# Questions tagged [iterators]

Questions on using and specifying iterators used in Mathematica functions.

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### A way to generalize my code for this non linear ODE problem

I am trying to solve the differential equation $y''(x) = y(x)+\sin[y'(x)]$ using "Fixed Point Iteration" over the interval $[0,1].$ Now using central difference method I arrived at the ...
46 views

### How to make this bisection code work for different equations?

I am very new to Mathematica. I have this code of Bisection Method for finding a root of a polynomial. ...
50 views

### Multiple iterators and vectors in a region

I'm interested in vectors whose coordinates are multiple of icosahedron coordinates of the vertices times $n+\tau m$ with $n,m$ integers. Then I want to see if they fall inside an icosahedral region ...
1 vote
499 views

### How to plot an imaginary number, i, power tower as done in the following way?

Can somebody explain what two variables exactly they have plotted against each other to get such graphs, and how one would go about getting this graph in Mathematica?
101 views

### How to plot an iterative function of y(n+1) against y(n) in order to analyze the convergence of real power towers? [closed]

I'm new to mathematica and was wondering how to plot an iterative graph for power towers. If there is a power tower y= x^x^x^x^x^x^... we can rewrite it as an iterative equation in the following way: ...
115 views

### How can I nest a complex function?

I am examining the mandelbrot set so I need to iterate the function f[z_Complex, c_] := (z)^2 + c Besides, I want to choose the complex numbers dynamically from ...
1 vote
91 views

### Inconsistent results solving system of equations with FindRoot

I have been trying to solve the following problem (Is basically a physics problem: an expansion of equations of state up to 1st order of the order parameter in order to solve for the critical ...
32 views

### "ListPlot" of some probability distribution of a function under "NSum"

Sir, While trying to Listplot the Probability distribution of a function under command NSum, it shows some error messages and no plot is shown. the details of the inputs written in mathematica along ...
70 views

### How to optimize code for obtaining large data set?

In an application, I need to find a region where some conditions must be true. However, these conditions are made of interpolating function solved by ParametricNDSolve. I will give a toy model example ...
144 views

### Evaluation of an iterator construct containing Sequence in Table

The following code: Table[i*j, Apply[Sequence , {{i, 1, 3}, {j, 1, 2}}]] returns the error: Table::nliter: Non-list iterator Sequence@@{{i,1,3},{j,1,2}} at ...
120 views

### Efficient alternatives to a Table based iteration

I have performed some operations using the Table iterator but I am looking for efficient alternatives to my approach. First, some preliminary code: ...
74 views

### How to implement recursive function in While loop Module, calling on other functions

I am trying to implement a module such that it " takes a distance matrix, Q, and iterates the corresponding “Bellman operator” module written above until a final cost-to-go function (i.e. J) is ...
277 views

### In a for loop, how do I assign a table of values to a new variable for every iteration?

I am trying to create a divided differences table for a set of data of depth n, specified by the user. I am not sure how to create and assign a new variable name for each iteration of the for loop. ...
277 views

### Nested floor functions

I would like to compute a limit involving a particular nested floor function. For example: ...
1 vote
69 views

### Digits product and an iteration process

I would like to create a code which gives me the square of the product of the digits of a number, with the only rule that if a number has a 0, then it doesn't count in the product (for example, if the ...
26 views

### Constructing Table iterators programmatically: how to avoid the non-list iterator error? [duplicate]

The following simple code of course works: Table[n^2, {n, 3, 15, 2}] (* Out: {9, 25, 49, 81, 121, 169, 225} *) I would then like to construct the iterator ...
410 views

### Changing iterator inside a Table?

Consider Table[ If[i == 3, i = i + 2;]; i , {i, 1, 10}] {1, 2, 5, 4, 5, 6, 7, 8, 9, 10} The above output is not what I would expect (namely ...
130 views

### Generate a sequence of all cases

There is a sequence of numbers that satisfies $a_1=2$, $a_n-a_{n-1}\in \{1,3,5\}$ I tried to enumerate all possibilities using the code below ...
101 views

At WTC2021 Roman Maeder gave a presentation about Iterators. In the presentation notebook it is mentioned that the code / paclet (Iterators-0.9.paclet) is provided as part of the presentation ...
1 vote
31 views

### Repeated calculation with neural network measurement slows down

I have a list of 200 neural nets nets0. I have to measure the output of several layers of each of them on a list of 1000 associations ...
56 views

### Generating iteration and constraint lists dynamically

I have a model for which I want to perform a set of calculations with successively deeper iterations and more constraint. In other words for a given value of a Do iterator, n, I want to: perform a ...
81 views

### Supplying a seed for an iterative method in LinearSolve

Just a quick question. Does anyone know if it is possible to supply a seed for the iterative methods in LinearSolve? I have a large sparse system, and even using some Krylov iterative solver, my ...
211 views

### Incorrect syntax highlighting? "Variables made special by use in arguments" not working

This example is obviously not useful on its own, but it will cover everything I actually need to know for a more complicated function I'm making. The example is to recreate the ...
138 views

### Exporting specific frame of ListAnimate

Imagine I have a certain list of Graphics-type objects that I then incorporate into ListAnimate ...
150 views

### Iterative function

I would like to write a bit of code that does the following. Pick a random number from 1 to 20 (inclusive) then if that number is < 15, stop if that number is > 15 pick 2 numbers from 1-20, and ...
160 views

### Repeating and Sequencing Procedures with two Do-loops

I have a Do loop where I'm looking for the value of certain parameters that respect the conditions inside an If, and with those values, a run another Do to make another calculation of an expression ...
1 vote
56 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. ...
157 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 ...
247 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 ...
323 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 ...
71 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? ...
158 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 ...
158 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 ...
60 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
90 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 ...
188 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
606 views

1 vote
82 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 ...
436 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
639 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 ...
299 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. ...
125 views

### Iterative comparison between different vectors

I have some soccer outcomes for each league round to import in a data form similar to that: ...
114 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 ...