\max }\\limits_{l} \\Pi _{l}$$\n(6)\n\n## 3 The Proposed Model\n\nThe above ‘hard’ label diffusion model is not suitable for data analysis since the limited label information cannot be correctly propagated following the inaccurate structure of data affinity. We estimate the ‘soft’ prior probability from the ‘hard’ labeled data first, which can also be regarded as a unary diffusion process from the local seeds to the global probabilities. The prior probability that $$x_{i}$$ belongs to the label $$l$$ can be estimated as:\n\n$$\\bar{\\pi }_{{il}} = \\exp \\left( { - \\left\\| {x_{i} - c_{l} } \\right\\|_{2} } \\right)$$\n(7)\n\nwhere $$c_{l}$$ represents the clustering center produced by unsupervised clustering algorithms, such as the k-means algorithm , from the labeled data set $$X^{l}$$. The value is normalized under the constraint $$\\sum\\nolimits_{{l \\in L}} {\\bar{\\pi }_{{il}} } = 1$$. If $$x_{i}$$ is close to the clustering center, its prior probability $$\\bar{\\pi }_{{il}}$$ is large, and vice versa.\n\nIn order to keep the labeling and data affinity consistent, we should try to merge these two kinds of information before the label diffusion. For easy combination, we represent them in the same dimensional space:\n\n$$W^{{(1)}} = W$$\n(8)\n$$W^{{(2)}} = \\sum\\limits_{{l \\in L}} {\\bar{\\Pi }_{l} \\bar{\\Pi }_{l} ^{\\text{T} } }$$\n(9)\n\nwhere $$\\bar{\\Pi }_{l} = [\\bar{\\pi }_{{il}} ]_{{N \\times 1}}$$. $$W^{{(1)}}$$ represents data similarity in the feature space and $$W^{{(2)}} \\in \\mathbb{R}^{{N \\times N}}$$ is a similarity matrix in the label space.\n\nBorrowing ideas from the binary affinity fusion model in image retrieval , the automatic fusion strategy for data analysis is described as:\n\n$$E(\\Pi _{l} ,\\beta ) = \\sum\\limits_{{h = 1}}^{H} {\\beta _{h} \\left[ {\\sum\\limits_{{i,j = 1}}^{N} {W_{{ij}}^{{(h)}} \\left( {\\pi _{{il}} - \\pi _{{jl}} } \\right)^{2} } + \\lambda \\sum\\limits_{{i = 1}}^{N} {d_{i}^{{(h)}} \\left( {\\pi _{{il}} - \\bar{\\pi }_{{il}} } \\right)} ^{2} } \\right]} + \\frac{1}{2}\\gamma \\left\\| \\beta \\right\\|_{2}^{2} ,s.t\\sum\\limits_{{h = 1}}^{H} {\\beta _{h} } = 1$$\n(10)\n\nwhere $$H$$ is the number of fusion components ($$H = 2$$), $$d_{i}^{{(h)}} = \\sum\\nolimits_{{j = 1}}^{\\text{N} } {W_{{ij}}^{{(h)}} }$$, $$\\beta = [\\beta _{h} ]_{{H \\times 1}}$$ ($$0 \\le \\beta _{h} \\le 1$$), and $$\\gamma$$ is an adjusting parameter to control the influence of the last energy term. The fusion coefficients $$\\beta _{1}$$ and $$\\beta _{2}$$ can be automatically learned. Compared with the affinity fusion with diffusion model , the proposed model focuses on automatically determining the fusion coefficient for the information at the feature space and the label space, respectively, by a unary label diffusion framework.\n\nEquation (10) can be reformulated as the matrix form:\n\n$$E\\left( {\\Pi _{l} ,\\beta } \\right) = \\sum\\limits_{{h = 1}}^{H} {\\beta _{h} \\left[ {\\Pi _{l}^{{\\text{T}}} L^{{(h)}} \\Pi _{l} + \\lambda \\left( {\\Pi _{l} - \\bar{\\Pi }_{l} } \\right)^{{\\text{T}}} D^{{(h)}} \\left( {\\Pi _{l} - \\bar{\\Pi }_{l} } \\right)} \\right]} + \\frac{1}{2}\\gamma \\left\\| \\beta \\right\\|_{2}^{2}$$\n(11)\n\nwhere $$L^{{(h)}} = D^{{(h)}} - W^{{(h)}}$$ is the Laplacian matrix with $$D^{{(h)}} = diag([d_{1}^{{(h)}} ,...,d_{N}^{{(h)}} ])$$.\n\nTwo variables are contained in Eq. (11) and their values are updated iteratively. Differentiating $$E(\\Pi _{l} ,\\beta )$$ with respect to $$\\Pi _{l}$$ first, it has:\n\n$$\\Pi _{l} = (1 - \\alpha )\\left( {\\sum\\limits_{{h = 1}}^{H} {\\beta _{h} D^{{(h)}} } - \\alpha \\sum\\limits_{{h = 1}}^{H} {\\beta _{h} W^{{(h)}} } } \\right)^{{ - 1}} \\sum\\limits_{{h = 1}}^{H} {\\beta _{h} D^{{(h)}} } \\bar{\\Pi }_{l}$$\n(12)\n\nSubstituting Lagrange term into Eq. (11) and differentiating $$E(\\Pi _{l} ,\\beta )$$ with respect to $$\\beta _{h}$$, it has:\n\n$$\\beta _{h} = \\frac{1}{H} + \\frac{{\\sum\\limits_{{h = 1}}^{H} {M_{h} } }}{{H\\gamma }} - \\frac{{M_{h} }}{\\gamma }$$\n(13)\n\nwhere $$M_{h} = \\Pi _{l} ^{\\text{T} } \\text{L} ^{{(h)}} \\Pi _{l} + \\lambda (\\Pi _{l} - \\bar{\\Pi }_{l} )^{\\text{T} } D^{{(h)}} (\\Pi _{l} - \\bar{\\Pi }_{l} )$$. Based on the constraint $$0 \\le \\beta _{h} \\le 1$$, we can derive $$\\gamma \\ge {\\text{|}}M_{1} - M_{2} {\\text{|}}$$. Consequently, the detailed steps of the proposed algorithm are described as:\n\n 1. Initializing the parameters: $$\\alpha$$ and $$\\gamma$$ 2. Setting the initial $$\\beta _{h} = 1/H$$ and $$f^{{old}} = [ - 1]_{{N \\times 1}}$$ 3. Estimating prior probability $$\\bar{\\Pi }_{l}$$ with Eq. (7) 4. Computing $$W^{{(1)}}$$ and $$W^{{(2)}}$$ with Eqs. (8–9) 5. Estimating posterior probability $$\\Pi _{l}$$ with Eq. (12) 6. Updating the value of $$\\beta$$ with Eq. (13) 7. Computing the new labeling $$f^{{new}}$$ with Eq. (6) 8. Checking the termination condition: if $$f^{{new}}$$ equals $$f^{{old}}$$, stop; otherwise $$f^{{old}} = f^{{new}}$$, go to 5\n\n## 4 Experiments\n\nTo evaluate the performance of the proposed semi-supervised clustering algorithm for financial risk prediction, two public credit approval risk data sets: German and Australian credit card application data sets, and one public Chinese growth enterprise market (GEM) dataset, are selected in this paper. There are common uncertainties with different forms of financing in these three datasets and the potential financial risks lead to the necessary risk prediction in order to minimize the defaults in advance. Therefore, the above datasets are suitable for our experiments. The compared clustering approaches include the popular k-means (KM) algorithm , the expectation–maximization (EM) algorithm , the repeated-bisection (RB) algorithm , the graph-partitioning (GP) algorithm , the density-based (DB) algorithm , the conventional semi-supervised learning (SSL) algorithm and the state-of-the-art tensor product graph-based (TPG) algorithm .\n\nIt is hard to judge the performance of the algorithm with a single evaluation index. In this paper, four quantitative indexes: Precision, Purity , True Positive Rate (TPR) and True Negative Rate (TNR) are utilized to evaluate the compared methods. Precision represents the percentage of a cluster that contains positive objects, where in risk analysis, a positive class normally refers to bankrupt, fraudulent or erroneous activities. Purity is a simple measure of the number of correctly assigned objects in clustering. TPR measures in all positive instances how many instances are predicted to be positive category (correct prediction rate for positive instances), and TNR measures in all negative instances how many instances are predicted to be negative category (correct prediction rate for negative instances). Negative class is normal activities in risk analysis. More detailed definition of the above indexes can refer to this paper . For the four evaluation indexes, a larger value represents a better clustering result.\n\nTwo controlling parameters $$\\alpha$$ and $$\\gamma$$ are involved in the proposed algorithm and we set them to 0.3 and 10,000, respectively. For the semi-supervised algorithms SSL and the proposed method, 10% data is randomly selected as the labeled samples each time. We repeat the experiment 20 times and select the average performance as the final result.\n\nThe German credit card application data set was provided by UCI machine learning databases , which contain 1000 instances with 24 dimensional features and 1 label variable. The features correspond to the status of existing checking account, duration, credit history, purpose of credit application, credit amount, education level, employment status, personal status, other debtors, present residence, property type, age, job, and so on. The label variable describes whether an instance is accepted or declined, in which 70% instances are accepted and 30% instances are declined. Table 1 lists the Precision, Purity, TPR and TNR values of all compared methods in this data set, where the results of KM, EM, RB, GP and DB are reported in . It can be seen that KM, EM, RB and DB obtain low precision values (below 0.3). Though GP obtains a high precision value 0.61, the TPR and TNR values are low. The proposed method obtains the highest precision, purity and TNR values among all the compared methods. Furthermore, compared with semi-supervised methods SSL and TPG, the proposed method obtains better performance in precision, purity, TPR and TNR, which validates the effectiveness of the proposed model in this data set.\n\nThe Australian credit card application data set was provided by a large bank and concerns consumer credit card applications , which contains 690 instances with 14 dimensional features and 1 label variable. To protect confidentiality of the data, attribute names and values have been changes to meaningless symbols. Attribute types include continuous, nominal with small number of values, and nominal with larger numbers of values .The label variable describes whether an instance is accepted or declined, in which 55.5% instances are accepted and 44.5% instances are declined. Table 2 lists the Precision, Purity, TPR and TNR values of all compared methods in this data set, where the results of KM, EM, RB, GP and DB are reported in . It can be seen that RB obtains the highest precision and TNR values 0.92 and 0.92. By comparison, the proposed method obtains slightly lower precision and TNR values 0.88 and 0.91 than RB. However, the proposed method produces much higher purity and TPR values than RB. Compared with semi-supervised methods SSL and TPG, the proposed method obtains higher values in precision, purity, TPR and TNR, which validates the effectiveness of the proposed model in this data set. By comprehensive comparison with all the methods, our method obtains the best performance in Australian credit card application data set.\n\nTo specially verify the effectiveness among the semi-supervised approaches, we further chosen the Chinese GEM dataset provided by the Wind databaseFootnote 1 to conduct the comparison, from which we selected 360 companies from 2016 to 2018 with 24 dimensional features. The features correspond to the status of existing return on equity, return on total assets, net profit margin, gross profit margin, earnings per share, current ratio, quick ratio, equity ratio, receivables turnover ratio, current assets turnover, total assets turnover, working capital turnover rate, sales to cash ratio, operation safety rate, intangible assets ratio, and so on. Meeting one of the following conditions: 1) net assets are negative, 2) the net profit is negative and the net interest rate of the previous year is less than 10%, 3) the opinion category of audit report is qualified opinion or unable to express opinion, then an instance was identified as at risk. As a result, 75% instances are accepted and 25% instances are declined in this dataset. Table 3 lists the Precision, TPR and TNR values of the semi-supervised approaches SSL, TPG and the proposed method on the data from 2016 to 2018. Though SSL obtains the highest TNR values, its TPR values are very low, which implies many risky instances are wrongly classified into the risk-free category. It's obvious the proposed method produces the superior performance with the highest Precision and TPR values.\n\nThe similarity matrices $$W^{{(1)}}$$ (at the feature space) and $$W^{{({\\text{2}})}}$$ (at the label space) are automatically merged by a label diffusion framework in this paper. To test the effectiveness of the proposed fusion strategy, Tables 4, 5 list the comparison results with and w/o fusion in German credit card application data set and Australian credit card application data set, respectively. From the quantitative comparisons in these two data sets, we can find that the proposed method with fusion produces higher Precision, Purity and TNR values than the approach without fusion.\n\nThe number of labeled data can affect the performance of the semi-supervised algorithms. Figure 1 shows the performance of the proposed algorithm with different percentage of labeled data in Australian credit card application data set. It can be seen that the values of Precision, Purity, TPR and TNR become higher along with the increase of the percentage of the labeled data. It can be also noticed that the values of Precision, Purity, TPR and TNR are around 0.8 with only 1% labeled data, which is still better than the most compared methods.\n\nThere are two controlling parameters $$\\alpha$$ and $$\\gamma$$ involved in the proposed model. Parameter $$\\alpha$$ is utilized to control the extent of label diffusion in Eq. (12). Figure 2 shows the performance curves with different values of $$\\alpha$$ in German (left) and Australian (right) credit card application data sets. A too large value of $$\\alpha$$ will lead to an over-smooth result that apart from the labeled data, the rest positive instances are easily misclassified as negative category. Therefore, from the curves, we can find that the values of Precision and TNR become higher and the values of Purity and TPR become lower when $$\\alpha$$ increases. Parameter $$\\gamma$$ is utilized to control the fusion process in Eq. (13). As described before, the value of $$\\gamma$$ should be larger than $${\\text{|}}M_{1} - M_{2} {\\text{|}}$$ in each iteration in order to satisfy the constraint $$0 \\le \\beta _{h} \\le 1$$. Therefore, we should assign a large but not too large value to parameter $$\\gamma$$ since a too large $$\\gamma$$ will impose an average fusion constraint. Figure 3 shows the performance curves when $$\\gamma$$ varies from 8000 to 25,000 in German (left) and Australian (right) credit card application data sets. It can be seen that in this interval values, the performance is not sensitive to the change of $$\\gamma$$. In this paper, the value of $$\\gamma$$ can be loosely set to 10,000.\nTable 6 lists the algorithm complexity and the average running times of the semi-supervised approaches SSL, TPG and the proposed method on an Intel Core i7-7700 K CPU with 16 GB memory running at 4.20 GHz in MATLAB R2017a. The algorithm complexity of SSL and the proposed method are both $$\\mathcal{O}\\left({N}^{2}\\right)$$, which mainly focuses on the inversion operation of a similarity matrix. In the algorithm implementation, the multiplication of the inversion matrix by a single vector can be efficiently solved by the MATLAB division operator ‘\\’. The algorithm complexity of TPG is $$\\mathcal{O}\\left({N}^{2.4}\\right)$$ using the Coppersmith-Winograd algorithm, which mainly focuses on the iterative matrix product operation for a higher-order tensor product graph optimization. Limited by the iterative optimization for $$\\Pi$$ and $$\\beta$$, the average running time of the proposed method is 0.9 s which is slightly higher than SSL and TPG."
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