# All Questions

263 views

### List of Tribonacci Polynomials with Mathematica? [duplicate]

I want to list top ten of Tribonacci polynomials. I have following algorithm, but it doesnt work. ...
181 views

### How to combine SparseArray and If

Because I am dealing with huge matrixes, my computer can not handle it, because of the memory. But, in my matrix, a very small percentage of the elements are non-zero. So I should use SparseArray as ...
246 views

### What is the underlying algorithm for GroupElementToWord?

What algorithm is Mathematica 9 using for GroupElementToWord[group, g]?
453 views

### Translating a “Point-to-Triangle” distance script from MATLAB to Mathematica

Update - Thanks everyone for your responses! After fixing a problem with vector normalization, the code below now works. I'm a new user, and I was attempting to port some Mathematica code from ...
174 views

### Is it possible to run Mathematica on an HPC cluster with Torque?

I'm installing Wolfram gridMathematica in HPC cluster with TORQUE Resource Manager. There is a big problem because Mathematica suppost PBS pro. Can you help me or give some advice or coments?
144 views

### Dynamic Updating CreateDialog Problem

In this code, one cannot close the dialog window: {TogglerBar[Dynamic[x], Range[5]], Dynamic[x], Dynamic[CreateDialog[x]]} If I use ...
212 views

### How to generate characters by a function which works like the Esc + a + ESC

How to generate characters by a function which works like the Esc + a + ESC ...
171 views

### Graphics3D: the box vertices do not coincide with triangle

I have drawn a triangle using Line graphics primitive and Graphics3D function: ...
343 views

### Write a function that returns the logarithmic derivative

How can we write a function that if we input an expression f, it returns the log derivative $\frac{1}{f} \frac{df}{dx}$. We have to use a conditional or pattern test so that the function accepts any ...
34 views

### How to tell Mathematica to use Real Only Mode [duplicate]

How do I tell Mathematica to use real only mode. For example if I want to graph $(x-1)^{1/3}$ for $-3<x<3$, I need to use Real Only mode to get the right graph.
160 views

### 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). ...
314 views

$Assumptions = x ∈ Reals && y ∈ Reals && a ∈ Reals && b ∈ Reals; These work: ... 1answer 137 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 39 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 187 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 ... 2answers 178 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 2k 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 606 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 162 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 283 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 237 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? 3answers 297 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 129 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 ... 3answers 323 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 ... 2answers 178 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, ... 1answer 357 views ### NDSolve with vector function (Possible duplicate yet I still can't understand.) Basic 2D revolving around origin: ... 3answers 284 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 46 views ### How can I assign EdgeCost for the graph edges? [duplicate] Here is my code: ... 1answer 231 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 ... 2answers 497 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 450 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 135 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 100 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 197 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 39 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: ...
175 views

### 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 ...
281 views

### Normalize the PlotLegends and z values for two DensityPlot

I'm trying to compare two DensityPlots: ...
162 views

### 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 ...
134 views

### 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 ...
1k views

### 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 ...
145 views

### 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 ...
71 views

### 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: ...
373 views

### Reducing exponential inequalities fails

I am quite stumped by this problem : Reduce[ N^(x-y) <1 && N > 0 , x, Reals] gives the expected result ...
318 views

### 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 ...
416 views

### 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: ...
240 views

### 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 ...
379 views

### 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 ...
148 views

In order to make my computations faster I have developed a C/C++ application calling Mathematica kernel and performing many operations using Mathematica functions for equation solving. Now I want to ...
### 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 $\frac{dx}{dt}=\eta(t)$