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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4
votes
1answer
99 views

How to check the option value?

Given that I have a function func as follow: To check the value of options, I using the step-by-step method If[] ...
4
votes
1answer
64 views

How to define an expression which is differently evaluated in calculations and printed

Let's say, we have a list: values = {1.2, 0.04, 0.9}; Is it possible to replace 0.04 by some expression, which displays as ...
0
votes
0answers
55 views

How to spend any image in “2D” or “3D” to an image mesh, ie as a wire frame in black and white?

How to spend any image in "2D" or "3D" to an image mesh, ie as a wire frame in black and white? For example some of these: edit :example output
9
votes
1answer
98 views

How to implement a custom random process object?

I want to implement a custom random process thing1 to pass to RandomFunction. The process I have in mind is conceptually extremely simple: two alternating Poisson ...
1
vote
0answers
57 views

Should I Remove the initial symbols of Module?

Often we use Module to construct complicate function. Consider that Module create new vars every time we run the function, should I remove the initial values at the end of Module-function?Or should I ...
0
votes
0answers
72 views

Fun/Frustration With Coding Coding Theory

I have code following from this post: http://math.stackexchange.com/questions/1317722/fun-frustration-with-coding-coding-theory I think I am done with the code, but now I face a single problem. The ...
2
votes
1answer
145 views

How to determine whether an expression can act as a “good” function?

It's not easy to see whether an expression can act as a "good" function. A good function refers to an operater that transforms symbolic entities like 1+x^2 or ...
1
vote
0answers
60 views

Arrange order of evaluations (please help these unit vectors)

I need help to control order of evaluations. Here I try to use Manipulate to control n unit vectors. Their positions are initially random but head left. The 2 operations are 1) translation: moving ...
5
votes
0answers
42 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
138 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 ...
0
votes
1answer
79 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: ...
9
votes
0answers
87 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
42 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
55 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 ...
3
votes
1answer
84 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 ...
13
votes
2answers
342 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?
0
votes
0answers
13 views

Number of pairs (a, b) such that a*b < N where a, b, N are integers greater than 0 [migrated]

I have this code in C to calculate number of such pairs:: ...
5
votes
0answers
180 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
53 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
114 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
50 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
139 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 ...
2
votes
3answers
101 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];); ...
3
votes
1answer
160 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 ...
2
votes
2answers
144 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 ...
10
votes
2answers
214 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, ...
0
votes
0answers
47 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 ...
5
votes
1answer
281 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
76 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 ...
2
votes
2answers
93 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 ...
1
vote
0answers
75 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) ...
1
vote
1answer
47 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
38 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 ...
1
vote
1answer
51 views
1
vote
2answers
92 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
70 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.
0
votes
0answers
33 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
63 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
69 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
113 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
81 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 ...
1
vote
1answer
104 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
323 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: ...
-1
votes
1answer
115 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
85 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
69 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
162 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 ...
5
votes
4answers
311 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 ...
0
votes
2answers
197 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
84 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 ...