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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1answer
178 views

Pattern match with Table for matrix dimension check

In Mathematica, often an expression involving matrices will encounter dimension mismatch errors, like we are multiplying a 3x2 matrix to a 3x4 matrix. Below we define a new symbol Dim, which can be ...
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1answer
226 views

Why does memory run out when adding same-sized matrices in a loop?

I have written a module that it generates a 101x101x51 zero matrix at first. At every iteration, it generates a list by funct1 and based on this list, if list is empty it gives the previous result. ...
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1answer
79 views

How to improve this function that selects parameters from arbitrary distribution using Recursion?

Below, I have defined a function using Which to select model parameters based upon various conditions. My questions are: Is there any danger in writing this function using Recursion? Is there a more ...
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1answer
40 views

Why does this cause an error? [closed]

In[73]:= f[x_] := Save["C:\\Users\\user\\Desktop\\file", x <> x] f["###"] During evaluation of In[73]:= Save::sym: Argument ...
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1answer
74 views

converting DO loop into NestList form

I would like to rewrite this Do loop using NestList. Can you help me? ** DO loop ...
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1answer
32 views

New output cell generated for each run of a GraphicsGrid - is there a way to simply update the same output cell each run?

I have a Code cell that generates a set of plots in a GraphicsGrid[]. Each time I execute the Code cell, a new Output cell is generated. Is there a way to simply update a single output cell instead ...
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1answer
65 views

Data file organized in strings

I am working in a data set : The original question, They are strings of thousands stars,and each one contains a lot of parameters, and the following item is called identifies, they are the names ...
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2answers
155 views

Exctrating data information from a file.txt

I really did previous long search in the site and I couldn't find any answer that might help me. So I am asking it. I have the following data set, ...
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1answer
60 views

How can I assign a vector unknown function to solve the ODE system?

I noted that using non-scalar variables is convenient when a system of differential equations is governed by a process that may be difficult to express symbolically. Taking a example from the tutorial ...
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1answer
49 views

Programming a series involving alternative log expressions

This is likely my error but I cannot see it. I define a vector: x1 = {{{2, 2}}, {{2, 1}, {3, 1}}, {{3, 2}}, {{2, 1}, {5, 1}}} If x1[[ i, 1,2]] is 2, I would like to find $(\log$ x1[[ i,1,1]]$^2$). ...
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votes
1answer
128 views

Turning a 2D 3 body problem into 3D not so easy?

I have programmed a 3 body problem, that can in theory work for more than 3 bodies. I apologize in advance for the length of the code that I posted, I don't really know how much one would need to ...
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1answer
113 views

Need help in understanding code [closed]

I am just beginning with Mathematica. I have received this code to study. I am not able to follow this particular section. I have tried looking it up on many forums, with no answer. Can you help? ...
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1answer
171 views

Is it possible to build/simulate/extract data from a System Modeler model completely inside a notebook using the MathModelica language syntax?

See examples in: http://www.mathematica-journal.com/issue/v10i1/contents/MathModelicaPaper/MathModelicaPaper_2.html It seems to be ruled out by the statement (Chapter 2 intro): "The subset of the ...
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votes
1answer
47 views

Help with programming(using list) [closed]

I would like to make a program which gives me what is the greater natural number "n" less than an arbitrary given natural number "k" which satisfy: for each prime divisor "p" of n, p^2-1 divides n. I ...
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votes
1answer
146 views

For-loop only executes first line in body [closed]

I have a simple For[] loop: ...
0
votes
1answer
424 views

Obtaining the envelope of an oscillating function and perform fitting

There is an elegant way to obtain the envelope of an oscillation function explained here http://mathematica.stackexchange.com/a/27854/15966 My question is how to modify the code below so I can fit ...
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1answer
133 views

Using a LocatorPane

I have a network of a power grid where the edge are the power lines and the vertices are loads or generators. I was wondering how I can import an image into Mathematica to derive some sort of ...
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votes
1answer
87 views

How to produce functions [closed]

I want to produce n functions. For example, assume that by giving n=3, 3 definite integrals will be created, like the following: ...
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1answer
254 views

Mathematica Implementation of Householder’s Method

I typed the Householder code in this paper, which starts on page 7. The code is: ...
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1answer
181 views

Defining a new matrix product of matrix function [closed]

Suppose I have two matrices A, B, whose entries are functions of x. Suppose they are 2*2. In the product, each entry is of the form $\sum_k A_ik B_kj$. There are two summands corresponding to k=1,k=2. ...
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votes
1answer
356 views

Heat Transfer equation by numerical methods

I want to solve the following heat conduction equation using numerical methods: D[u[x, t], t] -alpha*D[u[x, t], {x, 2}] == 0 u[x, 0] == 1/(1 + x^2)^0.25, u[-10, t] == u[10, t] == 0, ...
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votes
1answer
757 views

Evaluate function of two variables using nested Do loops

Is there a more efficient way of evaluating a function of two variables on a rectangular grid the the following nested Do loops? ...
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votes
1answer
253 views

A problem on generating convex hull

For example, I typed the following: ...
0
votes
1answer
102 views

Collecting roots of different equations and create a list

I solve two equations and have two solutions one by each equation. I want to create list of these roots. Could anyone please help me? Appreciate it. m02R150 = FindRoot[P1 == 0, {E1, 0.07, 0.1}] ...
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votes
2answers
133 views

How to obtain a smaller-sized output from Solve

I am solving a system of 15 simultaneous linear equations using Solve. On running the code, I get a message saying "A very large output was generated" with options ...
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votes
1answer
294 views

Problem with Eventlocator Method for NDSolve

I want to solve the ode and plot the solution v[x] for different values of parameter a where ...
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1answer
399 views

How to solve a problem in relative motion?

I have a project due tomorrow that I have been struggling with for a month. I am utterly stumped, any help would be appreciated. The problem is: There is a ferris wheel, 30m in radius, set 80m ...
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0answers
38 views

Long term growth model. Recurrence solution in NestList not behaving as expected compared to NDSolve

I'm trying to model the long term growth of a bioreactor according to monod kinetics: $ x'[t] = $$Qin \over V$ $( x_0-x[t]) + x[t]*\mu[t]\\$ $ s'[t] = $$Qin \over V$ $( s_0-s[t]) - x[t]$ $\mu[t] ...
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0answers
69 views

Can a whole Mathematica program be placed inside my functionMain? [on hold]

Consider this C code #include <stdio.h> int main() { printf("Hello world\n"); return 0; } A Mathematica equivalent could be ...
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votes
0answers
29 views

Retrieve rendered graphics via WSTP

I am planning on using Mathematica as calculation- and rendering backend for an application, i.e.: Call Mathematica via WSTP and by using EvaluatePacket have it ...
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votes
0answers
41 views

Trying to write a program to find an approximate harmonic function on a given graph using relation method

So given an undirected graph with two vertices that have fixed values assigned to them, a harmonic function is a function that assigns values to all other vertices such that the value assigned to each ...
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0answers
25 views

Iterating a model with 2nd order difference equations using Manipulate [duplicate]

I have a model including first and second order difference equations. It works for the case of first difference equation, which is below: ...
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votes
0answers
69 views

Stringing functions together

My professor introduced Mathematica to my class for the first time this week and gave us the following assignment. Also a disclosure that this is the first computer science class I have taken and the ...
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votes
0answers
53 views

Modifying Game of Life code so that the lattice can be seeded with life forms

I want to modify Game of Life code so that the lattice can be seeded with one or two new life forms like: ...
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votes
1answer
96 views

NDSolve with initial condition: initial conditions did not evaluate to an array of numbers of depth 1(for 1D) or 2 (for 2D) on spatial grid

I have the following naive code to solve a PDE in two spatial dimensions (x,y) with periodic boundary conditions: ...
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0answers
49 views

Define column types in a Dataset - Failure on append and Typesystem

I have a basic function that populates a Dataset according to user specified parameters. ...
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0answers
12 views

all does not work [duplicate]

Thanks blochwave for giving me a detailed answer, but I have already used all these methods and none of them has worked well, it is clearly written in mathematica "get help" file that the Timing[] and ...
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votes
0answers
37 views

How to simultaneously change variables shared by several functions?

I designed a fit program, the framework follows: a matrix build function: Q[a_,b_,c_,d_]; several matrix manipulate functions shared the variables {a,b,c,d} like this: ...
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votes
1answer
74 views

How can I use manipulate on multiple lists within a function?

So I have my N-Body Problem set up like so, and I can plot it in ListPointPlot3D, but I cannot figure out how to stick this into a manipulate function. ...
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0answers
80 views

I cannot pass any script to `math`, in a command line

I want to run some lines of Mathematica code by a command-line call for math. As a test, I save just the following code in a file ...
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0answers
50 views

Question about treillis structures

I have difficulties finding a command to plot multiple segments connected in nodes in Mathematica. Ultimately, my goal is to modelise something like this by entering nodes coordinates. Also, the ...
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0answers
111 views

Solving for a Transfer Matrix

I am currently working on a program that will solve a transfer matrix and extract several elements. Particularly, the transfer matrix is characterized by four elements in a ...
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votes
0answers
45 views

Find the maximum/ minimum of the function f(x,y,z) = x+2y+3z on the curve of intersection of the plane x-y+z = 1 and the cylinder x^2+y^2 = 1 [duplicate]

How to write the program for: Find the maximum/ minimum of the function f(x,y,z) = x+2y+3z on the curve of intersection of the plane ...
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votes
0answers
69 views

Using Animate/ListPointPlot3D on more than one list

I have a couple orbits defined which have been mapped into one array as shown: ...
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0answers
22 views

A question about conditional replacement [duplicate]

{g[x, y, z], h[x, y], f[]} /. (f_[t___] /; f != List) :> Plus[t] Why is the output of this expression ...
0
votes
0answers
30 views

what's the difference between CreateKernelLink() and CreateKernelLink(String Arg)?

I have a .NET program which will connect to MathKernel. When the program runs, there will be a icon of MathKernel on the taskbar. ...
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0answers
65 views

What is the meaning of //N in mathematica? [duplicate]

As the title says, What is the meaning of //N? i can't remember it.I tried looking in documentaion center, but it came up with nothing. Help appreciated.
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0answers
89 views

How do I perform the following numerical integration

I have the following integral to evaluate numerically: $$x(t) = \frac{1}{f(t)}\int_0^{t_b} t^m (t + n)^o \sin(pt) \mathrm{d}t \quad m,n,o,p \in \mathbb{R}$$ ...
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0answers
283 views

Converting a matlab program into Mathematica 10

I sought help from this entry at Calling MATLAB from Mathematica to see if I could CONVERT a mathlab program which simulates polymer dynamics that is provided at the download section at ...
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0answers
44 views

Path must include /TypeSystemLoader.m?

I have encountered a number of odd issues using the Wolfram Workbench 3.0 Debugger. Whenever I try to step into a Switch[] statement, I get the following error message: "Problem Occurred - Debug ...