4
votes
3answers
208 views

How to compile a diagonal array efficiently?

For example, if we use some functions defined prior to Compile, we usually have the main evaluators in the compiled codes, pointing to the definition of the ...
4
votes
4answers
551 views

Replace For-loop with functional code

I am very new to Mathematica. I have code written using for loops. I want to rewrite it using Map/Thread but I am not sure how ...
4
votes
1answer
174 views

Alternative updating of a dynamic expression

I am looking for a solution to selectively update a dynamic expression expr which is dependent on multiple control variables ...
4
votes
2answers
610 views

Transparent Cylinder with Dashed Edges only

I would like to have that kind of cylinder with Dashed edges (including the bellow inner ring): I've been trying that: ...
4
votes
1answer
981 views

Non-commutative algebra

I'm constantly dealing with non-commutative algebras. ** is inbuilt, non-commutative and associative. That's good :-) But it is not distributive. Rats. ...
4
votes
1answer
310 views

Execute code when file is modified

I have a function the takes some time to complete. The function imports data from a .csv, parses it, and plots certain vectors from there. The .csv is constantly being updated from an external ...
4
votes
1answer
927 views

ListPlot3D - How to make the Color depending on a second list

From a simulation (solid state physcis) i obtained a list1={{300,0,0},...} with x values=300,400,...,1500 and y-values=0,0.08,...,20 and z values. I plotted them ...
3
votes
2answers
357 views

Replacing gamma at half integers by double factorial

It is well-known that for any positive integer $n$ the equality $\Gamma(n+\frac12)=\sqrt\pi\,(2n-1)!!/2^n$ holds, where $!!$ stands for the double factorial. I am using ...
3
votes
2answers
867 views

How to Plot Prism in Graphics3D

I want to create an image of a rectangular prism, but there is no built-in primitive for it. One method to display a prism is shown in whubers's answer to Mathematica for teaching orthographic ...
3
votes
2answers
659 views

All possible solutions to the Matrix Equation (free variables appearing)

I am attempting to solve a system of linear equations using LinearSolve[] . In my case, the number of unknowns are more than constraints. I learnt that LinearSolve ...
3
votes
1answer
877 views

Interpolating 2D data with missing values

I have a list (21 x 21) containing values. I want to eliminate slots containing zeros by interpolating the nearest values and overwriting the zeros. How do I use the Mathematica's ...
3
votes
1answer
325 views

What's the correct method to simplify exponentials?

I have a sum of exponentials that I'd like to simplify. The issue is when I use Simplify, Mathematica loves to factor out one exponential factor. See below: $$e^{-i ...
2
votes
2answers
804 views

How can I get even steps on x and y axes in a plot?

I'm plotting the shortest distance from a point to a line using the following code ...
2
votes
1answer
3k views

How do I troubleshoot when I get a Part::partd or a Part::partw error?

Mathematica has produced the following error message: Part::partd: Part specification ... is longer than depth of object? What is partd? I think I may ...
1
vote
3answers
349 views

Replace with position and order number

question conversion1 : Convert "[AA]AB[AA]BB[AA]B[AA]CCC" to "[A1A2]A3B1[A4A5]B2B3[A6A7]B4[A8A9]CCC" conversion2 : Convert ...
20
votes
1answer
379 views

Excessive memory use by Mathematica kernel in 10.0.2 after executing simple commands

Warning: the code below may hang your system if you have the Suggestions Bar enabled. When issuing the following simple statements to Mathematica, it responds with a valid answer. However, ...
17
votes
4answers
470 views

Getting lengths of sublists that sum to more than one

I have a long list of numbers, and I'm interested in finding the length of each sublist that totals to more than 1, so for the list ...
16
votes
2answers
835 views

Plot Option Precedence while combining Plots with `Show[]`

I like to build sophisticated plots by combining simpler ones with Show[]. Typically this involves setting non-default Plot-Options with the different ...
15
votes
1answer
309 views

Adding three integer sparse matrices is very slow. Adding only two is fast

Adding more than two sparse matrices in one step in Mathematica 9 is very slow (in fact I couldn't even wait for it to finish). Here's an example. Let's generate a large sparse matrix: ...
14
votes
7answers
688 views

How to use Union on list of lists without sorting them first?

If I do ClearAll[a, d] lsts = {{a, d}, {a, d}}; Union[lsts] I get the expected answer {{a, d}} but if I do ...
12
votes
1answer
2k views

What method does NDSolve use for solving PDEs?

What is NDSolve's mode of operation? I use it to solve partial differential equations and never gave it too much thought. Recently, I came across this question. ...
11
votes
1answer
262 views

Bizarre behavior of With, Compile and Break

I'm guessing this is almost certainly a bug in Compile (because they're fairly common), but it's pretty weird and I spent about an hour tracking down the issue and ...
11
votes
4answers
339 views

How to replace every possible $A+B$ and $AB$ in expansion of $(A+B)^{10}-A^{10}-B^{10}$ with $x$ and $y$, respectively?

I would like to replace every possible $A+B$ and $AB$ in expansion of $(A+B)^{10}-A^{10}-B^{10}$ with $x$ and $y$, respectively. How to do it with the simplest code in Mathematica? For example, ...
11
votes
3answers
190 views

Why can't I use Sequence to perform a Select like task? [duplicate]

Suppose I wanted to write down a list of $p^2$, for $p$ a prime between $1$ and $20$. I would expect Table[If[PrimeQ[k], k^2, Sequence[]], {k, 1, 20}] to work. ...
11
votes
4answers
688 views

Ordering vertices in GraphPlot

I'm new here, so forgive me if this question is not well-posed/duplicates an earlier question - although I've searched for similar questions without success. I'm trying to present a plot of ...
11
votes
5answers
409 views

TableAlignments -> Left not working

Bug introduced in 7.0 or earlier and persisting through 10.0.2 or later For a very simple dataset TableAlignments->Left does not work: ...
11
votes
3answers
596 views

Delete duplicates in a list, depending on the sequence of numbers

Below, list is a representative sample of my list, which contains lists of integers. I would like to be able to input: ...
10
votes
3answers
105 views

Resizing or moving Notebook window causes Manipulate to update its argument

Check this example: Manipulate[Grid[{{RandomReal[10]}, {Plot[Sin[x], {x, 0, 2 Pi}]}}], {a, 1, 3}] As you can see, moving or resizing the Notebook window causes ...
10
votes
3answers
491 views

Non-geometric transformation of Graphics3D primitives

I want to apply non-geometric transformations to polygons etc, the goal is to have a Manipulate objects that behaves like that famous möbius transform video. Since ...
10
votes
2answers
1k views

Non-commutative symbolic linear algebra

I am fairly new to Mathematica but I thought I would be a helpful tool to carry out a few simple linear algebra calculations. It seems like an easy task but I cannot figure out how to do it. For ...
10
votes
1answer
1k views

Where can I permanently modify $Path?

I've quite forgotten: what file does one modify in order to add directories to $Path globally? Specifically, I want to include ...
9
votes
2answers
394 views

Nest , Fold … is there an extension for more than 2 arguments?

Fold is an extension of Nest for 2 arguments. How does one extend this concept to multiple arguments. Here is a trivial example: ...
9
votes
2answers
719 views

Import tweets from Twitter

Robert Raguet-Schofield in the Mathematica Blog introduced a way to import tweets from Twitter into Mathematica. I attempted to use this method. I started with this line of code: ...
9
votes
3answers
294 views

substitution rules excluding subscripted variables

Suppose I have an expression containing p,Subscript[p,1],Subscript[p,2],etc. I want to ...
9
votes
3answers
2k views

Simplify expressions with Log

How can I get Mathematica to simplify the following expression n Log[a] + m Log[b] - m Log[a + b] - n Log[a + b] into ...
9
votes
1answer
3k views

Complex number operations: telling Mathematica variables are real

I want to do Conjugate[a + b*I], but when I do that, the solution is Conjugate[a] - I*Conjugate[b]; when for me, a and b are ...
9
votes
1answer
329 views

Selectively clear DownValues

How can I clear a subset of a symbol's DownValues ? For example, suppose I have created some DownValues for $f$ like this: ...
9
votes
3answers
306 views

Find variable name from DumpSave on a scoped variable

I saved an InterpolationFunction in a ".mx" files using DumpSave on a variable that was scoped by a ...
8
votes
3answers
1k views

Pass list of options to Plot3D

Consider the example plotOptions = {PlotPoints -> 10, MaxRecursion -> 2} Plot3D[x y , {x, 0, 10}, {y, 0, 10}, plotOptions] Why does this causes the error: ...
8
votes
1answer
266 views

Antialiasing of horizontal lines

Consider the following graphic: g = Graphics[{Circle[], Table[Line[{{-1, i}, {1, i}}], {i, -1, 1, 0.2}]}, ImageSize -> 150] (You may need to look directly ...
8
votes
2answers
160 views

Substituting confidential tagged cells by a “content removed” cell

When producing a notebook with both code and text, I often end up with pieces of code, or even entire chapters, that I don't want to be shown on the final output. I generally hide or close them by ...
8
votes
2answers
2k views

Convert a string to hex number?

How can I convert a string containing a hex number such as "6b" to a hex digit that mathematica can use to do math with? I have tried using ...
8
votes
5answers
5k views

How to get rid of warnings when using Solve on an equation with inexact coefficients?

When I solve this equation in Mathematica 8, I can get the right answer, but with some uncomfortable warnings. Equation: ...
8
votes
3answers
5k views

Plotting Partial Sums of Fourier Series

I'd like to plot some partial sums for a Fourier Series problem, but I am not sure if the output I am getting is correct. I want to be able to plot the partial sums and the function on the same graph. ...
8
votes
1answer
6k views

Adding a point to an already existing graphic

This is just a follow-up of this post: Beginner 2D animation with maths equations Part of the code is: ...
7
votes
2answers
173 views

How to make Inset graphics maintain relative sizes when combined

I am learning a little about Inset, but after trying all options, I can't get this to work. I need to inset separately made Graphics2D objects, into one main ...
7
votes
4answers
549 views

Solving $L=\frac{3}{2} \sqrt{4 \pi ^2 A^2+W^2}-\frac{\sqrt{5 W \sqrt{4 \pi ^2 A^2+W^2}+6 \pi ^2 A^2+3 W^2}}{\sqrt{2}}+\frac{3 W}{2}$ for $W$

When I solve the aforementioned equation for $W$ or $A$ on Mathematica I get a long and ugly equation in return, namely one of the solutions for $W$ is: (attempt to read at your own health) ...
7
votes
6answers
1k views

How to make a resizable chess board?

For some reason I need to create a chess board. I can create a chess board by following command: ...
7
votes
1answer
330 views

transparency in image used for texture?

Is there a way to set a transparancy channel in a raster image used for a texture in 3d graphics? this creates a raster image with a transparency channel: ...
7
votes
2answers
562 views

UNIX time to DateList

I have data that is timestamped with UNIX time, which is the number of seconds since January 1, 1970 UTC. Unfortunately, it seems that most of the date and time functions in Mathematica are based on ...

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