Linked Questions

0
votes
1answer
577 views

Assigning value to an array in nested for loop [duplicate]

I want to write a code like X={}; index=1; max=3; For[i=1,i<=2,i++, For[j=1,j<=2,j++, X[[index]]=i*j; index++ ] ] But I am not getting ...
0
votes
1answer
46 views

An elementary question about For loop [duplicate]

Assume we have this For loop: For[i=1,i<10,i++, i^2]. How can we put the squared values ...
472
votes
37answers
107k 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 ...
187
votes
3answers
42k 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 ...
40
votes
8answers
3k 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. ...
58
votes
5answers
6k views

Are there any cases when For[] loops are reasonable?

To my mind the only reason for the existence of For[] loops in Mathematica is to allow new users with some experience in procedural programming languages to write ...
7
votes
8answers
540 views

Finding C[i]'s expression in DSolve solution

An example, the command DSolve[y''[x] - 4 y[x] == 1, y[x], x] gives solution ...
9
votes
2answers
676 views

Optimizing Mathematica Code

I have implemented the whole Baum-Welch Algorithm for training Hidden Markov Models as described in Rabiner's paper Here is my code that calculates the Forward Probabilities` ...
5
votes
3answers
1k views

How to speed up a process

I am wondering how to speed up the following code: Currently it takes more than two sec to be processed. ...
6
votes
1answer
529 views

An efficient way to translate a triple for-loop from Matlab to Mathematica

This is my first post on StackExchange, so if I violate any etiquettes, I apologize in advance. I am a senior engineering student who has been using Mathematica for a year now. For one of my classes, ...
5
votes
7answers
340 views

Computing only Prime Powers with NestList

Is there a simple way to compute only prime powers of a function f with NestList? That is, I want to compute: {f[x_0], f^2[x_0]=f[f[x_0]], f^3[x_0], f^5[x_0]...} ...
3
votes
2answers
1k views

For Loop and Sum

I am requested to do a sum of the first fifty positive even numbers by using For loop. The For loop that I created is ...
7
votes
2answers
504 views

CUDA image processing

I am having an issue with image processing involving CUDALink. ...
13
votes
1answer
644 views

Pascal records and Mathematica programming

Background: "experienced" Pascal-programmer (DOS-era, never got into OOP) proud owner of Mathematica ver 11.2 have used Mathematica for years to do my share of number crunching and plotting to ...
5
votes
2answers
563 views

Runge-Kutta implemented on Mathematica

I am trying to solve differential equations numerically, so I am trying to write a 4th -order Runge-Kutta program for Mathematica (I know NDSolve does this, but I ...
9
votes
2answers
277 views

Is there a way to create ZIP OutputStream ?

I want to write data to a file using compression. Is it possible to do that just in time (like in java ZipOutputStream). E.g. what I want: ...
12
votes
1answer
681 views

Why does NDSolve fail to solve the PDEs and spit out mconly warning?

I try to solve two coupled PDEs with NDSolve using the following code: Set two operators: ...
6
votes
3answers
359 views

How do I modify a symmetric matrix while maintaining symmetry?

I'm trying to figure out how to create a For loop for a symmetric matrix. I have a 5 $ \times $ 5 symmetric matrix consisting of 1's and 0's and I'm trying to ...
8
votes
2answers
205 views

Converting a backward/forward sweep code for optimal control to _Mathematica_

I'm trying to convert to Mathematica a simple backward/forward sweep (with RK4 integrator) code to solve an optimal control problem in epidemiology, but I'm getting some error messages and I cannot ...
3
votes
1answer
2k views

Selecting elements from a list of lists [closed]

Being a novice, I'm having trouble with the following: I have a list of lists and want only those elements where the second element of the second level is positive. So, for example, from ...
3
votes
7answers
240 views

How can i change some numbers in a list?

I do not want to change all of them just some of them in particular rule. For example the list is given a={1,2,3,4,5,6,7,8,9....,100} If the number is bigger than ...
2
votes
2answers
698 views

For/ Do loop on a lists of two variables

I am trying to get an output of the following kind Out = Do[Evaluate[f[x,y]],{x,table1},{y,table2}] Here Out is a N-times-1 dimensional array/list and N is the ...
5
votes
1answer
428 views

Random walk in one dimension β€” meeting of two particles

I'm new to Mathematica and still teaching all by myself, hope you bear with me. I have the code: ...
3
votes
3answers
200 views

For Loop to Sum numbers in a list

I'm asked to create a For[] loop that will sum positive numbers in a list. I am unsure of how to do this. ...
4
votes
3answers
452 views

Dot products and For-loops

I'm taking a class where we're working with matrix applications inside of Mathematica. In this case, we're analyzing senatorial votes that have been numericized so that a value of 1 corresponds to "...
3
votes
2answers
252 views

Print characters from list with a For-loop

Suppose I have the list primary = {"b","a","e"} I want to get the following output with a For-loop (or While-loop) "b" "a" "e" My code is: ...
4
votes
1answer
285 views

An efficient way to evaluate this expression with deeply nested Do loops

Is there an efficient way to evaluate something like this? ...
0
votes
3answers
908 views

Find simultaneous roots of Sin[x] and Cos[x] using FindRoot, If, and For

I am a beginner of Mathematica, I happened to come across the following exercise which may seem trivial to the experts of this field but is hard for me to do at this level. I have the equation ...
2
votes
2answers
258 views

How do I write this matrix?

The following code gives 20 data as output. How can I make a 5*4 matrix by that data list?
2
votes
3answers
146 views

Evaluating number of iteration with a certain map with While

Beeing used to programming in C-like languages I am struggling with iterations and loops with mathematica. I am trying not to use the For command, as already lots of people recommended. I am trying ...

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