Questions tagged [iterators]

Questions on using and specifying iterators used in Mathematica functions.

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93 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
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1answer
99 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
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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 ...
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0answers
43 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 ...
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2answers
56 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
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1answer
88 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
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2answers
105 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
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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
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1answer
103 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
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1answer
91 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
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1answer
29 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
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1answer
65 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
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1answer
383 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
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1answer
99 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
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1answer
177 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
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1answer
88 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
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1answer
63 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
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1answer
57 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 ...
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1answer
106 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'...
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0answers
55 views

Is it possible to generate iterators dynamically during parallel processing?

I have a parallel processing code written in Wolfram Mathematica, similar to: ...
3
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2answers
125 views

Iterating with Do rather than NestList

This code below works fine for me. ...
0
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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
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2answers
67 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
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1answer
209 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
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2answers
49 views

Nested Table With Iterable Bounds

I have a set of data that looks vaguely like this: ...
1
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1answer
34 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 ...
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2answers
75 views

How to iteratively (or most efficiently) create such list?

Update A very crude attemp ...
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1answer
145 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
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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
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3answers
474 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
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2answers
85 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
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1answer
101 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
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1answer
53 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
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1answer
79 views

Defining iterative algorithms [closed]

Assume the iterative algorithm of interest to be as follows: ...
1
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2answers
500 views

Multivariate Newton-Raphson method and FindRoot module [closed]

Let's suppose that we have the following equation ...
2
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1answer
376 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
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3answers
503 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
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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
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1answer
124 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
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0answers
128 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
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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
559 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
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0answers
95 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
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2answers
109 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
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3answers
266 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 ...
1
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1answer
60 views

How to implement recurrence operations efficiently?

This question is related to this one. I basically want to partition a volume recursively. Consider a volume as vol = ExampleData[{"TestImage3D", "MRbrain"}]; ...
2
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0answers
52 views

Using Iterators within the WebSearch Command

I am currently trying to use the WebSearch command within Mathematica to search names from a Dataset that I have already imported. The names that I am trying to search are located in the 4th column of ...
1
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1answer
140 views

Iterator order breaks Table

Evaluating the following Table expression ...
0
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0answers
106 views

Variables defined modulo $\pi$ and avoiding singularities; phase plotting for a map

I have the following $2$-dimensional implicitly defined map ...
2
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1answer
149 views

How to plot a phase portrait of a map for many initial points?

Suppose I have a 2-dimensional map $x_{n+1} = f(x_{n},y_{n}), \quad y_{n+1} = g(x_{n},y_{n})$, and a number of initial points $(x_{0}, y_{0})$ in some given range. I take each initial point and ...