9
votes
3answers
3k views

General::ivar is not a valid variable when plotting - what actually causes this and how to avoid it?

I was just evaluating a couple of expressions and started to get errors like this: ...
43
votes
8answers
2k views

Updating Wagon's FindAllCrossings2D[] function

Stan Wagon's Mathematica in Action (second edition; I haven't read the third edition and I'm hoping to eventually see it), demonstrates a nifty function called ...
18
votes
3answers
909 views

Using pure functions in Table

I need a table with the elements made of pure functions and list elements. This is a simplified example: I need a list as: ...
35
votes
7answers
2k views

Character edge finding

The following line of code finds the edge of a character: ...
26
votes
3answers
5k views

ShowLegend values

How do I get ShowLegend to put the max and min values that a plot produces. for example, when using ListDensityPlot, with ...
37
votes
7answers
4k views

Intersecting graphics

Does the Mathematica graphics system have any concept of intersecting graphics? I've not found much in the documents so far. For example, if I want to show the intersection of two shapes: ...
24
votes
2answers
1k views

Do I have to code each case of this Grid full of plots separately?

I have written some custom functions to draw multi-panel graphs like this one: It's done by passing a matrix of (custom) plotting functions to a MultiPanelGraph ...
17
votes
1answer
5k views
17
votes
5answers
884 views

How to perform a depth-first preorder traversal of an expression?

Due to confusion of terminology on my part I asked the wrong question before. Since it has already received other answers I shall not edit it, but instead ask the question I meant to in the first ...
23
votes
1answer
443 views

Why doesn't PatternTest work with Composition?

While playing around with the solutions to this question, I've found some very strange behaviour: ...
73
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 ...
78
votes
1answer
3k views

Programmatic formatting for Mathematica code - possible?

It seems to be both an interesting programming challenge and a very useful practical application to have a Mathematica program which would allow one to pretty-print Mathematica code, so that it is ...
59
votes
2answers
2k views

Flatten command: matrix as second argument

One thing I could never wrap my head around is how Flatten works when provided with a matrix as the second argument, and the Mathematica help isn't particularly ...
55
votes
7answers
2k views

Functional style using lazy lists?

Let's say I want to answer the question "what are the first 400 palindromic prime numbers?" The first approach that comes to my mind from the set of languages that I know is to use some sort of lazy ...
37
votes
3answers
815 views

Replace inside Held expression

I wish to make functional replacement inside Held expression like this: ...
47
votes
2answers
9k views

How can I use Mathematica's graph functions to cheat at Boggle?

Boggle is a word game played with 16 dice and a 4x4 tray. This question is inspired by a Stack Overflow question about Boggle that I decided to solve using Mathematica. In addition to Mathematica, I ...
24
votes
5answers
10k views

How do I clear all user defined symbols?

Is there some way to do this other than going to Evaluation -> Quit kernel and firing a new one up?
31
votes
1answer
957 views

Transferring a large amount of data in parallel calculations

This question is inspired by one of @whuber's answers Consider the following code: ...
35
votes
2answers
4k views

What is so special about Prime?

When we try to evaluate Prime on big numbers (e.g. 10^13) we encounter the following issue : ...
17
votes
2answers
799 views

Using a list of tuples in a pure function

I want to use a list of tuples within a function to make assignments. Say I want to make assignments of the form value[i,j] = val What I have is a list of ...
13
votes
5answers
689 views

How are parameters evaluated for a Plot in Manipulate

I am trying to get my head around how Manipulate evaluates functions in a Plot. I have read the introduction to Manipulate, and introduction to Dynamic, but I still ...
11
votes
4answers
2k views

How to modify function argument?

Usually in programming languages, function arguments are normal local variables, which can be modified. Is this not true in Mathematica? ...
17
votes
6answers
1k views

Annoying display truncation of numerical results

I have a lot of data to inspect. An example of a number in my program is 123.189094 This gets displayed as 123.189 ...
12
votes
7answers
527 views
55
votes
1answer
2k views

Open-source IntelliJIDEA plugin to support Mathematica development

Although we already had a question asking for development alternatives to Wolfram Workbench, I want to ask a more specific question: One of the most advanced IDE's especially for Java programming ...
41
votes
7answers
1k views

How to “Copy as Unicode” from a Notebook?

I spent some time manually editing a post replacing Mathematica ASCII \[Alpha] with Unicode α. I did this by laboriously ...
35
votes
4answers
841 views

How to avoid nested With[]?

With[ {v1 = #}, With[ {v2 = f[v1]}, g[v1, v2] ] ] How to avoid nested With[] like the above? I'd like to use ...
31
votes
2answers
2k views

Is it possible to change the colors of the highlighted code in the Mathematica frontend?

With Format -> Edit Stylesheet... it is possible to adjust text-properties, text-colors, formatting of equations, etc of a notebook and to use this style-definitions again by installing it as ...
11
votes
3answers
995 views

Elegant manipulation of the variables list

I have a list of global variables (some of them are indexed variables), for example: varsH = Hold[U0[1], U0[2], B0, V0[1], V0[2]] Or (if it is easier to handle) ...
26
votes
4answers
1k views

Can I simplify an expression into form which uses my own definitions?

This seems like a simple thing to do, but I couldn't find anything relevant from Mathematica documentation. So suppose I have an expression: a*b/(a + a*Cos[a/b]) ...
17
votes
2answers
2k views

How to fit 3 data sets to a model of 4 differential equations?

I'm a biologist and a newbie in Mathematica. I want to fit three data sets to a model consisting of four differential equations and 10 parameters. I want to find the parameters best fitting to my ...
11
votes
2answers
5k views

How to specify assumptions before evaluation?

If I request mathematica evaluate an integral for me, I'll often get a more general ConditionalExpression than I want. Example : ...
46
votes
6answers
2k views

Functions vs. patterns

Every time I define a new function, I wonder which construct I should use: true functions obtained by using Function, or rule-based syntax. For example, these are ...
43
votes
4answers
9k views

How to find all the local minima/maxima in a range

I want to find : all local maxima in range all local minima in range From those points I can interpolate and combine functions upper and lower boundary. What I am really interested in, is the ...
35
votes
3answers
4k views

Plotting implicitly-defined space curves

It is known that space curves can either be defined parametrically, $$\begin{align*}x&=f(t)\\y&=g(t)\\z&=h(t)\end{align*}$$ or as the intersection of two surfaces, ...
33
votes
3answers
2k views

Saving Mathematica kernel state?

If I save a notebook, I only save what I see. That is, if I close Mathematica and reopen the notebook later, all previous calculations are lost, except for those things I've output. Now I know that ...
28
votes
3answers
5k views

ListPlot with each point a different color and a legend bar

I would like to generate a ListPlot with the color for each point in the plot corresponding to a particular value (not associated with the position in the plot). I'd then like to add a legend ...
28
votes
2answers
1k views

Automating Esc [[ Esc formatting?

Is it possible to program the Front End to automatically format double square brackets without having to type Esc[[Esc each time? It's awful to have to type Esc ...
42
votes
2answers
1k views

Head and everything except Head?

I have been working on picking expressions apart using Head and Part and encountered a little mystery. Consider the canonical ...
24
votes
1answer
969 views

Customizing syntax highlighting for private cell styles

Is there any way to set up a cell style with a particular syntax highlighting? For example, I'd like to have a CProgram cell to write in blue the C special words. I have done it by setting ...
6
votes
3answers
2k views

Assigning values to a list of variable names

As part of a calculation I need to do something like this Evaluate[{aaa, bbb, ccc}[[ index]]] = {1, 2, 3, 4, 5} so if index is ...
41
votes
2answers
2k views

Internal`Bag inside Compile

Since Internal`Bag, Internal`StuffBag and Internal`BagPart can be compiled down, it is a ...
44
votes
2answers
2k views

Once more on object orientation in Mathematica: does it have to be so hard?

Recently I came across a set of problems which would be solved most easily within an object-oriented approach. I first attempted to solve them by other means, but found the complexity of the code ...
32
votes
7answers
13k views

Labeling individual curves in Mathematica

I need to create a plot for export and inclusion in a report. Is there a better way to label curves than PlotLegends? From what I've read and my personal ...
35
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 ...
34
votes
5answers
3k views

Filling a polygon with a pattern of insets

I am trying to fill a shape with diagonal lines. I am aware of Texture, but it rasterizes the fill pattern, which is not desirable. Here was my crack at it: ...
34
votes
5answers
1k views

How to abort on any message generated?

Mathematica is a bit unusual as a programming language because it never stops on messages, regardless of whether the message is an error, a warning or just an informative message. It simply prints the ...
27
votes
5answers
2k views

How to efficiently find positions of duplicates?

Is there an efficient way to find the positions of the duplicates in a list? I would like the positions grouped according to duplicated elements. For instance, given ...
32
votes
3answers
2k views

Antialiasing in 3D

Is it possible? Is it platform specific? Does it rely on the graphics hardware? Why does the antialiasing slider under Preferences > Appearance > Graphics do nothing? I remember seeing some ...
23
votes
7answers
3k views

How to avoid returning a Null if there is no “else” condition in an If contruct

I need to use If but with only one option that is if "a" then do "b", else do nothing. So I wrote If[a,b] but the problem is ...

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