# All Questions

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### Problem with distinguishing terms in a sum

I am doing a sum and the code for this is given as ...
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### Notebook cells space on disk profiler

I have one single notebook with more than 500 mb... To control its growth, I would like to have a profiler of used space (not the live memory, but the space on disk), in such a way that I can easily ...
88 views

### Simplifying expression with non-commutating entries

Say I have an expression such as (a + X)**(b-Y) where the variables above possess the following commutation relations [a, b] = [a, X] = [a, Y] = [b, X] = [b, Y] ...
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### Why does FreeQ seem not to work with complex numbers?

I guess I do not understand how Mathematica evaluates this simple expression inside FreeQ ...
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### How to specify frame tick labels without modifying the Automatic tick marks? [duplicate]

I have the following: ...
228 views

### Copy/Pasting a Grid of Numbers from Project Euler

On Project Euler Problem 11 (link: https://projecteuler.net/problem=11), there is a 20x20 grid of numbers. However, when I pasted it into Mathematica, I got this strange result where the times symbol ...
154 views

### Matrix with known entries but unknown size [on hold]

I am trying to perform some calculations with a matrix that has let's say size N but unknown, please How can I write this in mathematica?
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### How can I get the vertex labels of an existing graph?

For example, if there is a graph g = CompleteGraph[5, VertexLabels -> {1 -> "v1", 2 -> "v2", 3 -> "v3", 4 -> "v4", 5 -> "v5"}] How can I later ...
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### Can the increment in Manipulate, Table, Range, etc. be subject to an If statement?

In this demonstration I'm working on, I would like to plot a piecewise function with the tangent line to the function at a point that is determined by c in the code ...
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### Where can I access documentation for old versions of Mathematica?

Some documentation of functions available in old versions of Mathematica (and old packages) is available online, e.g. http://reference.wolfram.com/language/Combinatorica/ref/Vertices.html Is there ...
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### Calculating $\lim_{x\to 1} \, \int -\frac{i \text{Li}_2\left(x-x^2\right)}{\sqrt{3} \left(x-\frac{1}{2}-\frac{i \sqrt{3}}{2}\right)} \, dx$

How can we force Mathematica to compute this limit? $$\lim_{x\to 1} \, \int -\frac{i \text{Li}_2\left(x-x^2\right)}{\sqrt{3} \left(x-\frac{1}{2}-\frac{i \sqrt{3}}{2}\right)} \, dx$$ It seems it ...
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### How to use NDSolve to solve the system of differential equations? [on hold]

Reference: Mathematical model for HIV/AIDS with complacency in a population with declining prevalence from http://downloads.hindawi.com/journals/cmmm/2006/471467.pdf I found the differential ...
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### Compute complete graph and make minimum spanning tree

I'd like to plot a complete Graph and then compute the Minimum spanning tree of it. I already can make a complete graph out of a list that countrydata gives me: ...
108 views

### How to export images in EPS format that can be opened in CorelDraw

I am preparing a paper. The journal requirements are odd: only eps files for pictures are accepted. All pictures I have drawn in Mathematica and exported in eps format in the usual way: ...
43 views

### Comments including LaTeX commands in Mathematica [duplicate]

I want to write some comments in Mathematica - which include LaTeX commands - using the form ...
104 views

### How to check the option value?

Given that I have a function func as follow: To check the value of options, I using the step-by-step method If[] ...
187 views

### How to Apply Functions to Lists with Many Curly Brackets?

For example, consider the list defined below. samplelist = {{{1,2,3,4}}, {{5,6,7,8}}}; How would I apply the Times operator ...
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### FoldList[Union,…] version 8 vs version 9 [duplicate]

I have a list of matrices something like shown below A = {{{1,1,1,1,1},{2,2,2,2,2}},{{3,3,3,3,3},{4,4,4,4,4},{5,5,5,5,5}}} When I try to run the code ...
164 views

### Why does my calculation of a probability take too much time?

I am calculating the value of the following function for given argument values: ...
50 views

### Functions becoming undefined when evaluated

I'm so confused I don't even know how to phrase my Question title. My function nextCol works until I use colLength, then ...
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### Faster use of Condition for a large array (see the example)

Here is the example/problem. I have a array of $n$ random number. n = 2000; p = RandomReal[{0, 9}, n]; I have to create a $n\times n$ sparse matrix with ...
45 views

### Solving a system of nonlinear equtions [on hold]

I'm trying to solve a system of nonlinear equations which consists of 12 variables and 12 equations. A solution is obtained, but with an error. FindRoot::lstol: The line search decreased the step ...
36 views

### Why doesn't Mathematica support Import for SWF files? [on hold]

Why doesn't Mathematica support Import for SWF files? I saw that Mathematica can export to .swf, but I wonder why it does not import .swf files?
45 views

### Building Pythonic Programming style to Mathematica with visually-accessible list comprehensions?

The question List comprehension in Mathematica has comment about this Functional style using lazy lists? where they build some sort of style for lazy lists: I understand it so that it is impossible to ...
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Example: ...
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### Building up a sequence dealing with a complex recursive scheme

Suppose I have multiple lists, the first one contains 2 elements, the next one 4 elements, the next one 8 elements, and so forth. Let these elements be labeled as Gij where i refers to the list it ...
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### Optimization over 6 vectors

Suppose I have an expression which depends on 6 unit vectors (3 dimensional). Hence, I need to optimize over 12 parameters (every vector contains 3 parameters, but one we can reduce by considering ...
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### How to tell Mathematica that my variable is a scalar

In my calculations I have these combinations PauliMatrix[1].f PauliMatrix[2] where f is a scalar function. The result is as ...
65 views

### How to get the size of a specific image in the front end?

The title pretty much says it all. One possible point of confusion is that this question is not limited to items with head Image. I don't know what is the ...
72 views

### How to scale multiple graphics to preserve relative sizes?

I'm looking for a simple way to make the displays of different Graphics expressions accurately reflect their relative sizes. (By "simple" I mean that it does not ...
74 views

### Conditional subset generation

I am trying to accomplish the following task: Given a list of coordinates of n points in the plane, I need to find subsets of all points that share the same ...
198 views

### Drawing a ladder graph with Line and Table/Array

I want to programmatically draw a ladder graph like the one below: I'd like to use Table to dynamically add steps. My (lame) attempt so far: ...
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### Labeling a ListPointPlot3D

I've a problem with the label of ListPointPlot3D. I tried to reproduce a plot I've seen in a paper, but I was not able to reproduce it completely. Following and example of my data: ...
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### Non Linear Model Fit (Division by Zero Error Message)

Can someone please tell me why this expression returns error messages about division by zero. ...
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### Numerical minimization hangs at some steps

Let me briefly explain what I observe and cannot really explain by myself. I occasionally use NMinimize to find optimal parameter sets and sometimes it happens that ...
143 views

### Von Kármán Vortices

How may we vary vectors in StreamPlot[{y, -Sin[x/2]}, {x, -4, 12}, {y, -4, 4}, StreamColorFunction -> "Rainbow", AspectRatio -> Automatic] to obtain a ...
131 views

### How to retrieve current FaceForm?

The current colour in a Graphics object can be retrieved using CurrentValue["Color"] for use in Dynamic stuff. Example: ...
45 views

### Saving numerical values to a *.dat file

I have a function like this: ...
52 views

### The Summation of a Summation in Mathematica

I am trying to input $\sum_{a_1=1}^{n-1}$$\sum_{a_2=1}^{{a_1}-1}$$\sum_{a_3=1}^{{a_2}-1}$$\sum_{a_4=1}^{{a_3}-1}$$...f({{a_1},{a_2},{a_3},{a_4}...})$ into Mathematica. The number of sums should be a ...
62 views

### Iterative Tree Plot for the Sum of an Integer's Digits Squared

I am trying to make a graph that depicts integers<100 mapping to the sum of their digits squared. I can do this for one iteration, but I don't know how to do it for more than one, or until the new ...
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### Remove line breaks or return codes from string

I have imported string data, which appears to have line breaks or return codes in it invisible in a notebook input cell. Copying a string and pasting into Apple Pages with control codes showing gets ...
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### Compiling FoldList implementation for RK4

Original I'm looking to write an integrator for a function of two variables. Here is my implementation for the RK4 update rule using FoldList. ...