# All Questions

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### Is it possible to save an interrupted computation?

I've got this really time consuming factoring problem. To decouple things a bit, I decided to start Mathematica using the command line interface (under screen). ...
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$Assumptions = x ∈ Reals && y ∈ Reals && a ∈ Reals && b ∈ Reals; These work: ... 1answer 65 views ### How can I substitute something using only map? For example, I have the equation x^2 + y^2 == x*y and I want to apply the rule y -> s*x I can do it easily by ... 0answers 34 views ### Generating partitions of a set with a specified size of the parts [duplicate] I tried the following (inspired by the answer here) myList = {a, b, c}; Needs["Combinatorica`"]; SetPartitions[myList] and I got this answer, ... 1answer 51 views ### Preventing cell height adjustment when rotating 3D graphics I have a large dataset of scattered x,y,z coordinates. I am trying to use ListPointPlot3D to identify outliers in 3D. This involves generating a plot and then ... 0answers 16 views ### Rationalizing Denominators with Radicals [migrated] How do you rationalize this fraction: 1/(sqrt(n+1)) 0answers 55 views ### Bounds on random number I have a Markov Chain Monte Carlo code that uses a chi squared function to fit some data. I am running into an issue now with getting unrealistic values for some of the free parameters in the code. ... 2answers 82 views ### Visualize Plot of a function of 3 Variables using color and contours I would like to plot a function of three variables, say for example: $$f(x,y,z) = x^2+y^3+z^4$$ over$[-1, +1]$. I want my plot to use colors and maybe contours to make this visualization possible ... 0answers 67 views ### Using NDSolve for Integro-Differential Equations I have a fairly complicated set of coupled non-linear integro-differential equations that I am trying to solve using NDSolve. The equations are: ... 1answer 53 views ### Creating a NearestFunction that returns an index I use Nearest repeatedly for large data sets. For example pts = RandomReal[{-1, 1}, {1000, 3}]; Nearest[pts, {0, 0, 0}] I ... 0answers 79 views ### Performance in parameter estimation from ParametricNDSolve using varied initial conditions I have 250 data points from a timecourse exeriment in a list, with columns specifying (1) time, (2-4) initial conditions, (5) absorbance reading. I want to fit 4 parameters (k1, k2, k3, k4) in a DAE ... 2answers 43 views ### Expanding Matrix Expressions I want Mathematica to recognize that A.(-B.C)+A.B.C = 0 Yet FullSimplify and the like leaves the expression as it is. How do I get around this? 4answers 147 views ### Unexpected behavior of Unevaluated Maybe it is about time I read some proper text about the main loop. Maybe I should not care (so much) about Unevaluated (as Leonid suggests). But I think this is an interesting question anyway. This ... 1answer 74 views ### Mathematica output in ASCII or larger text size for the output? I am trying to read the output of this code that has crosses, circles and spaces. For some reason, the output is in very-very small alphabets so I would like to get it in ASCII and/or in larger ... 0answers 61 views ### Generate a list without braces? [closed] Ultimately I want to plot a user-created function for many input parameters. Plot[{P[1,k], P[2,k], P[3,k], P[4,k], P[5,k]}, {k, 0, 500}] but I need to generalize ... 2answers 106 views ### Why is this parallel evaluation with Dispatch[] so slow? Can you efficiently parallelize this? The parallel versions are much slower than the sequential version, and I'm not sure why. Does SetSharedVariable allow ... 1answer 55 views ### How to enumerate multisets Given the eight-element set {1,2,3,4,5,6,7,8}, I would like to enumerate all multisets (subsets with repetition) of size n, where n >=3. For example, with n = 3, the sets {1,1,1}, {1,1,2}, ..., ... 1answer 57 views ### NDSolve with vector function (Possible duplicate yet I still can't understand.) Basic 2D revolving around origin: ... 3answers 134 views ### Using ImageTransformation[] with a lookup table I need to transform images by ImageTransformation in a time critical application. Therefore I precalculate a lookup table lut of ... 0answers 33 views ### How can I assigne EdgeCost for the graph edges? [duplicate] Here is my ... 1answer 66 views ### How to crop graphics outside PlotRange with Show? [duplicate] Is there an option or method to prevent Graphics from being displayed outside the PlotRange region? The problem is illustrated ... 0answers 35 views ### A Symbol with Subscript and Superscript as an Axis Label I am trying to have the symbol$\epsilon_{9/2,4}^-$as the axis label in a graph in Mathematica. First problem is that: when I use Subscript[$\epsilon$,9/2,4], 9/2 changes to$\frac{9}{2}$(which I ... 2answers 58 views ### Plotting points and functions in one graphic I have this plot: Plot[{0 x, -x, x, -Sqrt[2 - x^2], Sqrt[2 - x^2]}, {x, -3, 3}, PlotStyle -> {Purple}] Now I want to do the following. I want to plot the ... 1answer 82 views ### TextRecognize with crosses, circles and spaces results into oddities, why? I am investigating this answer here about detecting crosses and circles with TextRecognize. I tried to solve this problem here by directly using the builtin command TextRecognize but it does not work ... 0answers 52 views ### Problems with ListDensityPlot I have the errors in one quantity$x$in a List form as$(\Delta x,z)$, being$\Delta x$the error and$z$the value in which$x$has the respective error. I want to make a density plot of the errors ... 0answers 39 views ### CDF Player: MathKernel.exe uses a lot of memory When I run this CDF document http://x6174x.blogspot.pt/2013/04/bankroll-growth-simulator.html on my desktop, each time I press "Run again" the Task Manager shows that the MathKernel.exe process ... 2answers 101 views ### How to simplify an expression with special functions to zero The following is a well-known Bessel function identity: $$J_{-n}(z)=(-1)^n J_n(z),\qquad n\in\mathbb Z$$ To check this, I used the following code and the result is as what I expected. ... 0answers 26 views ### Behavior of$PreRead in Kernel

I am interested in making a simple accounting style line calculator that allows me to interact with it something like this: ...
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### How can I use mathematica to price Amazon's S3?

Amazon provides a html form for its price model of cost per gB usage. I'm trying to figure out the formula behind it, is there a way to use Mathematica to generate data from the form and then ...
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### How to select elements from a 4D Array?

I am very new to Mathematica (first time!) and I'm already having troubles with arrays. I basically have a 4D tensor, that is a matrix (call it M) which has for ...
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### Normalize the PlotLegends and z values for two DensityPlot

I'm trying to compare two DensityPlots: ...
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### permutation and abstarct-algebraShow that there does not exist a permutation α in S4 satisfying (1 2)(3 4)α = α(1 2 3 4)? [migrated]

Show that there does not exist a permutation α in S4 satisfying (1 2)(3 4)α = α(1 2 3 4)?
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### List Plot 3D the same colour scale

I have a transient problem of pressure disipation. I want to plot severals 3D plot but I have a problem with colours. Case: One of my ListPlot3D presents pressure ...
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### Monitor the list for changes

I wrote a function to monitor the list of variable. What it does is if the variable in list change, the changed variable will be separated from others. check the function and output ...
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### The Orbit and Perigee of the Flamsteed comet

Historical context This year we have the 330-th anniversary of the Battle of Vienna - one of the great formative events of European history, it took place on September 12, 1683. Kara Mustafa, Grand ...
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### Integration of a rational function

I am trying to solve the following rational integral (I got assistance here): $$\int_{-\infty}^{\infty}{\frac{a+x}{b^2 + (a+x)^2}\frac{1}{1+c(a-x)^2}}dx$$ where $\{a, b, c\}\in \mathbb{R}$. I would ...
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### Evaluating the different calculations

I am a new user. I wonder that either there is possible to evalute different calculations at the same time in Mathematica or not? Can i share the kernels for different calculation at same time?
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### (x^2 + 5)^2 - 15(x^2 + 5) + 54 = 0 [migrated]

I got the square root of 14 and 11 but the answer book states that these answers are wrong. Can someone help me? I used this formula to find the individual roots x = - p/2 + or - √ (p/2)^2 - q
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### Solve √(2x-5) - √(x-1) = 1 [migrated]

Although this is a simple question I for the life of me can not figure out why one would get a 2 in front of the second square root when expanding. Can someone please explain that to me? Example: ...
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### Use Initialization Cells to open a CellGroup

I would like to use "Evaluate Initialization Cells" to open a CellGroup in a notebook. However, the following code doesn't work if placed in an initialization cell: ...
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### Reducing exponential inequalities fails

I am quite stumped by this problem : Reduce[ N^(x-y) <1 && N > 0 , x, Reals] gives the expected result ...
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### Solving for variables in a series of nonlinear equations [closed]

I have a nonlinear expression in five variables. I want to use Mathematica to solve for three of the variables. I have a series of points giving values of x an y and I am trying to solve for a,b, and ...
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### Generating partitions of a set [duplicate]

Is it possible to get Mathematica to generate all possible partitions of a set of objects? (..or equivalently if it can be made to do the cumulant expansion or at least the Gaussian special case of ...
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### Concerning ShowLegend in Mathematica

I found a code for Mie Scattering from 2007, written for Mathematica. I have edited it quite a bit, since there are package definitions that we don't need, etc. But I am having difficulties ...
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### Using Parallelize on a For loop

Say I have a For loops the following, ...
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### When using NMinimize[…,Method->“DifferentialEvolution”] is an “iteration” different than a “step”?

Hopefully this question has a simple answer. I have the following bit of code: ...
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### How do I operate on a set of ordered pairs? [closed]

I have a calculation that will give me a lot of ordered pairs. For each such pair in a list, I want to square the elements and add them together. Here is an example of the kind of list I have ...
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### Solving homogeneous Fredholm Equation of the second kind

I am trying to solve a homogeneous Fredholm integral equation of the second kind, i.e. $\lambda y(x) = \int\limits_a^b e^{i[\phi(t)+k(t-x/M)^2]} y(t)\,dt$ where $\lambda$ is the eigenvalue (to be ...
### White noise $\eta(t)$
How to make a random function $\eta(t)$ to insert in a differential equation for NDSolve? Edit: example: to solve equations like $\frac{dx}{dt}=\eta(t)$