Linked Questions

0
votes
1answer
520 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
45 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 ...
454
votes
37answers
98k 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 ...
179
votes
3answers
39k 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 ...
39
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. ...
56
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
525 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
644 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
969 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. ...
5
votes
7answers
334 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]...} ...
5
votes
1answer
466 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, ...
7
votes
2answers
425 views

CUDA image processing

I am having an issue with image processing involving CUDALink. ...
3
votes
2answers
706 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 ...
9
votes
2answers
252 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
489 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 ...
10
votes
1answer
503 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: ...
3
votes
1answer
1k 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
175 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 ...
5
votes
1answer
404 views

Random walk in one dimension — meeting of two particles

I'm new to Mathematica and still teaching all by myself, hope you bear with me. I have the code: ...
2
votes
2answers
462 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 ...
4
votes
3answers
344 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 "...
2
votes
2answers
251 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
131 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 ...
0
votes
3answers
687 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 ...
3
votes
2answers
188 views

Correctly defining the return of a procedure

I am sort of new to mathematica and I am struggling with how to correctly set the return of a specific function which is a procedure. I am give the following task: Given the map $x_{n+1} = r x_n (1-...
3
votes
2answers
141 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: ...
1
vote
3answers
241 views

Extracting a 2 x 2 matrix from a 9 x 9 matrix [closed]

I have the following code: For[i = 1, i <= 9, i = i + 8, For[j = 1, j <= 9, j = j + 8, Print[k[[i, j]]] ] ] The code prints a column of the ...
0
votes
2answers
531 views

How to write if statement and for loop? [closed]

I am trying to write a function that will find a sum of all diagonal elements of matrix. I don't know how to do it correctly. This is how I tried do do it. ...
0
votes
1answer
459 views

ListPlot in a Loop [closed]

I have the following program which generates the plot from a data list(i.e. Data1). However I want to print some plots for some values of the parameter "a". How would I proceed to print the scatter ...
1
vote
2answers
93 views

What is wrong with the Mann iteration?

I have written the Mann iteration's code for the mapping $\frac{z}{1+z^2}$, in Mathematica, but it is very slow. In fact it needs more than 200 seconds for obtaining 17th iteration, while Matlab does ...

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