11
votes
1answer
213 views

Choosing among different function definitions without sacrificing speed

I'm working on some code that numerically integrates a function, let's call it G, which calls another function, F, that can be ...
10
votes
1answer
375 views

Creating custom notation

How does one generate custom symbols? For example, the physicist notation for the rotation is "nabla cross function". In this case however, Mathematica complains that the ...
16
votes
4answers
732 views

How can I randomly generate a unique, unused symbol?

In a previous question on collecting terms for a multivariable polynomial, I answered with a solution that required a unused symbol to be used for a temporary substitution and back substitution. It ...
16
votes
1answer
517 views

What are the exact guidelines for what is allowed in a CDF?

I have read the guidelines published by Wolfram (these are restricted: non-numeric input fields, dialog windows, and data import and export) but I have a CDF that seems simple enough and seems to ...
15
votes
2answers
192 views

Clearing a specific definition

Consider the case where a symbol has multiple definitions attached to it, a /: Subscript[a,2] := 1 a[b_] := 2 a[b_, c_] := 3 How does one clear (/unset/remove) ...
9
votes
2answers
711 views

How can I get Overlay to position graphics according to coordinates?

If I draw graphics like this, I get exactly what I need: Graphics[{{Blue, Disk[{0, 0}, 10, {0, Pi/2}]}, {Red, Disk[{0, 0}, 3, {0, Pi/4}]}}] But I need to ...
35
votes
3answers
4k views

Best way to give presentations with Mathematica

I have typically used PowerPoint or plain PDFs of slides to give presentations, but with heavy mathematical content, it can be tedious to create these presentations and make them look good. How can I ...
34
votes
4answers
2k views

How can I implement dynamic programming for a function with more than one argument?

Dynamic programming is a technique for avoiding the repeated computation of the same values in a recursive program. Each value computed is immediately stored. If the value is needed again, it is ...
14
votes
2answers
1k views

Texture mapping and resizing a sphere primitive in Mathematica

Background Info In Mathematica, it's only possible to texture map a sphere through the use of SphericalPlot3D or ...
13
votes
7answers
601 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 ...
21
votes
1answer
907 views

How to create regular (planar) graphs?

How to programmatically create and plot regular planar graphs with $k = 3, 4$ or $6$ (not hypercubes) and regular nonplanar graphs of $k = 8$ (see figure)? Note that what matters is the average ...
12
votes
4answers
741 views

Is there a way to Collect[] for more than one symbol?

Oftentimes you find yourself looking for polynomials in multiple variables. Consider the following expression: a(x - y)^3 + b(x - y) + c(x - y) + d as you can ...
25
votes
4answers
578 views

Is it possible to invoke the OEIS from Mathematica?

I had always wondered if there might be a way to write a function, which I'll call OEISData[], that more or less works as a curated data function for The On-Line ...
13
votes
1answer
362 views

ImageAlign doesn't always work correctly

I've been working with ImageAlign in Mathematica 8 and I'm having trouble getting it working reliably. Perhaps there are some subtleties that I'm not yet aware of? ...
76
votes
1answer
3k views

File-backed lists/variables for handling large data

Background Currently I am working with some large data (most of it generated by Mathematica itself). I usually find it a hassle to do this. For example, I just exported a large amount of data to ...
11
votes
1answer
706 views

How to run mathlink external commands in parallel?

I have an external function called increment (for the sake of illustration) that I call from Mathematica using MathLink. I.e., ...
16
votes
2answers
813 views

RegionPlot is producing odd gaps, even for simple functions. Is there an option to prevent this?

When I use RegionPlot to plot the region between two functions, I get strange gaps in the resulting figure. Is there a way to prevent this from happening? For ...
294
votes
12answers
53k views

Where can I find examples of good Mathematica programming practice?

I consider myself a pretty good Mathematica programmer, but I'm always looking out for ways to either improve my way of doing things in Mathematica, or to see if there's something nifty that I haven't ...
37
votes
10answers
2k views

Can Mathematica propose an exact value based on an approximate one?

Sometimes, I use Mathematica to do some hypothesis on homeworks to make the question easier. For instance, when I have to compute big sums when $n\to\infty$ and Mathematica can't give the exact ...
18
votes
3answers
2k views

How to symbolically do matrix “Block Inversion”?

Consider a block (partitioned) matrix matrix = ArrayFlatten[{{a, b}, {c, d}}] where, a, ...
20
votes
2answers
584 views

Is there a way to have Plot draw points on a function where the function is undefined as circles as in textbooks?

A very common feature of graphs of functions used throughout textbooks are simple indications, such as open circles, of the points at which a function is undefined. Is there a way to do this in ...
12
votes
1answer
369 views

Generating a topological space diagram for an n-element set

Over on StackOverflow I asked a similar question for the n=3 case, but the answer given doesn't easily generalize. How can I make a diagram such as this: But for a general n-element space ...
22
votes
3answers
2k views

How can I embed a Manipulate (or other interactive graphics) in my website using CDF?

The new CDF (computable document format) lets you embed a Manipulate or other interactive graphics on your website, and users can play around with your little ...
46
votes
4answers
1k views
30
votes
4answers
663 views

Usage of \[InvisibleApplication] and other related invisible characters

From the front end, \[InvisibleApplication] can be entered as Esc @ Esc, and is an invisible operator for @!. By an unfortunate ...
11
votes
3answers
363 views

Why do buttons with ChoiceDialog freeze the front end?

Pressing the button below will freeze my front end. An unpainted white dialog box comes up, then it completely freezes, and I need to forcibly kill the front end. CPU usage stays at zero during ...
15
votes
3answers
229 views

What is the most convenient way to change options for Graph[] objects?

What is the most convenient way to change options such as VertexLabels in existing Graph objects? (Version 7 users note: ...
58
votes
3answers
1k views

Automatically generating a dependency graph of an arbitrary Mathematica function?

Has anyone written a function to pull the function dependencies of a function? That is, it would be nice to have a function that returns a list of function dependencies as a set of rules, terminating ...
19
votes
2answers
1k views

Efficient way of finding shortest distance between two sets of points in mathematica

I have two sets of 3D points, say a = RandomReal[1, {10, 3}]; b = RandomReal[1, {10, 3}]; I wanna find the first N pairs that have shortest distance between the ...
20
votes
1answer
238 views

How does Return work?

It is not completely clear to me how Return[] works. The documentation says: Return[expr] returns the value expr from a ...
69
votes
7answers
3k views

What are some useful, undocumented Mathematica functions?

There have already been some questions about some undocumented functionality in Mathematica. Such as (please add to these lists!) How can one find undocumented options or option values in ...
20
votes
2answers
691 views

Roughly how many times per day may WolframAlpha[] be used?

The integration of Wolfram|Alpha seems to be one of the (many!) major features of Mathematica 8. Earlier I was reading this Wolfram Blog archive and noticed quite a few articles talking about the use ...
19
votes
2answers
651 views

Data Table Manipulation in Mathematica: Step 2

In this previous post (Data Table Manipulation in Mathematica) we find the brilliant suggestion proposed by Leonid Shifrin that allows to select specific rows identified by the header name. I'm now ...
7
votes
2answers
250 views

automatic coloring of function names

Usually, when I define a function and then use it later, the function name is colored in black. But every once in a while, the function color is blue, both in its definition and when I use it later. ...
55
votes
5answers
3k views

Minimal effort method for integrating C++ functions into Mathematica

As of Mathematica 8, what is the minimal effort way to integrate an existing C++ function into Mathematica? I think we have these: MathLink (it was quite long ago I used it last time) communication ...
35
votes
4answers
2k views

Point Renderings Slightly Off in Mathematica

The Mathematica code ...
26
votes
2answers
513 views

Undocumented form for FilledCurve[]

New in Mathematica 8 is FilledCurve (and its cousin JoinedCurve). The docs state that this function can take a list of segments ...
5
votes
1answer
229 views

How do I find a weighted bipartite graph's minimum edge cover using Mathematica 8?

In graph theory, we use the Hungarian Algorithm to compute a weighted bipartite graph's minimum edge cover (a set of edges that is incident to every vertices, the one with the minimum total weight.) ...
21
votes
2answers
560 views

How does Plot work?

I considered the following function: sin[x_] := Module[{}, Print["x=", x]; Sin[x] ] in Mathematica. Next, I tried to plot it using: ...
4
votes
2answers
202 views

Better use of Mathematica's PolynomialReduce[]?

I've been using scPhiDecomp[expr_]:= PolynomialReduce[expr, {x^2-y^2,2 x y}, {x,y}] which works great on ...
86
votes
5answers
3k views

How can one find undocumented options or option values in Mathematica?

Mathematica has a lot of undocumented or poorly documented options. How does one go about working out if there is an undocumented option that might solve a particular problem? How does one work out ...
18
votes
2answers
613 views

How safe is Encode?

How safe is an encoded package (using locked, etc)? If I don't specify a personal key, I understand that the encoding key must be somewhere in the Mathematica program itself, and so it is not a ...
39
votes
0answers
806 views

Numbered equations/formulas

How do you number equations in Mathematica notebooks so that they are exported correctly into latex? In case you don't know how to put numbered equations here is quick review. Open a new notebook ...
33
votes
3answers
663 views

Replace inside Held expression

I wish to make functional replacement inside Held expression like this: ...
39
votes
4answers
3k views

Creating Mathematica packages

I'm building a package to help me write packages and their documentation. In this post I explained how to make a package and its documentation. In the answer I provided I describe how to build a very ...
44
votes
2answers
1k views

What are the best practices / most common / idiomatic ways to report errors in Mathematica?

In particular, what are the best ways to report errors about incorrect arguments to a function? Checking for the correct arguments is relatively easy using patterns, but how to report an informative ...
17
votes
2answers
235 views

Symbolic derivatives are being calculated numerically

Just found the following while debugging a problem. Mathematica is calculating the derivative of IntegerPart[x] in some odd way: ...
30
votes
3answers
663 views

Is there a Mathematica API for the functions.wolfram site?

Is there a Mathematica API for the functions.wolfram site? If there's not, has anyone implemented a web scraper for it? For example it would be nice to be able to access ...
85
votes
3answers
11k views

Alternatives to procedural loops and iterating over lists in Mathematica

While there are some cases where a For loop might be reasonable, it's a general mantra – one I subscribe to myself – that "if you are using a ...
38
votes
3answers
737 views

The clearest way to represent Mathematica's evaluation sequence

WReach has presented here a nice way to represent the Mathematica's evaluation sequence using OpenerView. It is much more clear way to go than using the standard ...

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