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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12
votes
2answers
361 views

Listing subgraphs of G isomorphic to SubG

If I have an undirected graph G, how could I write a function in Mathematica to obtain a list of subgraphs of G that are isomorphic to some other undirected graph SubG? I'd like to learn how to ...
12
votes
3answers
1k views

Big-Oh Notation

Is there a way to have Mathematica understand Big-Oh notation? For example, I want something like: MinBigOh[...] where ...
11
votes
8answers
483 views

Any built-in function to generate successive sublists from a list?

Given lst = {a, b, c, d} I'd like to generate {{a}, {a, b}, {a, b, c}, {a, b, c, d}} but using built-in functions only, ...
11
votes
3answers
1k views

What is Mathematica's equivalent to MATLAB's filter function?

The MATLAB code filter(0.5,[1, -0.5], [1:10]) is equivalent to Rest@FoldList[(#1 + #2)/2. &, 0, Range[10]] I don't ...
11
votes
4answers
930 views

Pure Functions with Lists as arguments

Assuming I have two function: example 1: add[{x_, y_, z_}] := x + y - z add[{1, 3, 5}] If use pure function,I know I can write it as : ...
11
votes
4answers
2k views

How to modify function argument?

Usually in programming languages, function arguments are normal local variables, which can be modified. Is this not true in Mathematica? ...
11
votes
4answers
601 views

Reproducing Image Patterns with Mathematica

Surfing on the net I stared at this pattern. It´s a bamboo steam, and it´s awesome. I'm new to Mathematica so I'm a little lost, I'd like to try to reproduce this pattern, of course in a very ...
11
votes
4answers
557 views

How to write this without For loop

Suppose I have a few lists of numbers and want to exponentiate element-wise, then sum up everything into a polynomial. For example, if I have ...
11
votes
5answers
2k 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 ...
11
votes
3answers
2k views

Programmatically generate packages from notebook files?

Currently, there are two ways I know of to generate a package (.m) file from a notebook file; one is to set the AutoGeneratedPackage option in the Option Inspector, ...
11
votes
1answer
1k views

Use Mathematica as a terminal

I love how notebooks work in Mathematica. You can edit code in real time and hit Ctrl+Shift to run it. Additionally you copy and paste different cells around to organize and test ideas. Search ...
11
votes
2answers
260 views

ShearingTransform and Dynamic

Background: I have a geometric transformation composed of a RotationTransform, ScalingTransform and ...
11
votes
2answers
613 views

Google Code Jam: Mountain View code review

After participating in Google Code Jam 2012 Round 2, it occurred to me that the Mountain View problem boiled down to solving a set of linear inequalities, which could be done in Mathematica. I've only ...
11
votes
3answers
174 views

Emulating Sequence with my own function

I just considered if/how one could implement Sequence in Mathematica if it were not predefined. It turned out that the following simple definition has in all my ...
11
votes
2answers
535 views

Dynamic Programming with delayed evaluation

By using dynamical programming, we can save intermediate steps for recursive relations, as in f[n_]:= f[n] = f[n-1] + f[n-2] However, this only stores ...
11
votes
1answer
347 views

Triggering actions when a variable is set

Some built-in variables trigger actions when their values are changed: ...
11
votes
1answer
317 views

Using Apply inside Compile

In this great answer a compiled version of the Nelder-Mead algorithm is presented. Since it works on arbitrary dimensions (i.e. arbitrary number of arguments), it has to use apply on the objective ...
11
votes
1answer
405 views

Generating Gelfand-Tsetlin patterns

I am doing some research on some combinatorial object called GT-patterns. They are generated from three parts of data. Two integer, partitions (sequences of weakly decreasing numbers), $\lambda = ...
11
votes
0answers
165 views

Can code optimize code?

Are there functions, programs or packages that deal with optimizing mathematica code i.e. re-writing ineffecive or convoluted code. -This question has haunted me since I joined SE. The background for ...
10
votes
4answers
286 views

Searching linked lists that contain lists?

Following the advice I've read here and other sites, I've been trying to use the Mathematica equivalent of a linked lists... ...
10
votes
5answers
506 views

How to find first list element that differs from average of N previous elements by more than a given amount?

Given a list of real numbers, I need to write a function that returns the value of the first element in the list that differs from the mean of the previous $N$ elements by greater than $P$ standard ...
10
votes
2answers
1k views

How do I automatically evaluate a cell when a notebook is opened?

I'm trying to put together a GUI in Mathematica and need to evaluate one cell to kick that off. Is there a way to automatically evaluate that cell when the notebook is opened? Here is an example of ...
10
votes
2answers
613 views

Finding all possible solutions to a math mind game

In the example below the letters shall be replaced by numbers. The numbers are from 1 to 9, and each letter has the same number ...
10
votes
5answers
323 views

For a given expression: if it appears, remove it, but if it is absent, add it

While reformatting Szabolcs's code from (42660) I noticed this interesting operation: ...
10
votes
3answers
323 views

How can I hold UpValues but evaluate other expressions?

Consider these definitions: own = "OwnValue"; down[_] = "DownValue"; sub[_][_] = "SubValue"; N[n] = 3.14; _[___, up, ___] ^= "UpValue"; The attribute ...
10
votes
3answers
504 views

How can I speed up SQL queries in Mathematica?

I have an application that queries a MySQL database many times for data. At the moment, Mathematica and MySQL are running on the same box and yet it takes over 1.6 seconds for the query to run and ...
10
votes
3answers
397 views

Generating Linear Extensions of a Partial Order

Given a set $S$ and a partial order $\prec$ over $S$, I'm looking for a way to "efficiently" generate a list of linear extensions of $\prec$. Suppose the partial order is given by a ...
10
votes
2answers
2k views

Pass function or formula as function parameter

I can write either Integrate[x^2, {x,0,3}] or f[x_] = x^2 Integrate[f[x],{x,0,3}] and get the same computation. Suppose I ...
10
votes
2answers
228 views

Why isn't Lookup treated like other symbols?

With Mathematica 10, I wanted to overload Lookup using TagSetDelayed, but it doesn't work. For instance, if I define two objects ...
10
votes
1answer
166 views

Are formal characters like \[FormalA] to be used differently than other symbols?

I noticed that Mathematica has a set of special 'Formal' characters such as \[FormalA], \[FormalB] , etc.. In the front end, it ...
10
votes
1answer
209 views

Is there a method to enumerate the keys/values of System`Utilities`HashTable

Lacking from the simple API of System`Utilities`HashTable is a method to enumerate the keys/values. ...
10
votes
1answer
601 views

Modifying a List in a function in place [duplicate]

An example will be most specific: func[list_, column_] := list[[All, column]] = Map[#*2 &, list[[All, column]]]; This throws errors. I want to avoid doing ...
10
votes
1answer
379 views

Abort not aborting

I have a relatively simple bit of code that looks like the following: ---some code here--- If[statement, Abort[]]; ---more code following--- However, while ...
10
votes
2answers
336 views

Visualizing several long lists of numerical information to see relative frequency

Mathematica has very powerful visualization techniques. However, I'm at a loss at how to best make the following chart readable. ...
10
votes
1answer
163 views

Figuring out how AbsoluteOptions works with Graphs

I am puzzled by how AbsoluteOptions works with Graph objects. I would have expected that one could use it to obtain all the ...
10
votes
0answers
283 views

Create a new infix operator [duplicate]

It is well known that the infix operator @@ is used as a short form of Apply. For example, both ...
9
votes
7answers
386 views

How to efficiently Append a result of an operation on each element of a list to itself

I'm looking for the best function to apply the product of the last two elements of sublist elements to each element: Example: ...
9
votes
4answers
411 views

When should I use Apply (or Function) and when @@ (or &)?

This is a rather general question, which I fail to answer myself. I guess it is mainly due to my insufficient knowledge of the precise terms. If I understand correctly, the following are equivalent: ...
9
votes
6answers
510 views

Best way to find permutation with specific total

Can anyone suggest a good way to find permutations of 12 digits, 0 to 4, totalling 24. I.e. two such permutations:- {2, 1, 4, 1, 2, 2, 2, 2, 2, 2, 1, 3} // Total ...
9
votes
5answers
1k views

Select/Delete with Sublist elements?

Probably easy and short question, I still didn't fully figure out how to easily select/delete sublists from a list. Example: tt = {{2, 4}, {4, 8}} I want to delete/select all the elements where ...
9
votes
3answers
651 views

Improve speed for calculating a recursive sequence

I want to calculate following recursive sequence: $\alpha_{0}=0,\\ \cos(\alpha_{i})=\cos(\alpha_{i-1})\cdot\cos(\beta_{i})+\sin(\alpha_{i-1})\cdot\sin(\beta_{i})\cdot\cos(\gamma_{i}).$ In ...
9
votes
5answers
452 views

Incrementing a number where each digit has a different base

Let's say I have a list, for instance {10,5,3}, indicating the bases for each digit of my 3-digit number. Using this basis, if I wanted to increment {8,4,1} a couple of times, here's what I would get: ...
9
votes
3answers
419 views

Dealing with nested options

OptionValue allows for recent versions of Mathematica (I think as from 7) to easily access optional parameters if they are explicitely given to a function or their default values otherwise. For big ...
9
votes
4answers
482 views

How to implement dual numbers in Mathematica?

I wonder how can I implement dual numbers in Mathematica, so that all functions work well with them (as with complex numbers). Particularly, for each function $f$, ...
9
votes
3answers
223 views
9
votes
2answers
179 views

How can I build an inline documentation utility?

I often have a large function to which I add inline comments, but then I can't see the forest for the trees. How can I make a tool that extracts the comments and tokens within them to generate an ...
9
votes
2answers
910 views

Implementation of smoothing splines function

I have some problems by writing a module for spline smoothing. Actually i am trying for about two weeks. My listing is here: ...
9
votes
4answers
879 views

Passing large list by reference

I have the following problem: I would like to control evaluation of a variable that points to a list. For example, frequently in the code I have functions of the form that are supposed to work on ...
9
votes
2answers
147 views

How to make TraditionalForm display the same in the Manipulate output as in a notebook?

I noticed that TraditionalForm does not display as nice in the Manipulate output as in normal notebook. Is there a way to make it look the same? Here is an example, ...
9
votes
2answers
1k 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. ...