# Questions tagged [programming]

Questions on writing non-trivial programs in Mathematica. Do not use this tag for questions on plotting/graphics or for questions on doing mathematics with Mathematica, where the focus is more on the math than the program.

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### Certain search in list

A list $LL$ of $n$ real numbers is given. For each element $e$ of $LL$ to find the position of the closest to the right element of $LL$ which is at least twice bigger than $e$ and return it. If ...
39 views

### Hierarchically adding {…keys..}->value to an association

Given a list of keys {"a","b","c"} and a value 3 (associated to the last key) I want to define a function that is equivalent to ...
60 views

### Define a function with specific permutation properties

I want to define a function evaluate[f_[x__]] which acts on an arbitrary function f[a,b,c,d]. The function ...
61 views

### Find critical radius in percolation

I would like to examine the percolation from the left edge to the right edge on random lattice. Suppose I have a rectangle with N random points on it. ...
129 views

### How to put solutions of mutiple DEs with NDSolve in table

I have $N$ differential equation for each $s \in {1,2,...,N}$ on the domain $x \in [1,2]$ of the form (e.g.) $xf_s'(x) + \log(xs) f_s(x)+1 = 0$, with the boundary condition $f_s(1) = e^{-s}$ Now I ...
93 views

### Mapping a function f[xi_,xj_] over a list {x1, …, xn} with the i < j restriction

I am often facing the situation where I have a list $\{...x_k...\}$ and where I want to compute: $$\{...f[x_i,x_j]...\}\text{ with }\ i<j$$ Unfortunately, I have not been able to find an ...
71 views

### Import and merge PDF files

I have a folder with several pdf no more than 50, I would like to import them to be disordered and that the output was a single pdf (you can imagine it as a proof of form A and we want to produce form ...
143 views

### Is it possible to create lookups on temporary symbols that still allow the symbols to be automatically removed?

Is there some way to create lookups keyed on Temporary symbols that somehow avoid the referencing of the Temporary symbols, ...
254 views

### Find the 3D region containing the origin bounded by given planes

I'm writing a code to generate the Wigner-Seitz cell of the reciprocal lattice for a given set of lattice translation vectors. For example, consider the Body Centered Cubic (BCC) lattice whose basis ...
36 views

### Wrapped Association into a “structure”: how to define Equal[] and what are the good practices for package dev?

Using a nice answer https://mathematica.stackexchange.com/a/197936/42847 I got from a previous question I define: ...
91 views

### Efficient manipulation of Associations passed to functions, how-to? [duplicate]

I have some data wrapped into a MyData[data_Association] "structure". My Association contains some big arrays and I do not want ...
45 views

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33 views

### A newbie question about the use of the FourierSeries functions

Although I have had no previous experience with the Mathematica Fourier Series functions ( or package ), I am writing a tutorial on Fourier Analysis and Transformations in a Mathematica Notebook, ...
248 views

### Finding the path in a graph from A to B then back to A with a minimum of shared edges

the problem is to find cycle from A to B back to A, so that the path B-A would use minimum edges from path A-B. The graph is undirected and can have cycles. The paths don't have to be shortest, they ...
33 views

### How to use the Mathematica [duplicate]

I am a new learner for Mathematica. I know just some basics of Mathematica, I can plot simple graphs. But, sometimes I have to plot some complicated graphs. Then, I am unable to plot that particular ...
509 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 ...
23 views

### CDF and ElasticSearch [duplicate]

I have an large amount of data, in the terabyte range, in an ElasticSearch instance. The data is on an network air gapped from my Mathematica instance and I'd like to have an app to examine the data ...
80 views

### How can I use Compile to implement recurrence?

I am trying to make the code for the following recurrence. Here wjoin[[i]] is used for calling values from a data set and a is a ...
312 views

### Plot of histogram similar to output from @risk

In order to analyze simulated data, @risk provides a histogram with handle bars, so that we can move these handles to see what proportion of data are on each side. For example, . I am trying to ...
29 views

I'm trying to create custom appearance for PopupMenu with the below code. The problem I have is with the menu items which are displayed as values instead of labels. ...
28 views

### Why is an integration error appearing during this code?

I'm really confused about this to be honest. If i evaluate approx[x,k] for some k, and then input the list into the Plot function, I get a plot. But if I try to use approx[x,k] directly, I get an ...
52 views

### Problem with PopupMenu: Its values don't update dynamically

I have a problem with PopupMenu inside DynamicModule, its values don't update dynamically as they supposed to. The example below ...
60 views

### How to get Mathematica to loop two functions at once

So I know how to get half of this problem. I am trying to run a loop that combines the following two function at once so I can see from my index i if any number satisfies both conditions. TO get the ...
140 views

Cross-posted: https://community.wolfram.com/groups/-/m/t/1625808 Answer posted on Wolfram Community I'm creating an interactive UI which allows the user to import data from a spreadsheet, perform ...
86 views

### Solving x'[t]+a*x[t]==0, listing all the solutions, trying to get the value -1x<1 and all corresponding value of a

I am Trying to solve x'[t]+a*x[t]==0,x==1, for x with {t,0,10} using NDSolve. ...
56 views

### How to make a table for loops?

I have a code given by ...
90 views

### a recursive function using memoization

I have looked at a lot of these cases, e.g. Can one identify the design patterns of Mathematica? and the included ones. My trimmed example, here establishing the 'initial conditions' (where the ...
128 views

### Complex partial fraction expansion

I would like to have a tool for partial fraction expansion of polynomial quotient $$\frac{P(z)}{Q(z)},$$ where the order of the polynomial $P(z)$ is less than that of $Q(z)$. The output of the ...
54 views

### Implementing Dual Unit from Dual Numbers

I'm trying to implement the dual unit $\epsilon$ defined by $\epsilon^2 = 0$ into Mathematica but I'm having trouble defining $\epsilon^n = 0$ for $n\geq 2$. In this answer they simply use ...
41 views

### Defining a function that affects indices

I want to define a function, that works like this: f[3v[1,2,3]] = 1/3 v[1,3,2] + 3^2 v[1,2,3] f[2v[2,2,1]] = 1/2 v[2,1,2] + 2^2 v[2,2,1] Basically, it should ...
142 views

### How to implement split-complex numbers?

For those who do not know, the split-complex numbers are an analogue to the complex numbers where J is defined such that $J^2=1$ but $J\ne\pm1$, so they are all of the form $a+bJ$. By using ...
76 views

### Calling a notebook from a different notebook

Basically I have a notebook (let's call it nb1) that when evaluated yields one number when I specify some parameter $\alpha$ (in nb1). I want to call nb1 in a different notebook (nb2) using for ...
98 views

### How to resolve the fail when applying a user-defined solver?

The user-defined function pdetoode and pdetoae, developed by @xzczd, is very useful to deal with a PDE system when there is ...
1k views

### Sisyphus Random Walk

A Sisyphus Random Walk evolves as follows: With probability (r) you advance the position of the walker by +1. With probability (1-r) the walker resets at x0 = 0. To simulate the probability of reset ...
70 views

### How can we make an algorithm with the A* method in Mathematica with 5 different flight routes? [duplicate]

I need to find the shortest path with the A* algorithm using Mathematica. I have 5 different flight routes with coordinates. They start and end at the same point. Between every point there is a wind ...
164 views

### How to print chess board with array? [duplicate]

I am doing n-queen implementation with my own algorithm and I get solutions with Number.But,I want to get output with actual chess board. This is my piece of code. ...
108 views

### What does this code mean? [closed]

Here solutions is array . I need to know why this code is written.Please help me. ...
103 views

### How to use external Mathematica Code? [duplicate]

I have a Mathematica Notebook with a function that i would like to be able to access from another Notebook without having to have the first Notebook open. The functions calls other functions in the ...
85 views

### Transforming a conic to it's standard form

Suppose a conic is given.I need to transform it to standard form.So i tried like this: ...
78 views

### how to sort a list without build-in function

I want to sort a list like below.Without using the build-in function so I tried this: ...
157 views

### Solving two coupled PDEs with the pdetoode function posted on this site [closed]

I want to solve two coupled PDEs with pdetoode function: feq = {D[ϕ, t] + U*D[ϕ, y] - D[ϕ, {y, 2}] - (s0 - 1/20*y^2)*ϕ == 0} and ...
202 views

### How to Write Stand-alone Mathematica Projects/Programs

I wish to write several stand-alone projects/programs using Mathematica because of its easy-to-use graphics. I could use Python for this, but Mathematica has built-in graphics that would be better ...
50 views

### Making a function $f(n)$ tangential to another function $g(n)$ by choosing appropriate constants

I have two functions $f(n) = 1/(1+n) + b, (n \geq 0,b \geq 0)$ and $g(n) = pn^2 + qn + r$. Assuming that I know the value of $p, q$, and $r$, I am trying to find a value for the constant $b$ ...
125 views

### How to randomly generate Tree or Nested List of Function in Mathematica?

In detail, I want to generate randomly something like Divide[Add[X,Times[X,Y]],Times[X,3]] or {Divide,{Add,X,{Times{X,Y}}},{Times,X,3}} (Specified Function(# of argument is from 2 to 5)) + ...
178 views

### Mathematica is not responding for very large numbers

So, I am having Mathematica 11.3 and trying to evaluate 2^1,000,000,000. When I am trying to show the output in its full form to manipulate the digits, Mathematica stops responding. I am having 32GB ...
108 views

### Check if number is in list

I have a nested list, but don't know how long the individual lists are. Sometimes they may be 2 numbers long sometimes 1000, so i need to check if theres is a number at position 6 but i doesn't ...
68 views

### Is there packages can help read, analyze or understand MMA codes? [closed]

Sometimes, I think that it's difficult to learn high level codes, or even when looking back on some long lines of codes I myself had written, espectially when lots of pure-functions was used, so I'm ...
53 views

### Fold/ NestList/ etc in MCMC loop for optimisation

I am trying to simplify and optimise an old loop code I wrote. Since Fold and NestWhile use the results of the last iteration in the new iteration, I would like to use them in order to get rid of Do ...
I used "Table" to calculate and plot the following complicated function. First, we choose an initial value for $G$ and other parameters, but at later times $G$ changes with function $I_a$. ...