1
vote
0answers
333 views

Solving two-component two-dimensional differential Equation with NDSolve (Brusselator Model)

I'm trying to solve a two-component two-dimensional reaction-diffusion differential equation system with Mathematica. The background of the model is the so called "Brusselator Model" where one can ...
2
votes
0answers
68 views

RDPStruct.exe: what is it and why are there so many?

I have an old (v7) webMathematica system running and it seems to generate a lot of RDPStruct.exe processes. First, what does this "Converter" do? GIF.exe and JPEG.exe are obvious, but "RDPStruct" ...
2
votes
3answers
310 views

Alternative ways to AppendTo and Delete in a While loop

Is there an alternative way to do AppendTo and Delete and also replace k0 during every ...
0
votes
1answer
106 views

Tab between elements in a GUI layout

If I have a bunch of input fields, I can tab between them quite conveniently, but if I want to navigate between the input fields and another element (in my case, a button), I have to click on the ...
2
votes
0answers
19 views

In a Function, how to Ensure Code Runs Prior to an Abort [duplicate]

Is there a way to set aside some code in a function that will be triggered to run if the evaluation of the function is aborted by a user? Specifically, I have a function that has to open a log file to ...
2
votes
1answer
111 views

Table with some editable cells

I have a table: I want it to be editable only where the zeros appear. I read this post Generating an editable table that can be used as input because it's almost exactly what I want, but I couln't ...
0
votes
1answer
64 views

Inequality test returned unevaluated

I tried, Refine[Sin[k]^2/(k^2 + k + 1) < 1/(k^2), Element[k, Integers]] $\frac{\text{Sin}[k]^2}{1+k+k^2}<\frac{1}{k^2}$ It returns unevaluated. I ...
1
vote
0answers
67 views

How to find a scaling parameter in matrix inversion process by MMA?

I simply would like to find the inverse of a given matrix $A$ by the iterative method $X_{k+1}=X_k(2I-AX_k)$ using $X_0=\frac{1}{\sigma_{max}^2}A^*$. An example is as follows ...
3
votes
1answer
74 views

Convert an expression's symbols of form a$x to a[x]

I want a function that takes expressions of the following form: a$x and converts them to a[x]. In particular, consider the ...
1
vote
2answers
109 views

Clearing arguments passed to a Module

Is there a possible way to clear the arguments passed to a module to release some memory. I believe that arguments passed to modules are passed by value rather than pass by reference. e.g. I have the ...
1
vote
0answers
145 views

Code for solving numerically an integro-differential equation

First of all, I want to greet the community. This is my first question, but I hope I will be able to help answering others members questions, although I am quite new working with Mathematica. I would ...
2
votes
2answers
148 views

Create a Figure with a sequence of Balanced Binary Trees

I would like make the attached image by Mathematica. someone who could help me? Thank!
1
vote
1answer
500 views

How can I obtain Wolfram Alpha's “alternative forms” of an expression inside Mathematica?

When I type in Wolfram Alpha, say, cos(a+b) or cos(a+b)^2 or (OK this next one can easily be obtained in Mathematica, ...
2
votes
1answer
232 views

Segment parts of a picture

I remember that there was some thread of this sort, but I could not find it, so I hope it's ok to open a new thread. I want to segment pictures of the brain, i.e. I only want the area within the ...
1
vote
1answer
67 views

Devising a sparse array rule

Suppose I have a matrix A={{1, 2}, {3, 4}} that defines the positions of non-zero values in a sparse array: ...
8
votes
2answers
340 views

Mathematica outliner's capabilities

As my notebooks get larger, I often try to organize them with titles/subtitles etc, structuring them as an outliner (http://en.wikipedia.org/wiki/Outliner) This also helps me as I try to structure a ...
0
votes
1answer
101 views

Solving a differential Equation

I am trying to solve -D[((α + γ/2)*a + β/(2*a) - R*a^3)*p[a], a] + 0.5*D[(γ*a^2 + β)*p[a], {a, 2}] == 0 with DSolve, but it ...
0
votes
0answers
301 views

NDSolve gives wrong results for “stiff system”

I have a physical problem in which I want to solve for c[e] as a function of e, where c is ...
0
votes
0answers
58 views

Expectation taking unusually long to evaluate

I am trying to evaluate an expectation, but it is taking an extremely long time although the expression itself should not be too complicated. My code is ...
0
votes
1answer
135 views

Using a LocatorPane

I have a network of a power grid where the edge are the power lines and the vertices are loads or generators. I was wondering how I can import an image into Mathematica to derive some sort of ...
3
votes
0answers
62 views

What SampleRate and SampleDepth does Mathematica use on output?

The Play function will happily accept arbitrary values for its SampleDepth and SampleRate ...
5
votes
3answers
245 views

How to change the number of markers in Plots?

Two questions, but I am not sure whether they are already answered or not. How can I create PlotMarkers (in ListLinePlot) with ...
0
votes
3answers
486 views

Solving One Equation with Two Variables

I am trying to solve an equation with two variables. It is the last step in the process of using the method of undetermined coefficients to solve a nonhomogeneous differential equation. The equation ...
2
votes
1answer
166 views

Compute symbolic Expectation of a summation

I am required to computed following Expectations : $E[\displaystyle\sum\limits_{i=1}^N \frac{X_{i}}{N}] = \bar{x}_{0}$ & $E[\displaystyle(\sum\limits_{i=1}^N \frac{X_{i}}{N})^2] = ...
2
votes
1answer
98 views

Can I use Map here rather than Table?

I've got something that works, but it seems like it would be "nicer" if I didn't have to use Table (or For, etc.). I've got 3 Excel files, each with multiple sheets. Each file also has a sheet ...
0
votes
0answers
82 views

Using Wolfram Language without Raspberry Pi [duplicate]

What are the different ways I can start using Wolfram Language even though I dont want to use Raspberry Pi? Are there any convenient ways? I actually have a raspberry pi but I am trying to find ...
7
votes
1answer
326 views

CompilationTarget->“C” crashes the kernel

Major deviation from my original post I realize that the long code I originally had was very discouraging to debug and did not attract any answers. So I have decided to revamp this question ...
3
votes
1answer
75 views

Extract differential operator from differential form

Let's say I have : a*u''[x]+b*u'[x] where a and b are constant I would need to get ...
4
votes
2answers
154 views

Replacing one element of list

I have a list of sequences of x's and y's. I want to switch the last position to the "opposite" symbol - if ...
2
votes
1answer
175 views

Simplify results further

I have an extremely long result in polynomial form following some matrix operations. However, given the symmetry of the problem, I can safely say that the solution will reduce much further than is ...
4
votes
3answers
138 views

Is there an equivalent of Sum for And?

Is there an equivalent to Sum for And? That is, just like instead of ...
4
votes
6answers
526 views

ParametricPlot with plot markers

I have a parametric plot, and would like to fit a line to it with "■" PlotMarkers on it, but am unable to do so. ...
6
votes
3answers
217 views

Finding the position of similar elements in a matrix

I want to find the position of the elements which are equal in a matrix. For example in the case of the following matrix: $m =\left( \begin{array}{cc} a & x \\ x & a \\ \end{array} \right)$ ...
1
vote
1answer
362 views

Hiding the Code in .CDF File

I downloaded the source code of a demonstration and modified it. Then saved it as a CDF file. When I re-opened this file (in Mathematica or CDF Player), all of the code can be seen. How can I hide the ...
0
votes
1answer
120 views

How to find a fit for a function?

I have the following function: ...
0
votes
1answer
74 views

How to evaluate Floor[1/2 + Arg[z]/(2π)] with Re[z] > 0

I want to do a series expansion of an expression containing Gamma functions with specific arguments. An example is the following: ...
2
votes
2answers
94 views

How to combine notebook into one cell

I want to have my entire notebook be a conditional while statement. However, I don't want to merge all of my cells together, as it is a long and detailed process. Is there a way to create another cell ...
0
votes
2answers
180 views

How to control the layering of graphics displayed with Show

I am trying to combine two graphics objects using Show. The first one is an isosurface: ...
11
votes
5answers
450 views

How would you efficiently implement BinListsBy?

Let's say I have a list like this: data = {{21, "Alice"}, {27, "Bob"}, {22, "Charles"}, {34, "Dora"}, {75, "Eliza"}} containing ages and names of persons. What I ...
3
votes
1answer
58 views

Strange NSum behavior for slightly larger number of terms

For some sums, NSum gives me the result nicely for some number of terms, but if I add one more term, it suddenly becomes much slower. I haven't found the minimum example for which this can be ...
1
vote
1answer
92 views

Prohibiting Autorun in a Manipulate?

One of the four possible AppearanceElements for Manipulate is "ManipulateMenu" which provides a number of features such as ...
1
vote
0answers
34 views

Determine Functions Given Data Points [duplicate]

Is it possible for Mathematica to solve for f(x,y) = 0 such that {x,y} contains {{0,0.5}, {1,0.5}, {0.6,0.8}, {0.4,0.2}} ? Do we need to specify f(x,y) first ? ...
0
votes
1answer
106 views

Put a rounded parentheses in a label [duplicate]

I have this plot: ...
1
vote
2answers
84 views

Using Combinatorica`ListNecklaces in v9

I am using Mathematica for visualization of DeBruijn graphs. However, I am having a bit of trouble using ListNecklaces. I want to know how many cyclic shifts of ...
3
votes
1answer
306 views

How to map vertex points from the surface of a straight pipe onto 2D plane

How to map vertex points from the surface of a straight pipe onto 2D plane. The 3D surface points of the straight pipe can be found here: data Working code: ...
0
votes
0answers
100 views

Failing to get a coloured coordinate in 4D plot

I am trying to get a colour data plotted according to a coordinate. I am working with 4D vectors, with three spatial and one temporal coordinate. I tried the accepted answer at Plot 4D data with ...
0
votes
1answer
106 views

Help with Computation-heavy triple integration

I'm Trying to use Mathematica to symbolically integrate a function with respect to x, y, and z. For some reason, this computation either takes about, 60s and returns the input, or takes many hours ...
2
votes
0answers
60 views

Natural boundary conditions variational methods

I am working on a problem of the calculus of variations. From the Variational Methods package, I can very conveniently use EulerEquations to get stationarity ...
3
votes
0answers
207 views

Understanding performance: graph connected components

I need to analyze directed graphs with 10M edges, 1M vertices, and 300K strongly connected components, so that the largest one contains 400K vertices. I read some explanations of Leonid Shifrin here, ...
6
votes
1answer
127 views

Why PlotRange doesn't work for this set of values? [duplicate]

This code, doesn't show me data corresponding to x axis values 1000 and 10000 ...

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