Questions on writing non-trivial programs in Mathematica. Do not use this tag for questions on plotting/graphics or for questions on doing mathematics with Mathematica, where the focus is more on the math than the program.

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8
votes
3answers
244 views

Grid without lines, but with dots

I want to build a grid to look like the top-left table shown below, but without an outside frame. Here is what I've tried to do: ...
8
votes
1answer
100 views

CSS Selectors for Symbolic XML

Symbolic XML is a convenient way of managing XML in Mathematica, at least for casual use or small tasks. Here and elsewhere you can find examples of XML handling in Mathematica, including XSLT/XPath ...
8
votes
3answers
301 views

Patternmatching sets

How to match set-patterns against sets? A set (in the mathematical sense) is a list of elements without repetition and order of elements does not matter. For example, we have a pattern set ...
8
votes
2answers
227 views

Cases[data,Colon[key,_]] vs. Cases[data,key:_] toward XPath, XQuery

Exploring methods to index and search tree-structured key:value pairs via named-entity index (key paths) as opposed to Position-based indexing. Using Rule as ...
8
votes
4answers
393 views

Best way to modify values in a list of rules?

Recently I had to solve a problem similar to this: Let's say I have a list of list of rules ...
8
votes
2answers
261 views

Restrict Sensitivity of Locators in LocatorPane

We can restrict the movement of locators in a LocatorPane as follows: In the following example, the first locator's movement is confined to the x-axis and the ...
8
votes
1answer
290 views

What is a good coding style for setting and changing application level constants?

Background: Every application has user-definable constants. The Java language has the Properties class to handle them. Question: What is a good and re-usable coding style for setting and changing ...
8
votes
1answer
302 views

Why does Mathematica choose the second function definition?

While working on a solution to this question I've come across a case where I simply don't understand Mathematica's behaviour. I've got the following definitions: ...
8
votes
1answer
335 views

Abort not aborting

I have a relatively simple bit of code that looks like the following: ---some code here--- If[statement, Abort[]]; ---more code following--- However, while ...
8
votes
1answer
120 views

Is it possible to use the global definition of a symbol as part of its new local definition set in a Block?

Consider the following expression: Block[{Print = CopyToClipboard}, doSomething[]] Now all calls to Print from ...
8
votes
1answer
171 views

How can I make CurrentValue for font characteristics pick up the font of the output not the input cell?

The command CurrentValue (documentation) allows you to access various properties of fonts, such as x-height, line height, and various measures of width such as ...
8
votes
2answers
752 views

How to calculate mix of 4 colors defined in CIELAB L*a*b* model?

I have 4 colors that I converted from RGB to CIELAB L*a*b* model. How can I calculate mix of these 4 colors when I have (L,a,b) for each such color? How can I ...
8
votes
1answer
132 views

Is it possible to write a function immune to symbol redefinitions in any Block surrounding its invocation?

Normally, semantics of symbols used in a function definition can be changed by their redefinitions in Blocks surrounding the function invocation: ...
8
votes
1answer
728 views

(Non-Convex) Polygon Union and Intersection Functions [duplicate]

Possible Duplicate: Intersecting graphics Back in 2009 I posted a question in comp.soft-sys.math.mathematica looking for a function which generates the union of two (not necessarily convex) ...
7
votes
3answers
270 views

Unencoding encoded URLs in a function

Is there a built-in function for decoding encoded URLs in Mathematica? I would like to convert an encoded URL, for example ...
7
votes
4answers
378 views

How to set Block local variables by code?

I need to create a user defined Block function where the Block variables values are defined by code. For example, imagine I have: ...
7
votes
3answers
586 views

Filtering elements from a list

Suppose that I have a list {{{2, 1}, {4, 3}, {2, 4}}, {{2, 1}, {4, 3}, {3, 1}}, {{2, 1}, {2, 4}, {3, 1}}, {{4, 3}, {2, 4}, {1, 2}}} I want to make a new list ...
7
votes
2answers
264 views

What's the purpose of the Unique function?

As the title says: What's the purpose of Unique? I understand that it generates some unique symbol, but when and for what is it to be used? Are there applications ...
7
votes
4answers
291 views

Computing the average over the values of the boxes surrounding a box in a grid

Recenty,I encounter a problem described as below: I have a table that owns many boxes,and each box has a sequence like 1,2,3,4,etc.In addition,every box has a value. Now I want to make the ...
7
votes
3answers
326 views

how to read in a file in the same directory?

Now I am writing a small package. I have written several files and put them in the same directory. And some files need to read in or include another file in the same directory. But when I simply write ...
7
votes
3answers
554 views

Programming Mathematica in plaintext, i.e. no formatting, non-notebook

I'm new to Mathematica and I've just begun reading Paul Wellin's Programming in Mathematica. The book, like many other books and online tutorials, revolves around using the notebook, with all its ...
7
votes
3answers
443 views

Rewriting For loop to FoldList or similar

In CrossValidated, the answer to a question on prediction of number of viewers of Gangnam Style is given in R. I have mapped the answer directly to Mathematica: ...
7
votes
2answers
324 views

find subsequences of constant increase

A list like l = {0, 1, 2, 3, 4, 5, 7, 9, 12, 13, 18, 19} may have subsequences of constant increase, $a_{n+1} = a_n + k$. For example: ...
7
votes
2answers
384 views
7
votes
2answers
1k views

Easier program for period of Fibonacci sequence modulo p

For a little project I need to calculate the period of a Fibonacci sequence modulo p, for which p is a prime number. For example, the Fibonacci sequence modulo 19 would be: $$0, 1, 1, 2, 3, 5, 8, 13, ...
7
votes
2answers
906 views

ParallelTable and Table do not give same result

I have a question regarding the use of Parallelize. In the help one can read that “Parallelize[Table[expr,iter, …]] (which is ...
7
votes
3answers
467 views

Threading a compiled function over multiple arguments of different lengths

I am interested in threading a compiled function over multiple argument lists of different lengths. I will explain this in two steps: Suppose f is some function. Then one can define another ...
7
votes
2answers
215 views

Moving controls from Manipulate to a Palette ( or similar GUI object )

Consider the following snippet as a reference. ...
7
votes
2answers
187 views

Speed up Fourier for Booleans

I'm calculating a bit of the power spectrum of a two color cellular automaton using: ...
7
votes
3answers
394 views

RecurrenceTable not evaluated: mathematica just echoes input

Forgive the newbie question... I am trying to create a table of the following system, following the Stirling example in the documentation, but Mathematica just echoes my input. What am I doing wrong? ...
7
votes
1answer
713 views

Handling failed FindRoot calls

I want to handle FindRoot calls which did not converge (e.g "thrown" error message FindRoot::cvmit) ...
7
votes
1answer
270 views

Find a word's linguistic pronunciation

Is there a way to get a word's linguistic pronunciation given the word as a string? I would like a function LingusticPronunciation such that, for example, ...
7
votes
3answers
454 views

NDSolve and {C, K, Slot} and other built-ins as a variable name

The following problem is an exploration of what causes the error "Input is not an ordinary differential equation" in Mathematica as it seems to have changed from version 8 to version 9. Specifically ...
7
votes
1answer
151 views

The Flat Attribute, Unevaluated and the Evaluation Process

To make this question easy to follow let's give some symbols a couple attributes. Attributes[f] = {Flat}; Attributes[s] = {Orderless}; Now consider the ...
7
votes
3answers
251 views

Restricted accumulation of values

Please consider the following list data. I was trying to accumulate data until the result turns positive the first time and ...
7
votes
1answer
77 views

Aborting from inside a Dialog

Suppose I got in a Dialog and wanted to not Return but Abort the computation. How could I do ...
7
votes
1answer
320 views

Guides for programming CDFs

Are there any tutorials for programming high-quality CDFs, like the interactive calculus textbook presented at wolfram.com? Mathematica's Help is extremely impressive but it really does not help much ...
7
votes
2answers
180 views

Using least independent rectangle area to separate every point

Description I want to add vertical line and horizonal lines between data to make every point have an independent rectangle area. In addtion, every independent rectangle has a number ...
7
votes
1answer
147 views

Raise systemwide keypress event

Is there a way to raise system-wide "keypress" events programmatically from within Mathematica? Say "Ctrl+C" or "Ctrl+V", which all other programs can recognize? This is an attempt to gain simple ...
7
votes
1answer
333 views

How to create a multi-selectable setterbar with colored buttons

Background: consider the following code-snippet. ...
7
votes
1answer
809 views

Efficient backtracking with Mathematica

Backtracking is a general algorithm for finding all (or some) solutions to some computational problem, that incrementally builds candidates to the solutions, and abandons each partial candidate c ...
7
votes
1answer
354 views

Using NETLink.MathKernel.Compute() for graphics results fails with GraphPlot[]

I'm using MMA 8.0 to provide backend on a .NET application I'm writing. I am trying to use the high-level Wolfram.NETLink.MathKernel interface to export an image ...
7
votes
1answer
100 views

Equivalence under common permutations

I have lists which consists of sublists of equal length. The outer list is regarded as a multiset (that is, permutations of the sublists don't matter, but repetitions do), but the order in the ...
7
votes
1answer
396 views

Communication between parallel kernels

Greetings. This is my first post here, also, I am not a seasoned programmer, so any advice pertaining to coding that is not directly related to the problem (stated below) is welcome. I am having ...
7
votes
1answer
299 views

Is it possible to construct a function to make a poor man's Mathematica database?

I have a function that is set up to write to a database with 10-20 standard variables with 10 fields each, but the application is going to a place where database access is not available. Can ...
6
votes
3answers
315 views

Delete elements from a list really fast

I have this bit of code that works, but it's very slow when there are 600k elements in the list: ...
6
votes
2answers
2k views

How to define a differential operator?

I have a linear differential operator, for instance, $L\left (\partial _{t} \right )=\partial _{tt} - 3\partial _{t} + 2$. I use it in 2 different ways: apply the operator to a function: $L\left ...
6
votes
2answers
131 views

How do I access the name of a list in a function?

Background: bar := {1, 1, 1}; foo[var_] := {Hold[var], 2 var} SetAttributes[foo, HoldAll] foo[bar] Result, as expected: ...
6
votes
3answers
298 views

How to eliminate the need to double evaluate a Manipulate so that a Module in its Initialization section works?

Using V 8.04 on windows. I think this issue might be related to the fact that Mathematica reads main body the Manipulate before evaluating or running the Initialization option. Or, might be ...
6
votes
2answers
496 views

Web scraping and multi-threading in Mathematica

I'm working in some web scraping using Mathematica, and today, to speed-up the process, I used bash commands (xargs with parallel options with curl and wget) using ...