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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5
votes
0answers
51 views

How is CellContext->CellGroup supposed to work?

After reading the documentation on the subject, I still cannot get CellContext->CellGroup to work. Here's a simple example. (Unfortunately, I cannot easily ...
4
votes
1answer
158 views

Can I do constraint programming in Mathematica? [closed]

I would like to know if there is a way to do constraint programming in Mathematica? I think there are no built-in functions, but maybe some of you know some additional packages addressed to the ...
1
vote
1answer
87 views

Functions behaving weirdly

The following code f[k_, n_] := Sum[2*(1 + Sum[f[k - j, n - m - j], {j, 1, k - 1}]), {m, 1, n - k + 1}] f[4, 7] f[4, n] gives the output: ...
10
votes
0answers
153 views

Confused by the opts : OptionsPattern[ ] pattern

I'm trying to make sense of the syntax in the clause opts:OptionsPattern[], as found in this standard "rule-based" (pseudo-)function definition pattern: ...
1
vote
1answer
49 views

Why this isn't a valid argument? [duplicate]

I am having truble understanding why F1 produces an error, since both time and velocity are the same kind of object: ...
0
votes
1answer
71 views

Mathematica Code Involving For Loops Not Completing All Iterations [closed]

First of all, thank you for taking the time to read this. I'm working on a portion of code related to the genetic algorithm that is not producing the expected results. What the code is supposed to do ...
5
votes
1answer
162 views

Is it possible to update Dynamic objects even when they are off screen?

I am using Dynamic and DynamicModule to display graphics/statistics generated from a long-running set of parallel tasks. The ...
14
votes
2answers
385 views

How to programmatically ask if Mathematica is running as an Administrator

To avoid execution problems in a program I need to know if Mathematica has been "Run as administrator". What would be the cleanest way to programmatically getting this information?
6
votes
0answers
582 views

How to create protected single-file stand-alone CDF applications

After hours of work trying to understand how much protection I can get when creating stand-alone CDF applications I have come to the decision that the best protection to my work is provided by ...
0
votes
1answer
107 views

How to count column occurrences in a matrix?

I have a matrix of data, and I want to count the number of columns that match, and have some way to organize them by frequency. But I don't want to count the entire column, but consider the matrix ...
5
votes
1answer
322 views

Reap, Sow with Parallelize: bad performance, why?

I have a question about the performance of Reap and Sow with Parallelize. I am aware of the following questions How to collect result continuously (interruptible calculation) when running parallel ...
1
vote
1answer
60 views

Emulating Case Pattern replacement

As most regular users, I have developed utility functions complementing the Wolfram language for frequent tasks. In particular, I have variations on Cases (see ...
1
vote
1answer
204 views

Transform linear system into a matrix form

I have a system of linear equations in variables $A_n$ of form: $$ \sum _{k=-K}^K h_k A_{n-k} J_{n-k}\left(\frac{(1-i) \text{$\eta $Sqrt}(n-k)}{\sqrt{2}}\right)+A_n\left(\frac{(1-i) \eta \sqrt{n-...
2
votes
2answers
142 views

Problem with the output of a function I program

(This is the function that I programmed) Zm2[Z_, nk_] := (zm2 = 0; For[i = 0, i < Length[Z], i++, zm2 += nk[[i]] *Z[[i]]* Z[[i]];]; Return[zm2];); (...
4
votes
1answer
193 views

How to further accelerate arithmetic with Fermat Pseudoprime and Fibonacci number

I've been working on this all night, and I have made this go pretty fast, compared to my first iteration of the program, but now I'm out of ideas. I'm trying to write a program to test (by good ...
3
votes
2answers
274 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 ...
11
votes
2answers
287 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
0answers
101 views

Calling a custom function in slave kernel process connected through mathlink [closed]

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 "...
5
votes
1answer
343 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 ...
0
votes
1answer
87 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 ...
5
votes
2answers
236 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 ...
2
votes
0answers
180 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) ...
2
votes
1answer
89 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 ...
0
votes
0answers
117 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 ...
2
votes
1answer
87 views
1
vote
2answers
116 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 ...
2
votes
1answer
97 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.
1
vote
1answer
245 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. ...
6
votes
1answer
93 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 ...
1
vote
1answer
234 views

Fibonacci Line Search Method

I am attempting to write a code to find to bracket the minimum of a function using the Fibonacci Line Search Method, I believe my code is well written but I am not ...
0
votes
1answer
239 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 ...
2
votes
1answer
183 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 ...
3
votes
2answers
357 views

How to force Return[] to return from an arbitrary point (like in C++)?

I need to test some complicated conditions to calculate a Return value. But MMa doesn't let you Return[] from anywhere the way C++ does. The structure of my Module is similar to this: ...
0
votes
1answer
298 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 ...
-1
votes
1answer
148 views

Trying to write my own Greedy/ Nearest Neighbor Algorithm

So I'm trying to write my own function and compare it to the results I have from using FindShortestTour. Does anyone know how to find the distance from each city to each of the others without ...
2
votes
1answer
85 views

Block works when directly used but not when used in a function

I want to calculate a derivative such as: $\delta f=\sum_{i=A,B} \sum_{k=1,2,3} \frac{\partial f}{\partial a_k^i}$. Since $ a_k^i$ are assigned values other places in the code, I have used ...
3
votes
1answer
174 views

How do I create an array by applying a function to the index of each element?

I am looking for something like matrix(m, n, f), but for Mathematica rather than MuPAD, and for arrays rather than matrices. That is, I'm looking for a(n efficient)...
5
votes
4answers
652 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
vote
2answers
550 views

FindShortestTour to solve Traveling Salesman Problem

I'm trying to write my own code to find the shortest route but I'm lost on how or where to start. Does anyone have any idea how the FindShortestTour function works? What type of algorithm or structure ...
0
votes
1answer
199 views

Eigen energies of 2D time independent Schrödinger equation

Firstly, I am aware that a similar question of this type was asked, but it was not helpful as it was only one dimensional (so please don't mark my question as a duplicate) The trouble I am having is ...
0
votes
3answers
98 views

Diophantine and odd

need to resolve this Diophantine equation, but with the condition that a, b, c belong to the set of odd numbers from 1-51, as I write this condition in the code ...
7
votes
1answer
320 views

How is LHS = RHS; … ; LHS (nontrivially) different from … ; RHS

I'm trying to understand how Mathematica thinks about the results of Set. Suppose we perform LHS = RHS. I'm focusing on when ...
8
votes
2answers
251 views

How to define the Bernstein function like the built-in BernsteinBasis?

We know the Bernstein function defined as below: $$B_{n,i}(u)=\binom n i u^i(1-u)^{n-i}$$ And we define $B_{n,i}(u)=0$ when $i<0 $ or $i>n$ In addition, the first derivative of $B_{n,i}(u)$ ...
9
votes
3answers
290 views

How to speed up auxilary DoolittleDecomposite function?

The Doolittle Decomposition algorithm as below: $$A=LU$$ where $A= \begin{pmatrix} a_{11} & a_{12} & \cdots a_{1n}\\ a_{21} & a_{22} & \cdots a_{2n}\\ \vdots & \vdots & \vdots ...
0
votes
0answers
41 views

$MessageList inside and outside Block[]

Why does 1/0 $MessageList return ComplexInfinity whereas ...
0
votes
1answer
38 views

How to combine two or more groups while selecting form the unbalanced panel data if the number of obs is less than a scalar in certain groups

I have an unbalanced panel data. I want to calculate group statistics for each group. However, if ith group has less than K obs, then I want to combine ith and (i+1)th groups to calculate group ...
2
votes
0answers
89 views

How to use RunProcess to run python interpreter

In a related question How to use RunProcess to import external function? @taliesin provides a very nice answer illustrating using RunProcess to launch a GO http server. Has anyone, or does anyone ...
2
votes
1answer
63 views

Evaluate recursive funtion as a whole before computing a recursive step

I'll try to make a basic example of my problem with $n$ being an array of elements, ex. $\{1,2,2,3,3,3\}$: If i have a sum which needs a computed value i would like to compute it beforehand and store ...
9
votes
2answers
301 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 (...
4
votes
1answer
98 views

subtleties about variable shadowing in Block[]

Let' s consider this packege : BeginPackage["myProgram`"]; myProgramF::usage = "arg + 1"; Begin["`Private`"]; myProgramF[arg_: 0] := arg + 1; End[]; EndPackage[]; ...