16
votes
1answer
306 views

Copying one symbol into another

I would like to know how can I completely copy one Symbol to another. When I say copy, a refer to UpValues, DownValues, ...
13
votes
1answer
356 views

Is it possible to use Begin and End inside a Manipulate?

May be someone can explain why I can't use Begin["context`"] and End[] inside a Manipulate ...
16
votes
3answers
2k views

Plotting piecewise function with distinct colors in each section

I have a piecewise function that I would like to plot but I was wondering if it is possible that each part of the function that is plotted when its corresponding condition is true be plotted with a ...
12
votes
2answers
644 views

How to extract the numerical value of a dynamical variable

I want to inspect interactively an image by selecting points by the mouse pointer. This is easily done by LocatorPane - here is a simplified example: ...
5
votes
1answer
1k views

Mathematica won't give eigenvectors but Wolfram Alpha will? What am I doing wrong?

If I ask Mathematica to find the eigenvectors and eigenvalues of the matrix: ...
5
votes
1answer
872 views

How Can I use Solve/Reduce Output

Suppose I want x and y to be rationals Solve[ x^2 + y^2 == 1, {x, y}, Rationals] I am ...
5
votes
3answers
540 views

Retrieving the ImagePadding in absolute units

Consider the following graphic: g = Graphics[Circle[], Frame -> True, FrameLabel -> {"one", "two"}] Retrieving the ...
12
votes
3answers
934 views

Why is ContourPlot not displaying this curve?

I am using the general form of a second-degree plane curve: $$Ax^2+2Bxy + Cy^2+2Dx + 2Ey + F = 0$$ I want to randomly generate plane curves of this form, so I am using ...
9
votes
6answers
353 views

List-operations only when restrictions are fulfilled (Part 1)

Consider the following: ...
7
votes
2answers
662 views

Automatically load packages at startup

I'm a physics student and I try to simplify my day with Mathematica. Every time I use Mathematica I need Div[], Grad[], ...
4
votes
3answers
294 views

How can I compare a dynamic variable with a literal in Mathematica?

I'm doing a Mathematica Notebook and I want to make an alarm clock. Something like this: ...
2
votes
2answers
224 views

Position function not always retuning an answer even with no apparent problems

I'm having some problems with Position. Sometimes it will give an empty list instead of the actual position of the element I am looking for when that element is ...
93
votes
3answers
12k views

How to create word clouds?

Word clouds are rather useless fancy and visually appealing plots, where words are plotted with different sizes according to their frequency in a corpus. Many applications exist out there (Wordle, ...
67
votes
4answers
5k views

How to peel the labels from marmalade jars using Mathematica?

How can I detect and peel the label from the jar below (POV, cylinder radius, jar contents are all unknown) to get something like this, which is the original label before it was stuck on the jar? ...
60
votes
8answers
12k views

How to make an inkblot?

How to effectively create a polygon that looks like a realistic inkblot? So far, I could come up with this (borrowing from Ed Pegg Jr.'s Rorschach demonstration): ...
38
votes
2answers
1k views

Mathematica Debuggability

One of the things that I really dislike about Mathematica is its lack of debuggability compared to many other programming languages. Some of the problems arises from the functional nature of ...
42
votes
3answers
1k views

When I can assume that all decimal digits returned by Mathematica are provably correct?

How to Control the Precision and Accuracy of Numerical Results Arbitrary-Precision Numbers Mathematica works with exact numbers and with two different types of approximate numbers: ...
39
votes
5answers
4k views

How do I plot coordinates (latitude and longitude pairs) on a geographic map?

I'm attempting for the first time to create a map within Mathematica. In particular, I would like to take an output of points and plot them according to their lat/long values over a geographic map. I ...
33
votes
3answers
1k views

How to distribute proprietary Mathematica code

If I want to make package-code completely unreadable, in a way that the end-user can only call my functions, but has no way to re-engineer my definitions, how would I do that? I know I can use ...
20
votes
2answers
1k views

Debugging memory leaks

I've written my incredibly complex, incredibly elegant analysis function, that works great on small test data. But when I run it on my real (bigger) data set it keeps running out of memory. It turns ...
32
votes
1answer
1k views

Generating a table of contents

This is my oldest question on SO. It still hasn't generated a useful answer there, so I thought I'd give it a try here. The question was: I don't seem to be able to find the method to generate the ...
34
votes
3answers
2k views

How to find out which method Mathematica selected?

There are commands like NonlinearModelFit[] or NDSolve[] that have the option Method it ...
30
votes
6answers
1k views

How to visualize/edit a big matrix as a table?

Is it possible to visualize/edit a big matrix as a table ? I often end up exporting/copying big tables to Excel for seeing them, but I would prefer to stay in Mathematica and have a similar view as in ...
28
votes
5answers
2k views

Are there any cases when For[] loops are reasonable?

To my mind the only reason for the existence of For[] loops in Mathematica is to allow new users with some experience in procedural programming languages to write ...
25
votes
4answers
6k views

How to use Mathematica functions in Python programs?

I'd like to know how can I call Mathematica functions from Python. I appreciate a example, for example, using the Mathematica function Prime. I had search about MathLink but how to use it in Python ...
22
votes
4answers
3k views

Computing and plotting a spectrogram in Mathematica

How can I compute and plot the spectrogram of a signal/time series/data in Mathematica? I have a WAV file, sampled at 44100 samples/second and I want to generate a spectrogram of that data. Something ...
16
votes
5answers
6k views

Estimate error on slope of linear regression given data with associated uncertainty

Given a set of data, is it possible to create a linear regression which has a slope error that takes into account the uncertainty of the data? This is for a high school class, and so the normal ...
32
votes
5answers
746 views

Items known by CurrentValue

CurrentValue can be used to poll the state of numerous system values such as the mouse position. Its help page doesn't list all possible items, though. An item like ...
19
votes
1answer
726 views

Programmatically move the cursor to a desired location on the screen

Is it possible to set/move the mouse pointer's location directly from Mathematica without using external tools like Run["xdotool mousemove x y"]?
26
votes
6answers
2k views

Extruding along a path

I'm trying to render a 3D image of a path by extruding a circular cross-section along the path, creating a "snake-like" path. Here is an image I found to illustrate: I can't seem to figure out if ...
24
votes
4answers
896 views

What tools can help in realizing tail recursion?

I had nice discussions with Leonid and Rojo that got me interested in tail recursion. Tail recursion is not always easy to realize with Mathematica, so it would be nice to have some tools to help with ...
10
votes
2answers
2k views

How to calculate contour integrals with Mathematica?

How to calculate the integral of $\frac{1}{\sqrt{4 z^2 + 4 z + 3}}$ over the unit circle counterclockwise for each branch of the integrand?
21
votes
7answers
3k views

Changing the background color of a framed plot

I frequently generate framed plots like this: Plot[Sin[x], {x, 0, 2 \[Pi]}, Frame -> True] Is there an easy way to change the background color of the framed ...
16
votes
3answers
633 views

Create an adaptive amount of local variables for error propagation

I intend to write a function which calculates the result and the error for any formula with any amount of variables using the Gauß Error Propagation. The error $\mathrm{d}R$ for a function $R(a,b,c)$ ...
16
votes
5answers
1k views

How to speed up the function DelaunayTriangulation?

First define a function meshGrid to generate some points: ...
13
votes
1answer
2k views

Vertically aligning two separate plots

How do I vertically align plots so that the two plots are displayed in a way that lines up with respect to the axes? The code I have so far is: ...
23
votes
6answers
1k views

Faster alternatives for DayOfWeek

It has been noticed on several occasions that DayOfWeek function is rather slow when applied to a large list of dates, e.g. in this recent question. What faster ...
18
votes
4answers
853 views

How to collect result continuously (interruptible calculation) when running parallel calculations?

This is the most common pattern to compute a table of results: Table[function[p], {p, parameters}] (regardless of how it's implemented, it could be a ...
26
votes
2answers
821 views

Transpose uneven lists

Is there a quick method to transpose uneven lists without conditionals? With: Drop[Table[q, {10}], #] & /@ Range[10] Thus the first list would have the ...
18
votes
2answers
448 views

Implementing a safe ValueQ that does not evaluate its argument

Mathematica has a built-in function ValueQ. Quoting the docs, ValueQ[expr] gives True if ...
12
votes
7answers
2k views

How do I replace a variable in a polynomial?

How do I substitue z^2->x in the following polynomial z^4+z^2+4? z^4+z^2+4 /. z^2->x ...
15
votes
4answers
2k views

Plotting several functions

I'd like to plot a function of one real and one integer variable, but I don't want them all shown in the same 2-D plot - I'd like to see them as separate curves so I can see both 'axes', more like ...
14
votes
1answer
7k views

Is it possible to export the equations from Mathematica to MATLAB?

Is it possible to export the output expressions from Mathematica computations (e.g., equations) in valid MATLAB syntax?
7
votes
3answers
2k views

Given a Table of Plots with some parameter, how would I mark each of the plots with that parameter

I've got a two variable function that I'm plotting against one axis for a few different values of a parameter ...
14
votes
4answers
469 views

Returning an unevaluated expression with values substituted in

Let's say I have a function formula[x_List] := (x[[1]] - x[[2]]) + (x[[3]] - x[[4]]); and I want to pass it a variable and get back the unevaluated formula with ...
11
votes
4answers
517 views

How to automate a FrontEnd return?

I use some custom shortcut keys in KeyEventTranslations.tr. One is for the Delete All Output function: ...
5
votes
3answers
727 views

Quickly editing the stylesheet and saving it

I have a private stylesheet I'm using. I edit it by going to the menu Edit->Edit Stylesheet and then clicking on the private stylesheet cell. I can modify whatever I want but it never gets saved. The ...
16
votes
2answers
829 views

How do I perform string matching and replacements?

What are, and how do I use Mathematica's string matching and replacement tools?
16
votes
5answers
1k views

Having the derivative be an operator

How do I create an operator which acts like a derivative to everything to the right of it: for example: $ \left( \partial_x + \partial_y + z \right ) x \psi $ How do I make that evaluate to: $x ...
12
votes
3answers
1k views

How do I use Map for a function with two arguments?

I'm a newbie who tries to be a good boy, and use Map instead of writing out a list of functions. I have a table I want to Map ...

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