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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227
votes
23answers
29k views

What are the most common pitfalls awaiting new users?

As you may already know, Mathematica is a wonderful piece of software. However, it has a few characteristics that tend to confuse new (and sometimes not-so-new) users. That can be clearly seen from ...
0
votes
0answers
21 views

All irreducible factors of a polynomial over $F_{p[x]}$

I am new to Mathematica. Can anyone explain me how to write a program that inputs two integers $n$ and $p$, where $p$ is prime, then returns all irreducible factors of the ...
0
votes
1answer
71 views

Recursive Euclidean algorithm in Mathematica

Can anyone explain to me how do I use a recursion, if I don't know the limit. For example, I need the remainder r of the Euclidean algorithm for gcd(a,b) which equals 0. I figured out that the ...
4
votes
0answers
123 views

Delete duplicates by a criterion

The description This question came from my recent work. I achieved four groups points by data processing and then visualized them with Mathematica (shown as below) And I know that ...
5
votes
1answer
145 views

Force Dispatch to generate dispatch tables

Dispatch creates hash tables only for lists of length larger than 3. Is there any way to force MMA to create hash tables even for lists of length smaller than 4? ...
6
votes
0answers
261 views

How to restrict the mouse cursor to stay within a box?

I'm trying to use Mathematica to write small games, and I find that it would help to restrict the player's mouse into the game window (just like other games do). Is there any way to achieve this? ...
16
votes
0answers
211 views

Can code optimize code?

Are there functions, programs or packages that deal with optimizing mathematica code i.e. re-writing ineffecive or convoluted code. -This question has haunted me since I joined SE. The background for ...
1
vote
1answer
75 views

Multiply out product of sums

For a specific quantum mechanical problem I need to multiply out operators in order to calculate a trace by hand. For example I need a Hamiltonian squared with $H^2$. The Hamiltonian contains of a few ...
9
votes
2answers
192 views

Built-in symbols that support operator form

In version 10 some built-in symbols are updated to support operator form like the Derivative. For example, Select, ...
1
vote
1answer
44 views

Is it possible to use FormObjects and FormFunction in a stand-alone notebook?

I have been looking at the FormObject and FormFunction. Can FormObject and ...
49
votes
1answer
1k views

Is this 30% slowdown in Mathematica 10 due to DownValues lookup time?

Running several numerical self-programmed packages I realized already some time ago that Mathematica 10 needed between 20 and 40% more time. I did already report this of course with a simple example ...
1
vote
1answer
67 views

Can I use Switch with an inequality? [closed]

I'd like to have something like: Switch[x, 10, a = 3; b = 7, >10, a = 5; c = 6, _, a = 7; d = 12, b = 1]; I can't seem to get this to work.
22
votes
0answers
359 views

What Mathematica features and idioms have $n^2$ complexity or worse

Here are a few: AppendTo[data, elem], Sort[data, test], in some cases use of ___ (as ...
28
votes
8answers
2k views

Can this be written well, without loops?

Inspired by this question I would like to know if the following code can be written without explicit loops (For, While, etc.) in a clean, efficient and non-contrived way. I have been unable to do so. ...
346
votes
13answers
72k 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 ...
52
votes
3answers
1k views

Reconstruct text pages cut by shredder

Q1: I have a page of a printed text file, but it was cut by a paper shredder (from top to bottom). You can download all the paper fragments here. Here are some of them. How can I reconstruct it? ...
56
votes
11answers
11k views

How to check if a 2D point is in a polygon?

Background: I use code from An Efficient Test For A Point To Be In A Convex Polygon Wolfram Demonstration to check if a point ( mouse pointer ) is in a ( convex ) polygon. Clearly this code fails for ...
18
votes
2answers
520 views

Most influential and/or disrupting features introduced with new versions of Mathematica

This is something that has been bugging me for ages. With every upgrade, Mathematica has added new functionalities and amended some of its bugs. In the process, though, some older functionality has ...
5
votes
1answer
268 views

Only `Break` from innermost loop

How could I Break from only the innermost loop in a Do[stuff,{i1,i1min,i1max},{i2,i2min,i2max},...] ? I get the desired ...
6
votes
2answers
301 views

Association and rudimentary object-oriented programming

Doesn't Association provide us rudimentary object oriented programming via constructs like ...
45
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 ...
0
votes
0answers
32 views

Calling a custom function in slave kernel process connected through mathlink

I am performing a small experiment to check if we can call/execute a custom package function in slave kernel launched from master using mathLink. I have created a dummy application called ...
2
votes
1answer
129 views

How can I invoke the solution of NDSolve to determine a parameter in my equation just inside NDSlove?

I am trying to solve a differential equation by NDSlove for $h(x,t)$. It reads $$h_t=h_{xx}-V_h-\lambda(t)$$ where $V_h$ is a given function of $h(x,t)$ denoted by ...
0
votes
1answer
71 views

`Do` structures - listing iterated values

Please excuse the crudity / simplicity of this question, hbut I have never really got on too well with Do structures - perhaps I don't use them enough - perhaps I ...
6
votes
2answers
350 views

Implement the Bisection algorithm elegantly and easily

Description: Rencently, I have finished my course Numerical Analysis, so I'd like to implement many algorithm that I have learned from that course.By this practice, I hope that I can improve my ...
2
votes
2answers
79 views

Creating a Cayley's table of square

I'm interested in creating a Cayley's table of square using Mathematica. I'm not a programmer but occasionally resort to using Mathematica to simplify my work insofar as the programming doesn't take ...
13
votes
3answers
361 views

Notebook vs. DocumentNotebook; display a Notebook inline, like a DocumentNotebook

If you evaluate a DocumentNotebook[] expression in the front-end, it nicely displays inline, inside of an output cell in the current notebook: For my purposes, ...
1
vote
0answers
42 views

How can I launch kernels in series using mathlink

I have written below code to launch n kernels connected to one another in series using mathlinks. Before you read the code allow me to be more precise what i want to achieve: Source kernel(k1) ...
50
votes
7answers
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 ...
8
votes
2answers
171 views

Relaxation of Mass-Spring System with Pinned Masses

Problem Assume that four masses are connected to each other by springs while two of them are pinned down at their initial positions. Find the position of masses when system is at its minimum ...
24
votes
6answers
1k views

How to understand the usage of Inner and Outer figuratively?

Description: In Mathematica the functions like Thread, Inner, Outer etc. are very important ...
5
votes
3answers
254 views

Split list of states by run lengths and discontinuous changes in state

I was asked to look into writing some simulation code for a user, where the simulation output (x) would oscillate between three possible states: ...
0
votes
0answers
20 views

Solving (one variable) Linear Equation by Dividing Slope by Constants Accumulation? [migrated]

I've been Google searching for this, and apparently my Googlefu is not strong today, or I'm doing something wrong. I have been told that it is possible to solve a one variable linear equation by first ...
9
votes
4answers
320 views

Interactively inspecting parts of an object

There have been times when I want to find the structure of an object in order to extract some part of it. For example, extracting the x and y coordinates from a Graphics object generated by Plot. I ...
0
votes
0answers
30 views

Evaluate notebook using text-based interface

I am trying to evaluate a notebook using a text based interface so that it can be submitted to a computing cluster. I have seen this stackexchange page and attempted to use ...
6
votes
5answers
445 views

How to compile the code for generate Pythagorean_triple?

I am finding Pythagorean_triple, it worked slowly. I tried to compile, but it gives some warnings. I also use "Case" or "Do" ,both of them failed.I'm sure my CCompiler has been set correctly. How can ...
1
vote
2answers
91 views

How to find total distance covered when I have a list of GeoPositions?

So I have a list of GeoPositions and I need to find the distance covered in that order? I know I can find the distance from each city and then add them all up but I was wondering if there is any ...
0
votes
0answers
30 views

Debug package with command line arguments

I'm creating a package that takes as arguments input from the command line using $ScriptCommandLine. What's unclear to me is how to best debug this package. How do others perform these tasks? I ...
0
votes
1answer
52 views

How to properly use conditionals inside NDSolve

Currently I am working with Mathematica to learn the program, and I'm confused what exactly is wrong with this code. ...
24
votes
4answers
4k views

K-means clustering

In MATLAB, there is a command kmeans() that divides an array into $k$ clusters and calculates the centroid of each cluster. Is there any command in Mathematica to ...
4
votes
4answers
275 views

Spiral roots, how?

I found this picture on the net, as I can play in mathematica
2
votes
2answers
159 views

Issue with Set function

Tables often come with column headers. Indexing the columns with the header is a natural thing to do. Although a proper dictionary is the usual solution in such a case, I find it often practical and ...
59
votes
2answers
10k views

Is there an open source implementation of Mathematica-the-language?

I've seen questions before such as "What is the best open-source equivalent for Mathematica?", but that specific question (and that line of inquiry in general) cares more about the computer algebra ...
6
votes
1answer
66 views

Completion in terminal?

I know that it is possible to run Mathematica in Terminal. But I didn't find a way to get completion work in Terminal. I mean completion by ...
54
votes
3answers
4k views

Metaprogramming in Mathematica

Being functional, and having no "quotation", i.e. essentially treating data and programs semantically same, Mathematica seems naturally capable of doing metaprogramming. But could anyone construct a ...
0
votes
1answer
73 views

How do I find the nearest city out of a list of cities?

I am trying to find the next closest city to city 1 and want to use a certain radius to check what is the closest city I'm trying to create an algorithm for a TSP. Does anyone know how to implement ...
4
votes
2answers
289 views

Approximate value for the area between the curve

I've got this task: Use Mathematica to obtain an approximate value for the area between the curve $y=1/4$ and the x-axis over the interval $[1,2]$ with $50$ subintervals using the left ...
5
votes
4answers
276 views

Efficient way to sum all the primes below $N$ million in Mathematica

Today, I saw a problem described as below: Sum all primes below $N$ million At the beginning, I feel it is rather simple to calculate it in Mathematica ...
-1
votes
1answer
102 views

Implementing the Golden Section Rule

I am attempting to write a code which brackets the minimum of a unimodal function, using the Golden Section Method Below. I am have serious issues debugging my program though, any help will be ...