Questions tagged [iterators]
Questions on using and specifying iterators used in Mathematica functions.
155
questions
1
vote
0answers
29 views
Custom Table, for iterating over permutations
It is common that I iterate over all permutations of 1,2...,n, either by making a table or performing a sum.
Instead of creating the set of all permutations, it would be better to iterate over them.
...
4
votes
1answer
120 views
Trouble iterating my forest fire simulation
I'm having some trouble iterating my simulation of a forest fire. I'm new to Mathematica, so apologies for poor coding. I'm sure there are far neater and more efficient ways of doing this, but I would ...
6
votes
2answers
214 views
Function to create random matrix, then a simulation. *EDIT* Create two functions
How can I write a function with parameters b, i, and j, which would return a i x j array of 0s, 1s, and 2s, but the array needs to be populated randomly with 0s and 1s which have respective ...
4
votes
3answers
284 views
Function representing a forest fire after one time step
How can I create a function that would have as its argument an array mat of 0s, 1s, and 2s where the 2s are burning trees and the function would give an array that represents the forest after one time ...
0
votes
1answer
35 views
solve for variable in iterator limit
Why can we not solve for P in the iterator limit in the problem below? How can it be solved?
...
1
vote
2answers
102 views
Can one make `Do'-Loops of arbitrary depth?
In the documentation for the Do[...] function, a loop of nesting up to any number of layers is supported. But to apply their function, one needs to know ahead of time how many layers of loops they're ...
2
votes
1answer
119 views
Strange indexing behavior by Table
Maybe I do not understand how Table works, but I find this very confusing and it took me a long time to debug because this was part of a much more complicated routine.
I am trying to build an array ...
2
votes
1answer
46 views
Two different variables in a Do Loop
I am trying to use the code developed by @Alex Trounev here: Numerical solution of an iterative equation for different kind of q. I am not sure how to incorporate ...
1
vote
0answers
46 views
Need help with NestList [closed]
NestList::intnm: Non-negative machine-sized integer expected at position 3 in NestList[#1 + t&, 0, 8.].
What does the above error mean and how can I refer to result of ...
0
votes
2answers
60 views
Using condition for each element of a matrix
I'm trying to write a code so that for each element of matrix C2 if the element i,j is equal to element j,i and it is equal to 1 then it adds one to a variable and if not it adds one to another ...
1
vote
1answer
129 views
Fixed point iteration with While or Do Loop
I need to write a while or do loop to perform the iteration $x_{n+1}=Cos(x_n)$ with initial value $x_0=1$ and stops when the absolute value of the difference between two consecutive iterations is $|x_{...
2
votes
2answers
106 views
Using iterative functions to specifically sort a list
The following code sort the list li in a such way that consecutive terms $t_n,t_{n+1}$ are of the from ...{x_,y_}, {y_,z_}.... i....
1
vote
1answer
48 views
Use of a For/While loop inside another For/While loop for dual integration [closed]
Can anyone please give suggestion for using For/While loop inside For/While loop for integrating a function with respect to two variables say for-
$\qquad r = (x^2 + (a/y^2))^(-1/2)$
Integration is ...
5
votes
1answer
107 views
Nest or fold a series of geometric transforms
I have a requirement to perform a series of GeometricTransformation[]s using the AfineTransform[] function. I use these to set ...
0
votes
1answer
93 views
How I can plot the below map?
I have tried to plot the following map:
$\qquad
\begin{cases}
y_{n+1}=r y_n^{x_{n+1}-x_{n+2}}\\
y_1=x_1-x_2 \quad
\end{cases}$
using the code shown below. The error I have got is that
x[1] - x[2] ...
1
vote
1answer
30 views
Plotting an iterated piecewise function with endogenous nodes
I am trying to plot a piecewise function that I can define recursively, where the nodes are endogenous as well. Basically, $f(l)=a^{t}$ when $l \in \left( \frac{\mu}{\alpha^{t-1}(1-\alpha)+\mu(1-\...
1
vote
1answer
67 views
Code to generate many Do-loops, where the $i$-th loop has upper bound given by $f(i$)
How do I get Mathematica to run an arbitrary number of Do-loops, where the i-th loop it upper bound given by some function $f(i)$? I badly need help with this.
Let's denote the desired code by ...
6
votes
1answer
385 views
Why can't I create {a,a,a,b,b,b,b,b,c,c} from x={a,b,c}; f={3,5,2}; Thread@Table[x,f]?
ClearAll[x, f]
x = {a, b, c};
f = {3, 5, 2};
Thread[Table[x, f]]
produces
Table::nliter: Non-list iterator f at position 2 does not evaluate to
a real numeric ...
1
vote
1answer
147 views
How do I evaluate my functions over a range of values? [closed]
I want to use the list of data which will come from MapData1 (in code); the first element is θ and second is Action(I). I want to use this Action(I) and Angle(θ) in ...
8
votes
1answer
180 views
How can I use a loop with an iterator in order to evaluate a function?
I'm trying to evaluate a function, that depends on two variables, in a specific set of values. I will write an example, but my system is more complicated.
...
4
votes
1answer
90 views
Iterative comparison between different vectors
I have some soccer outcomes for each league round to import in a data form similar to that:
...
2
votes
1answer
65 views
Stop `(Parallel)Table` evaluation when wanted case is found
I have to go through a long list of evaluations, for which I suppose Table instead of For or ...
3
votes
1answer
59 views
Making a recursive function
Suppose I have the following functions:
a[x_] := x
b[x_] := x (a[x]) - a[x] + 1
c[x_] := x (b[x]) - b[x] + 1
d[x_] := x (c[x]) - c[x] + 1
as you can see each ...
0
votes
1answer
109 views
Does lower case n have some significance in the Wolfram Language? [duplicate]
I am truly confused with this one, and maybe someone could help me to clear this up.
I am running a Table[] that runs multiple neural networks in series on OpenAI'...
1
vote
0answers
57 views
Is it possible to generate iterators dynamically during parallel processing?
I have a parallel processing code written in Wolfram Mathematica, similar to:
...
3
votes
2answers
126 views
0
votes
1answer
64 views
Problem with iterations of Prepend/While
I am doing some work with black-scholes and am trying to find random interest rates based on some given information. This is my original code:
...
2
votes
2answers
73 views
How to iterate through a lists of lists and delete a certain element?
Say I have a list of lists such as
l1 = {{a, 2}, {a, 5}, {b, 3}, {b, 9}}
How would I iterate through the list and delete all the lists with the first element b ...
4
votes
1answer
247 views
How to nest multiple functions with multiple variables
I'm trying to solve coupled equations by using iteration. There are two functions $G$ and $H$ that I need to find. In the code, G and H are actually lists of numbers. I start by using a simpler ...
1
vote
2answers
51 views
1
vote
1answer
39 views
Iterate through union of lists to correspond to each element a list of names of the lists to which the element belongs
Say I have several lists L1, L2,L3 an I want to correspond to each of the elements of Union[L1,L2,L3] a list of list names to ...
1
vote
2answers
75 views
0
votes
1answer
149 views
Automating a large operation by making a function
I would like to automate the following operation. To be transparent I shall put my code into separate chunks and explain the process. Suppose I have the following:
...
1
vote
0answers
85 views
For- loop which can reuse updated values [closed]
Eout = E^x ;
For[kz = 1, kz < 4, kz++,
Print[Eout1[kz] = Eout];
Print[kz]]
The output is
E^x
1
E^x
2
E^x
3
But what ...
4
votes
3answers
520 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 "...
1
vote
2answers
93 views
How can I iterate across a list of triples?
i just started to use Mathematica and I`m completely new to programming. So i'm some kind of noob in the purest form..
I'm trying to transform a coordinate system into a different one. I'm using <...
0
votes
1answer
117 views
Creating matrices using a Do-loop
Here is an image of current assignment; I am not able to do step 6 to 8
When I try to do the Do-loop, it states that the {i, j} does not have appropriate bounds.
...
1
vote
1answer
54 views
ListCountourPlot does not show any result [closed]
I was trying to show the heat conduction of Laplace equation problem.But the plot does not show properly
...
1
vote
1answer
80 views
Defining iterative algorithms [closed]
Assume the iterative algorithm of interest to be as follows:
...
1
vote
2answers
569 views
Multivariate Newton-Raphson method and FindRoot module [closed]
Let's suppose that we have the following equation
...
2
votes
1answer
431 views
Golden section search method that terminate after $n$ iterations
I am attempting to code a program that executes the golden section search method, and I would like to terminate the computations after $n$ iterations, where the user decides what $n$ is. My code works ...
12
votes
3answers
509 views
How to programmatically specify multiple iterators?
How to use Row[Table[{B[i],0,i},{i,0,2}],","] directly in Do command? I mean that the following command
...
3
votes
1answer
1k views
Encountering 'Error: Set::setraw: Cannot assign to raw object' during procedural function definition
Sorry for the rather vague title, but I don't know what is wrong with my code.
Here is a Ruby version of what I'm trying to do:
...
2
votes
1answer
132 views
How to change the dimension of a tensor inside a loop using XAct/XTensor?
I'd like to define a function CDOrder[k] to compute the k-th order covariant derivative of a vector ...
0
votes
0answers
131 views
Operation on sublists with multiple arguments
I have a list and add only the values which are > 0 with:
Total[Cases[mylist, x_ /; x > 0]]
How to do this if I now have a list of sublists?
...
4
votes
2answers
132 views
use Range to form a vector
I have a function
y[k_]:={0,0,0,I*t^k};
and I need to get a vector
Join[y[1],y[2],y[3],y[4],y[5],y[6],y[7]]
and it is just ...
6
votes
4answers
570 views
Applying loop functions with input list of iterators
Given an iterator, I am trying to generate a table of all possible pairs of values. The form of the iterator I'd like fixed, because I want to run other loops with it as well. The closest to what I ...
0
votes
0answers
102 views
Iterating a Module
I have a Module that can act on other Modules, which is given as
Kk[EE,p,z1,z2,z3,K_func]
and I am trying to iterate it, such that
...
1
vote
2answers
114 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 ...
1
vote
3answers
275 views
integral equation iteration
So I am trying to recreate the numerical treatment in this papir (https://journals.aps.org/prb/abstract/10.1103/PhysRevB.29.130), equation 3.7. The main point is to try to solve the following equation
...
