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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0
votes
1answer
119 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 ...
4
votes
4answers
556 views

Skip other If conditions

I'm trying to write a code to "random" move in a matrix but it can't go to a certain position if it has a certain value (in this case I'm using the number 2). How do I make it to skip all other If ...
8
votes
1answer
105 views

CSS Selectors for Symbolic XML

Symbolic XML is a convenient way of managing XML in Mathematica, at least for casual use or small tasks. Here and elsewhere you can find examples of XML handling in Mathematica, including XSLT/XPath ...
2
votes
0answers
49 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; ...
0
votes
2answers
135 views
0
votes
0answers
35 views

Can the value of a variable be made to persist between front end sessions? [duplicate]

For example, say I create a notebook with a cell a = 5 + 2 and then I close Mathematica, reopen the notebook, enter a new cell ...
1
vote
0answers
114 views

Finding Values of All Nine Constants in q-hypergeometric Equation

I suspect that an identity of the form $$\sum_{j=-n}^{j=n}(-1)^jq^{j(5j+1)/2}=\sum_{r=0}^{n}f_{ar+bn+c}(-1)^{n-r}q^{(n-r)(dr+en+f)/2}\frac{(q;q)_{gr+hn+j}}{(q;q)_{n-r}}$$ for $a, \dots , j$ integer ...
1
vote
0answers
87 views

Whats Mathematica exactly is? [closed]

Is it a software to learn mathematics and programing? Or what? Sorry for my ignorance and my English. I'm not clear about what is.
0
votes
1answer
81 views

ParallelTable not firing

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0
votes
0answers
44 views

What is a good alternative to this numerical example taken from FindFit?

I am using MMA V9.0 What do you suggest for this numerical example? I am not getting good results trying to use my own procedure to find a "best" fit using the 1-norm. The 1-norm example for ...
14
votes
4answers
1k views

How to implement the Observer design pattern?

As a programmer with a history with procedural languages, the Observer design pattern inmediately springs to my mind when attacking certain class of problems, mostly UI/notifications related. A ...
3
votes
1answer
122 views

Why even try the semantic constraints, if expression can't match the pattern structure?

This result is unexpected: Trace[MatchQ[{7}, {_?NumberQ, __}], NumberQ] (* -> {{NumberQ[7], True}} *) Why evaluate ...
0
votes
1answer
132 views

Using Findroot within a loop

I am trying to get solution to an equation in a loop. The isolate equation works ...
4
votes
1answer
149 views

DynamicModule inconsistent behavior; was: DynamicModule persistent UI changes

Update: I'll restate the question in hopefully more terse and clearer terms. To illustrate the issue, run this and save the resulting notebook: ...
1
vote
4answers
119 views

How to count number of {True,True} outputs?

Do[Print[{x + y + z == 3, x + y > z}], {x, 1, 2, 1}, {y, 1, 2, 1}, {z, 1, 2, 1}] If I run this syntax I get a series of Outputs, I am trying to Count only the ...
5
votes
3answers
224 views

Split list of states by run lengths and discontinuous changes in state

I was asked to look into writing some simulation code for a user, where the simulation output (x) would oscillate between three possible states: ...
0
votes
0answers
74 views

How to save the results in an identical Excel file (.xls) in each iteration of a Do loop

Assume the following code (Below code is just an example to clearly illustrate my problem): ...
0
votes
0answers
92 views

Mean Squared Deviation for Population Data

I've been using the Lotka-Volterra equation to estimate population sizes and need to find the MAD (mean absolute deviation), MSD (mean squared deviation) and mape (mean absolute percentage error) for ...
9
votes
2answers
975 views

Is it possible to create iOS apps with Mathematica?

I am fairly new to Mathematica and don't have much experience with other programming languages, but I can already see that Mathematica and the Wolfram language are far easier to use than most others. ...
2
votes
0answers
48 views

What is “ (Dialog) Input [ ] := ” after evaluating a cell?

I have done a time-consuming run and calculation. After many hours ( about 7 hours!), the black color which shows that the cell is evaluating, turn into gray and a strange text appears like this : ...
1
vote
1answer
88 views

Scope of variables within a Manipulate expression [duplicate]

I have a problem in defining the local variables. I have this code: ...
20
votes
4answers
948 views

Detecting patterns of black and white stones on a 2D board

I'm writing a program to play a game of Pente, and I'm struggling with the following question: What's the best way to detect patterns on a two-dimensional board? For example, in Pente a pair of ...
-1
votes
1answer
44 views

How to loop in reverse order?(e.g. for i from 10 to 1) [closed]

I have a list F = {382.856, 638.53, 915.482, 1192.44, 1469.39, 1746.34, 2023.29, 2181.91} And I want to use it to calculate V: I think it should be something ...
0
votes
0answers
92 views

Issue with Set function

Tables often come with column headers. Indexing the columns with the header is a natural thing to do. Although a proper dictionary is the usual solution in such a case, I find it often practical and ...
0
votes
0answers
100 views

A problem with functions and Infinite expression 1/0 encountering

Following code (function) makes integrals and then replace f[x] with Cos functions and calculate the definite parametric ...
0
votes
1answer
105 views

A problem with set values

The following code is just an example to clearly explain my problem. Assume that : ...
0
votes
1answer
85 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: ...
0
votes
1answer
132 views

Mathematica Implementation of Householder’s Method

I typed the Householder code in this paper, which starts on page 7. The code is: ...
2
votes
0answers
53 views

Can BreadthFirstScan be modified?

I would like to obtain a "slick" implementation of A*-search algorithm on Graph objects, using the built-in BreadthFirstScan (if that is possible at all). I noticed that BreadthFirstScan is static in ...
1
vote
1answer
105 views

Help to solve the equation with RungeKutta method [closed]

I need to solve this equation. v'[t] + v[t] == 1/(1 + Exp[-v[t]]) I tried to solve it using RungeKutta method described in Wolfram ...
7
votes
1answer
102 views

Equivalence under common permutations

I have lists which consists of sublists of equal length. The outer list is regarded as a multiset (that is, permutations of the sublists don't matter, but repetitions do), but the order in the ...
0
votes
0answers
25 views

Does RuleDelayed work inside MessageName?

using : Mathematica 9.0.1.0 Hello ! Does RuleDelayed work inside MessageName ? This code: ...
1
vote
1answer
115 views

How to replace a list with the result list after each iteration [closed]

I have some initial values such as L1 list: L1={10,20,30,40,50}; I want to use the L1 ...
4
votes
1answer
91 views

How to set the position of the palette when use CreatePalette[]

When using CreatePalette[], the palette created always shows up on the upper left corner. Is there a way to make it show up at the center of the screen, just like ...
3
votes
0answers
118 views

How to restrict the mouse cursor to stay within a box?

I'm trying to use Mathematica to write small games, and I find that it would help to restrict the player's mouse into the game window (just like other games do). Is there any way to achieve this? ...
0
votes
1answer
54 views

Problem with Label in a Do loop, “nolabel” [closed]

Can someone tell me why this code doesn't work and how to fix it ? Thanks. ...
1
vote
3answers
175 views

How to update a list in a function in each iteration

There is a list with numbers 1 to 8 ( p1 ) and another list (j) which contains 4 numbers which shows different 4 positions of ...
1
vote
3answers
181 views

How to replace identical positions in two different lists

Assume that I have two lists like : list1={1,2,3,4,5}; list2={a,b,c,d,e}; I want to replace some elements from list1 into ...
-1
votes
1answer
90 views

Transformation of a simple logic statement

I'm designing a logic circuit and I was wondering if the following two things are equivalent: (x <= y) and (x < (y + 1)) I can't think of any set of numbers that would make these two things ...
0
votes
1answer
50 views

How to put some values from a list into a function in a Do loop

I want to program a code in MATHEMATICA in order to calculate some values in different iteration. For example, assume this list: list={1,2,3,4,5} Now assume that ...
1
vote
2answers
77 views

Avoid making repeated Random Integer in different iterations

Assume following code : Do[ i1 = RandomInteger[{1, 5}]; i2 = RandomInteger[{1, 5}]; While[i1 == i2, i2 = RandomInteger[{1, 5}]] , {k, 1, 4}];` This ...
0
votes
1answer
146 views

Defining a new matrix product of matrix function

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. ...
1
vote
1answer
104 views

Requesting explanation of FitModel code

I am struggling with understanding the code given in this original post I understand how the tests are conducted, both of them. However, I do not understand this part: ...
0
votes
1answer
236 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, ...
11
votes
5answers
1k views

What is the fastest way to extract a substring from a huge string?

I develop an algorithm to find the most common substrings of a given length n up to a certain distance l in front of a pattern p in a huge sequence S. E.g. I want to find the most common hexamers ...
0
votes
2answers
96 views

Finding lags of time series with `Do`

I have generated two time series, S[t] and P[t] as follows: ...
1
vote
1answer
64 views

Hide MathKernel Tab on Taskbar when using C++ [duplicate]

I am connecting to MathKernel.exe using C++ via MathLink on Windows. Hence, to create the link, this is what I use: ...
13
votes
2answers
413 views

Most influential and/or disrupting features introduced with new versions of Mathematica

This is something that has been bugging me for ages. With every upgrade, Mathematica has added new functionalities and amendend some of its bugs. In the process, though, some older functionality has ...
1
vote
1answer
431 views

Euler's method for system of differential equation

I need to program Euler's method to solve a system of two diffferential equations of first order. Fist, I have programmed the Euler's method for just one differential equation: ...
1
vote
0answers
81 views

Read expression from Mathematica via Mathlink C++

This is a simple C++ program to send an expression to the_Mathematica_ Kernel and get its response. ...