# Questions tagged [procedural-programming]

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### RecurrenceTable vs For loop : they do not give the same results. Why?

I have a second-order recurrence equation that I want to plot. I've used two different methods. The first uses RecurrenceTable, the second uses a traditional ...
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### How can I transpose SCILAB/MATLAB code with for loop into Mathematica? [closed]

How can I transpose the following SCILAB/MATLAB code into MATHEMATICA? I took a look at similar questions, but none of them seemed to provide a solution. ...
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### Efficient way of creating matrices from a very large array while avoiding singular values

I need to create matrix from a large array (>>10000 elements) for further use. I have tried Outer and ParallelTable commands, among which Outer seems to be faster when the array size is not so ...
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1 vote
43 views

### How do I use Check with Table to skip results that contain error messages

I want to run an iteration where at each step I check whether I obtain an error message, and if I do, I want to not store that result and move on to the next iteration instead. Here's an example of ...
• 351
1 vote
82 views

### Is this definition similar to a while loop?

Good morning. Reading some code in a webpage, I found this expression: X[0] = 0.5; (*edited from x to X*) X[n_ /; 1 <= n] := X[n] = Sin[n] X[n - 1] + Cos[n] Is ...
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### Incrementing a random element of an array repeatedly

Consider this code to simulate a simple instance of the coupon collector problem. We initialize an array to {0, 0} and then keep incrementing a random element until we've incremented every element at ...
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BACKGROUND call/cc is commonly used by lisp-like languages as a control flow operator. And mathematica can also be seen as a lisp-like language. QUESTION How to complete implement ...
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### FindMinimum with many Sums and NIntegrates is very slow

I want to calculate the global minimum of an equation which has several hundred Sums (I used 300 in this code), but the calculation is very slow. My code is as ...
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### All solutions that satisfy $x_{1}^{5}+x_{2}^{5}+x_{3}^{5}+x_{4}^{5}-x_{5}^{5}=0$

I want to find a combination that satisfies all the solutions of the following formula. $$x_{1}^{5}+x_{2}^{5}+x_{3}^{5}+x_{4}^{5}-x_{5}^{5}=0$$ $x_{1}$, $x_{2}$, $x_{3}$, $x_{4}$, and $x_{5}$ are ...
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### Performance improvements using Table and Compile

I'm converting a code from MatLab to Mathematica. It takes MatLab less than a second to compute it while its more than ten minutes in Mathematica. I was hoping to improve the performance. Here's a ...
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1 vote
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### Parallelization with procedural functions, e.g. AddTo, PreIncrement, and so on

I have a problem that procedural functions don't work with parallelization, e.g. AddTo and PreIncrement. At first, I thought it ...
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### How make a function NestUntilList that accepts multiple arguments?

Recently the looping construct Until was added to Mathematica in 13.1, based on the ResourceFunction Until created by Jon Mcloone. I want to make a generalization named NestUntilList. NestUntilList is ...
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### Stack Solve solutions in a loop [duplicate]

I want to solve the following equation in a loop: ...
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### Real-time function graph display

I would like to see how the graph of the function en[B, i, j, k, p] changes depending on i, j...
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### Do loop Implementation

I want to generalise the following algorithm to a loop overall possible subsets of the original set. the algorithm has the following form: ver={X41,X42,X43,X44} and ...
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### comparing lists of unequal lenghts

Suppose I have three (nested) lists A , B and Cmat where ...
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### A loop in which three indices are changed

How could this piece of code be written in the Table, or as simply as possible? ...
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### Can I use Table or something else instead of While in this case?

I have a very long code that take an extremely large amount of time. I have been using the While loop, but with each iteration, it gets slower and slower, so I know there has to be a better way of ...
• 351
117 views

### How to discard the repeating elements of a list [closed]

Lets say there is a random list of expressions : a={Sin[x], Sin[3 x], Sin[4 x], Sin[x], Sin[4 x], Sin[x], Sin [5 x], Sin[3 x], Sin[5 x]} Plot[{a}, {x, 0, 2 Pi}] ...
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### The way of converting a string to a variable in a loop?

I have 60 txt files which I want to import them into Mathematica using a Do loop. Each file contains some numbers (more precisely, a list of numbers). I want to put ...
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### Jacobian General::ivar issue

I have a differential equation labelled by eq0 and I want to use finite-difference method to solve it. First, I have to set up the system of equations ...
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1 vote
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### My ParallelDo does not work

I have to do a lot of calculations that take lot of time, and using a Do loop is simply too long. It is the first time I am using ...
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### The fastest and most scalable way to write a nested loop

The problem is to find the weights {w1,w2,w3,w4} that satisfy the condition. Which is the fastest and most scalable way (e.g. for 10000 weights) to write this ...
1 vote
124 views

### Trying to apply numerical method with Do

I am trying the following scheme to learn to implement an iteration using Do loop. I tried to implement the same method using for loop but with same errors. I, therefore, turned to the Do loop to ...
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### Sorting a list by increasing order algorythm [closed]

Im new to loops on mathematica,was wondering how could I create a function to loop through a list which finds the index of the smallest value of that list, makes a sublist from index 1 to that ...
92 views

### How to NIntegrate multiple ranges of data at the same time with an output that can be plotted?

I am trying to use the NIntegrate function to find the difference in the area beneath two 2 dimensional splines (how much area of the river bed was lost or gained from one year to the next) but, I ...
483 views

### How can I make 10 variables from a for loop?

I used a for loop to make 4 variables: For[i = 0, i < 4, i++,bi=0] But when I write b0 or ...
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### Right writing of While loop

Help me pls write While loop correctly. I have next code: ...
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### Length of a For loop [closed]

How to find the length of a For loop? Here is a simple example: For[i = 0, i < 4, i++, Print[i]] 0 1 2 3 How to find that there are in total 4 outputs using ...
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### Perform same operation along dimension of an array

If I want to add the $2\times 2$ matrix b along the first dimension of a that has $n\times 2\times 2$ dimensions I can do this ...
44 views

### How to "freeze" a parallel program

I wrote a program, parallelized it (using ParallelDo[], SetSharedVariable[] etc.), and enjoyed the wonderful speedup. ...
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### How to make my own external language cell evaluator

We can type > and select python to insert python external language cell into notebook. Then we can write python code inside it and evaluate it by pressing ...
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### Why won't my random walk work in a Mathematica Do loop? [closed]

This produces a nice random walk plot: ...
44 views

### Keep Reap / Sow results after breaking out of a loop [closed]

I am doing a long calculation where I create a list using Reap and Sow. However, sometimes this calculation gets too wild and I ...
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### How to Loop initial conditions to solve a coupled differential equation using nested for?

I need to solve the following pair of coupled differential equations and find the plots for the ground state radial wave function, the potential and the energy eigenvalue for the ground state. V''(r)...
168 views

### How to create a loop in Mathematica?

Yup, im a newbie, you guessed it. But I have been having fun solving Project Euler problems with Mathematica. I am on problem #8: The four adjacent digits in the 1000-digit number that have the ...
206 views

### Quit the loop if encounter error message

First define length-component error (personal term) : This is an error when we want to get n-th component of a list if n is bigger then the length of the list. For example, ...
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### While loop not working problem [closed]

I am new to Mathematica ,and I am trying to implement this while loop which adds all odd Fibonacci numbers less than or equal to 2 million but it keeps outputting 0 for sum. Any solutions for that? ...
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### Why is this Do-Loop taking so much time?

I have this simple Do Loop that, for some reason, takes a really long time for $h<\frac{1}{15}$. Why is this so? Is there a more efficient way in programming such a recursion? ...
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### How to use same cell for printing in a loop?

I want to manually tag images. For example, we prepare a list of images like imgList = Table[Rasterize[i, ImageSize -> 50], {i, {a, b, c}}] it gives Now I made ...
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### Save loop output in a data file

I started working on Mathematica today. I'm trying to save the result of a loop in a file as a column, very simple to do, but hard for someone who doesn't know Mathematica syntax. Here is my code: <...
207 views

### Loop over multiple variables with readable code

I've seen similar posts to this, but not with as many variables. I need to loop over 8 variables, with only two values each(1 and 2), so I can loop over the 16 possible input and output states, and ...
292 views

### Storing the data at the end of the For loop

I have a For loop ...
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### Algorithm consisting of modules returning multiple errors

I'm trying to write a genetic algorithm that will take a list of lists of reals in interval [0,1], my "starting population", "score" them according to a fitness function, append ...
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### While loop to solve a diffusion problem

Crossposted at Wolfram Community: https://community.wolfram.com/groups/-/m/t/2506329 I am trying to use a While loop to solve for a diffusion problem using the power iteration method. The code is ...
120 views

### Trying to add up values into a matrix

first post here. I'm currently completely stuck and frustrated with mathematica. In retrospective, it might had been a mistake to use it for this, I'm actually considering to somehow export the ...
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1 vote
142 views

### Monitoring Table or Do with Print

Imagine I want to track the progress of constructing a complex Table or Do object by temporarily printing the iteration number. ...
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### Efficient iteration of matrix multiplication into a table

Suppose I have a list of matrices $(A,B,C)$ and a vector $v$. I want to construct a table whose elements are sequential applications of these matrices to $v$, i.e., the first entry will be $Cv$, the ...
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I have a strange matrix like this one in the picture Now, my goal is to change all the 1s with random complex numbers of modulus 1, but if the element $a_{12}=z$, then $a_{21}= \bar{z}$, so the ...