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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4
votes
2answers
108 views

How would I programmatically add a row to a Dataset?

I would like to use a Dataset to track the process of a lengthy calculation over a large volume of material. Dataset appeals to me because of the power of the queries and it also looks like it may ...
0
votes
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 ...
2
votes
1answer
122 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 ...
0
votes
1answer
127 views

Finding CPU time of more than one expressions

I want to find the computational time (CPU time) of my code. When I use TimeUsed or Timing commands they give the CPU time of ...
0
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: ...
0
votes
1answer
81 views

InterpolatingFunction used to work with mathematic 7 but not working with mathematica 10

This code is used to work perfectly with Mathematica 7 and now it is not working with Mathematica 10. Any help is appreciated. CL05 = InterpolatingFunction[{{0.5, 11.99999999999999}}, {1, ...
7
votes
3answers
269 views

Interactively inspecting parts of an object

There have been times when I want to find the structure of an object in order to extract some part of it. For example, extracting the x and y coordinates from a Graphics object generated by Plot. I ...
0
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. ...
7
votes
2answers
329 views

How to get short definition of all built in Mathematica Functions?

The first post in "Mathematica Weekly Newsletter - Tuesday, December 30, 2014" really attracted my attention as I was always looking for a complete list of built in Mathematica functions with short ...
4
votes
1answer
204 views

A problem about Steffensen method

Two days ago,I asked a question about bisection algorithm. Thanks for Michael E2 giving me a good solution My algorithm 1, I use the bisection algorithm to generate a initial value that contain a ...
5
votes
2answers
301 views

Implement the Bisection algorithm elegantly and easily

Description: Rencently, I have finished my course Numerical Analysis, so I'd like to implement many algorithm that I have learned from that course.By this practice, I hope that I can improve my ...
0
votes
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 ...
1
vote
2answers
71 views

Subroutine execution repetition

I like to write second and third lines repeated operation only once as a separate module with some Name. In each main program line a set of different set boundary conditions data is given,Name invoked ...
0
votes
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, ...
13
votes
11answers
1k views

Divide all but the maximal element in a list by 10?

I have a list of numerical data, and I want to write a program that will keep the maximum as it is, but reduce the rest by certain factor (such as 10). For example: ...
4
votes
0answers
124 views

Can I define an axiomatic (Boolean algebra) system and prove theorems using Mathematica?

The general question is Can I define an axiomatic system and prove theorems using Mathematica? The more concrete one is about Boolean algebra. I consider this axiomatic Boolean algebra system ...
1
vote
1answer
76 views

RandomVariate form a Specific Distribution with Restrictions

There are a lot of questions about generating random numbers form both uni-variate and bi-variate distributions. Mathematica has a lot of built in distributions for that purpose. However, I could not ...
1
vote
1answer
250 views

Millionaire quiz in mathematica

so here's the deal. I'm trying to write a millionare quiz in Mathematica. Now, this has been already done in other coding languages, specifically I've seen it done in C here: ...
2
votes
5answers
124 views

GatherBy based on condition imposed on index variable

Excuse me. This might be user specific question but I need your help. I have an indexed data, where positive integers are used for indexing data. I am trying to group data putting condition on index ...
3
votes
1answer
255 views

A bug fix to mathematica 10.0.1.0

There is a bug in the Wolfram Symbolic Transfer Protocol Development in C (Windows). I described it in the next answer by myself, from which I summarize: One cannot successfully compile the ...
0
votes
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 ...
3
votes
3answers
150 views

What is shorthand way of Reap list that may be empty because of zero Sow

Sometimes because of conditionals, you cannot guarantee that Sow will be called at least once. Reap[Sow[1]][[2,1]] results in ...
8
votes
1answer
130 views

How to assemble and disassemble a function into steps

I've watched many programmers (both novice and expert) write functions in Mathematica and have observed a common behavioral pattern. This pattern has many elements that would be automated and thus ...
2
votes
1answer
64 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 ...
8
votes
2answers
311 views

Get rational and irrational parts

Consider an expression of the form $a + b \sqrt{2}$, where $a,b \in \mathbb{Q}$. How can I extract $b$ (or equivalently $a$) from this expression?
19
votes
0answers
304 views

How to perform document classification (i.e. extracting topics from text)?

I need to build a multi-label text classifier. There are a bunch of techniques for doing this, and it's called automatic document classification. I'm trying to use the EM technique (expectation ...
2
votes
1answer
121 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 ...
0
votes
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 ...
0
votes
1answer
44 views

Elegant ways of solving this file batching task

There are a batch of data files in a folder (dir = "D:\\Documents\\datadir"), each of which consists of a list of data items, one per line. Each data item is a pair ...
0
votes
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 ...
-1
votes
1answer
37 views

Finding the number that gives remainder equal to 0 [closed]

Hi i'm not english so I'll try to explain this as good as I can . If we have for example 250 : 5 = 50 , remainder 0 let's say I don't know the number i'm going to divide (because it is generated ...
2
votes
0answers
92 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: ...
0
votes
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 ...
4
votes
0answers
88 views

Implement a piecewise function elegantly and efficiently

Given that $$ g(x)= \begin{cases} max(x_{min},x-m) & 0.5x \leq max(x_{min},x-m) \\ 0.5x & max(x_{min},x-m)<0.5x<min(1,x+m) \\ min(1,x+m) & min(1,x+m)\leq 0.5x \end{cases}$$ ...
1
vote
2answers
76 views

How do you apply an algorithm individually to an array with many graphs

I have and array with many graphs to which I want to apply an algorithm (below) to each graph in an array that contains all my graphs. ...
7
votes
1answer
148 views

How to use RunProcess to import external function?

I have a functions written in an external language called GO. How can I quickly load them into the kernel for use as Mathematica functions? The two ways I've tried are with MathLink and LibraryLink ...
5
votes
1answer
92 views

How to implement kvo in Mathematica 10? [duplicate]

Key value coding and observing is something that other languages do well, like objective-c for instance. What's the best way to achieve something similar in Mathematica (if at all possible)? That is, ...
1
vote
2answers
51 views

How to get the outermost command evaluated first?

I have an expression like ToString[Stuff[...]]. I plan on having the Stuff[...] be manipulated as a string according to the output of other parts of the program. The problem is that Mathematica tries ...
1
vote
1answer
132 views

For loops in Mathematica [duplicate]

I'm actually the first time using loops in Mathematica. For example, I have: For[i = 1, i <= n, i++, For[j = 1, j <= n, j++, ....] How it is possible now ...
0
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 ...
6
votes
3answers
281 views

Calculating integral by Romberg Algorithm

In my "Numeric Anasyis" course, I learned the Romberg Alogrithm to calculate the numerical integral. The Romberg Alogrithm as shown below: $$ ...
0
votes
1answer
59 views

Symbol appears in multiple contexts when load two packages with unique function names

I have two packages "packageA" and "packageB". The function names across packageA and packageB are unique. No two functions have the same name. When I issue the ...
0
votes
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]]$^2$). ...
5
votes
1answer
306 views

How to solve this probability symbolically or numerically?

I am trying to calculate the following probability $$\mathbb{P} \big(\sum_{i=1}^{m} (A_i + S_i) \le L < \sum_{i=1}^{m+1} (A_i + S_i) \big)$$ where, $$A_i \sim \exp(\lambda), \quad S_i \sim ...
5
votes
0answers
218 views

How to download and combine S&P 500 stock prices

I want to download historical S&P 500 stock prices and combined them into one big file, having only one column of date referencing all stocks. Here is what I have do so far. ...
15
votes
1answer
309 views

Why does this line increase the consumed memory?

Probably this is a simple question, however I really don't understand this behavior in Mathematica. It particularly leads to a memory leak in a huge program I have to do processing of 3D images. I ...
0
votes
1answer
126 views

Optimizing Chi-square distance between two distribution

I want to program the chi-square between two distribution Xu and Vu with length N. This function is defined as below: Xu and Vu are real and positive. ...
4
votes
1answer
86 views

Slowdown of Flat attributed function

I was trying to write an associative function f using the attribute Flat. ...
1
vote
3answers
109 views

Creating a list of lists as a function of a list

I have a list of length n whose elements are all 1 and -1. For each -1 in the list i want to create a list with a -1 in the same spot and a 1 everywhere else. For example: A list like {-1, -1, 1} ...
0
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: ...