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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2
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1answer
1k views

Executing a .m file from the Linux command line

I have some code in a file named Demo-3.m, It can be evaluated in Mathematica 9. The final expression in the file is ...
2
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2answers
165 views

How to unprotect GeneratingFunction

I'm trying to add custom downvalues for GeneratingFunction, and to do so I thought I just had to Unprotect it. However, that ...
2
votes
2answers
2k views

Product of Fibonacci numbers using For/Do/While loops

I want to find the product of the first 20 Fibonacci numbers (the fibonorial). I want implementations using While, Do, and ...
2
votes
2answers
719 views

defining recursively a function with multiple if conditions

I am trying to recursively define a function which satisfies the following system of equations and which depends on two parameters $n$ and $l$, $$ \begin{align} A(x, n, l) &= F[ A(x,n-1,l) ]\\ ...
2
votes
1answer
774 views

Optimizing a function involving NDSolve results in error messages

I want to minimize a function f with NMinimize but an error occurs that says: ...
2
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1answer
187 views
2
votes
1answer
95 views

Map and Scan ignore HoldFirst

I am trying to write a simple function that takes a list of data and outputs it to a file. I'd like the name of the file to be the same as the variable that holds the list. It seems that giving a ...
2
votes
2answers
112 views

How to plot points with error circles on map with latitude/longitude grid

I am currently working on a project to model the location of icebergs in the northwest atlantic. When an iceberg is sighted, an error circle is plotted around it (with a bivariate normal probability ...
2
votes
1answer
132 views

What is the correct way to break a long expression across multiple lines?

This is probably a very simple question and I am probably not using the right keywords in my search; but I have a long expression that I would like to break across multiple lines to improve ...
2
votes
1answer
95 views

Please explain this while-loop

Code: ...
2
votes
1answer
316 views

Converting a nested for loop from MATLAB

In MATLAB I have the following series of nested for loops that update a matrix. (It's not my code, but someone else's that I'm trying to replicate - I don't know ...
2
votes
1answer
272 views

Call Functions From File Without Modifying Context (Sandbox)

Let's say I have file named test.m containing test[arg1_] := ( Print[arg1];) What is the best technique for calling test like ...
2
votes
1answer
206 views

Is it possible to treat starting values as variables?

I have a problem where I am using FindRoot a gazillion times over a grid of parameters. I need to allow the starting values to vary a bit with the parameters to get it to converge. Here is a simple ...
2
votes
1answer
155 views

Rookie mistake in defining a function with Modules?

I can't figure out what's wrong with this piece of code. I'm trying to define a function that counts the occurrences of x, y and ...
2
votes
1answer
126 views

Import a file only if it contains a certain pattern

Let's say I have three files containing: File 1: x y z 1 4 6 File 2: x y z 2 5 9 File 3: x y z 5 4 8 My goal is to import the data from a file only if in ...
2
votes
1answer
232 views

Computing closest set of points to each point in large set — running out of memory (arrays unpacking)

I have a large set of points in 3D and I'm trying to identify all the points that lie within a certain distance of each point. Then using this data store the vector between the pairs of points. I ...
2
votes
1answer
213 views

Fighting Less::nord at the root: Any unintended consequences?

After being plagued too much by Less::nord and companions, I've decided to try to fight it at the root: The comparison operators. I noticed that typically, the bad ...
2
votes
1answer
126 views

How to speed up my code about Divisors?

This code is about PE496 In[21]:= ParallelSum[n*Count[Divisors[n^2], a_ /; n < a < 2 n], {n, 1, 10^5}] // AbsoluteTiming Out[21]= {5.987342,10724527832} I ...
2
votes
1answer
69 views

How to package a function for export?

I often post code for functions on Stack-Exchange, and then later find that they are unexecutable - that people can't use them because I mistakenly omitted some private functions or values that are ...
2
votes
1answer
87 views

Probability evaluation fails with equals condition

The following evaluation fails (the result is just the copy of the input) $$\text{Probability}[0<x\leq a | x-y=t,\{x\ {ExponentialDistribution}[\lambda ],y\ {ExponentialDistribution}[\lambda ...
2
votes
1answer
81 views

CreateDocument options needed to suppress the default notebook menu

What are the options needed in Mathematica 10 to suppress the menu on top of any notebook created with CreateDocument? For example, the Messages window as well as the windows generated by ...
2
votes
1answer
111 views

How to program a clickPanel for chemical elements (like a periodic table)?

The command ColorData["Atoms", "Panel"] indicates RGBColors of "Atoms" by clicking a panel. As I don't want to reinvent the wheel, I asked myself: How to ...
2
votes
1answer
148 views

How can I rewrite my code to make it simpler?

Two months ago,I written a function IRobot to caculate the $I_{xx},I_{yy},I_{zz}$ and $I_{xy},I_{xz},I_{yz}$,shown as below: ...
2
votes
1answer
730 views

Calculate mean square displacements for different particles from a excel file

I have the particle movement data in the following format: ...
2
votes
1answer
308 views

How does FindInstance work?

I was asked a question one day: find an integer n such that the first five digits of 5*7^n is 12345. It's very nice that I can quickly write code like this: ...
2
votes
1answer
205 views

Combining two notebooks

I have a notebook which contain all the variables and defined functions. I want to do two tasks. As an example, I want to find the density and energy which have equations in terms of above mentioned ...
2
votes
1answer
93 views

PaneSelector and options in a Module

Consider the following snippet of code: ...
2
votes
1answer
101 views

How to define the Bernstein function like the built-in BernsteinBasis?

We know the Bernstein function defined as below: $$B_{n,i}(u)=\binom n i u^i(1-u)^{n-i}$$ And we define $B_{n,i}(u)=0$ when $i<0 $ or $i>n$ In addition, the first derivative of $B_{n,i}(u)$ ...
2
votes
1answer
732 views

Mathematica TCP socket client toward Trading Platform

I'd like to connect Mathematica with my Italian electronic trading platform. To connect I need to open a TCP socket client towards the trading platform and send a string command. The high-level ...
2
votes
1answer
83 views

Fastest way to select the longest cell

I'm trying to learn low-level notebook programming and I have a question. Is there faster way to select the longest cell in a notebook than this: ...
2
votes
1answer
287 views

Range of stability for iterative map

Using linear stability analysis, I would like to compute the range of stability of the fixed points and the 2-cycles of the following iterative map: $x_n = x_{n-1}^{2} - 3\mu$. Setting $x = x^{2} - ...
2
votes
1answer
432 views

Cournot Equilibrium

I'm trying to determine reaction functions of a Cournot equilibrium for $n$ firms using the same optimal condition, using the fixed point method. This is the method I'm using: ...
2
votes
1answer
68 views

Are there methods to serialize and deserialize large calculation runs? [closed]

I have a fairly large calculation to map an electric field over large areas (square kilometers). This runs for a fairly long time. Are there ways to serialize the current state of a running ...
2
votes
1answer
131 views

Need help looping a notebook evaluation

I'm a new user and would like to find the minimum value of soln1[30] obtained after repeating the following evaluation (below) for 1000 cycles (for instance). I can obtain sequential values of ...
2
votes
1answer
162 views

Discard functions with wrong symmetry?

I have functions of x, where x is the polar angle of spherical coordinates, i.e. ...
2
votes
1answer
280 views

Can Mathematica help a theorem to be alive?

We are used to do limits by means of $\epsilon, \delta$. This is the first step an student encounters limits. Using $\epsilon$ and $\delta$ leads him to be familiar to Logic. I have taught limits and ...
2
votes
2answers
61 views

Need help updating an old Mathematica worksheet

I found a notebook that symbolically applies the multiple time scales method to any differential equations. I don't like just using other people's code so I am going through the author's work line by ...
2
votes
1answer
84 views

ControlType -> None Vs. Module inside Manipulate (i.e. making everything local)

I'm building a program on another one made available in the Wolfram Demonstration Project. I've noticed that in the original code (working flawlessly) many variables were made local inside the ...
2
votes
2answers
181 views

Solving a dynamic program via recursion

I'm trying to use recursion to solve a joint inventory/ dynamic pricing problem as in monahan, petruzzi and zhao 2004. I tried to solve for y[t] and ...
2
votes
1answer
144 views

Piecewise function with user-input interval

I would like define a function g[data,bins,x] which is a piecewise constant function taking value data[[i]] in the range ...
2
votes
1answer
72 views

Evaluate only one from a set of procedures

Let's say I've got a list of procedures: {Print[1];, Print[2];, Print[3];} And I want to only evaluate 3rd one: ...
2
votes
1answer
193 views

Differential operator involving permutations

I would like to construct an operator in Mathematica of the following form, $$D_i=\partial_i +\sum_{i \neq j}^n\frac{1}{x_i-x_j}p_{ij}, \quad i=1,...,n$$ where $p_{ij}$ is a (symmetric) permutation ...
2
votes
1answer
235 views

Optimal image quality using Rasterize Function

Based on previous posts about plotting two y axes on the same x axis, I wrote this function: ...
2
votes
1answer
105 views

How can I invoke the solution of NDSolve to determine a parameter in my equation just inside NDSlove?

I am trying to solve a differential equation by NDSlove for $h(x,t)$. It reads $$h_t=h_{xx}-V_h-\lambda(t)$$ where $V_h$ is a given function of $h(x,t)$ denoted by ...
2
votes
0answers
88 views

How to efficiently find parts of a string with beginning and ending specified?

I'm trying to find specific URL addresses from a html document. The addresses can be found between the strings "href=\"" and "\" class=\"listing". The problem is not including strings like this: ...
2
votes
0answers
75 views

How can I do multiple (double) integral with periodic boundary conditions?

I am trying to do a simple double integral $\int_0^l \left[\int_0^l h^3 h_{xxx}dx\right]dx$ with periodic boundary conditions $h[0,\tau]=h[l,\tau]$ $h_x[0,\tau]=h_x[l,\tau]$ ...
2
votes
0answers
95 views

Mod[1.2, 0.2] is not equal to zero

I'm new to mathematica but this doesn't seem to make any sence In[1]:=Mod[1.2, 0.2] Out[1]=0.2 Why is it not zero? Edit: This is what I wanted to do: ...
2
votes
1answer
74 views

Using HoldFirst but not wishing to hold everything

I have a DynamicModule in which I go through some data analysis and keep or reject the results. Here is a toy example of what I am doing. ...
2
votes
0answers
128 views

Maximizing Large Multivariable Function over Region with Parameter Constraints

Brand new Mathematica user here. I have a complicated function to maximize, and thought I would try software like Mathematica instead of taking derivatives by hand. I found some Mathematica ...
2
votes
0answers
72 views

Simulating a system of nonlinear ODEs?

I was trying to simulate a system of ODEs on Mathematica in an effort to try to understand how to muck around with Mathematica but for some reason the following lines of code do not yield any results; ...