# Tagged Questions

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.

854 views

### How to correct my code for solving the Josephus problem?

Problem Decription Recently, I have been reading the book Schaum's Outline of Mathematica (2nd Edition), where I encounted the problem: Flavius Josephus was a Jewish historian of the first ...
928 views

### Implementing a function which generalizes the merging step in merge sort

One of the key steps in merge sort is the merging step. Given two sorted lists sorted1={2,6,10,13,16,17,19}; sorted2={1,3,4,5,7,8,9,11,12,14,15,18,20}; of ...
912 views

### Mathematica usage (success stories) for financial back-ends

I've been working for about 5 years in Java, developing financial back-offices (web-services, business logic, report generation etc.). I think Mathematica is very suitable for such calculations and ...
1k views

### Is there a Mathematica/Lisp link?

I'd like to start learning Lisp as it sometimes leads to interesting answers on this site with concepts borrowed from this language, so I'm curious. As I already spend most of my programming time in ...
759 views

### How can I improve my code for drawing a tree?

This code draws a tree, but it's not in the functional style. ...
3k 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, ...
370 views

### How to make use of NumericQ[x] = True (and use it safely)?

Basic Issue: I'm trying to understand the proper use of NumericQ's "magical" capabilities. Please consider the examples below. Actual question and some links are ...
385 views

### How to programmatically ask if Mathematica is running as an Administrator

To avoid execution problems in a program I need to know if Mathematica has been "Run as administrator". What would be the cleanest way to programmatically getting this information?
208 views

864 views

### Question about designing a particular data structure

Background: I store polygons with a color assigned at the face level. In some occasions I want to use vertex colors but I want to store data efficiently, i.e. don't want to duplicate data to the ...
673 views

### rule-based implementation of an algorithm

When I first started learning about rule-based programming with Mathematica, I tried to translate this algorithm for computing the convex hull of a set of 2-D points in $O(n \log(n))$ time, to use ...
543 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 ...
176 views

### How to make a dynamic nested menu?

There is no dynamic controller that can represent a hierarchical menu structure: ActionMenu can only handle flat action lists. Thanks to Kuba, we know a lot about <...
378 views

### Tips to move from functional programming to GUI-based applications

Even though this forum has some questions related to Mathematica programming tips I think that we still don't have specific help for those who want to learn to efficiently create GUIs in Mathematica. ...
503 views

### Generating a matrix using sublists A and B n times

I want to write a function that generates a square matrix from sublists. My sublists are a = Range[0, x, 0.5]; b = Range[0.25, x + 0.25, 0.5]; Suppose x=2, then I ...
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: ...
647 views

### How can I generate a nested array like this one?

Well, this is how the array looks like: I came up with this code: n = 10; Nest[ArrayPad[#, 1, 1 - #[[1, 1]]] &, {{1}}, n] /. {1 -> "*"} Any better ...
775 views

### Does AbsoluteTiming slow the evaluation time?

I've started using AbsoluteTiming to discriminate between similar function constructs, but I sometimes feel like it takes substantially more time to evaluate a ...
1k 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 : ...
416 views

### Unencoding encoded URLs in a function

Is there a built-in function for decoding encoded URLs in Mathematica? I would like to convert an encoded URL, for example ...
687 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 ...
1k views

### Splitting up delimited data in lists

One task that I frequently find myself doing in Mathematica is splitting lists into lists of sublists, using specific elements to define the break-points. This is particularly useful with imported ...
1k views

### Mathematica Application in Real Life

As an 'user'-level in Mathematica, I mainly use built-in Mathematica function and benefit Mathematica as a mathematical tool-box for my specific scientific problem. My level is not yet programmer-...
716 views

510 views

### Collatz optimization

I'm VERY new to Mathematica programming (and by new I mean two days), and was solving Project Euler question 12, which states: Which starting number, under one million, produces the longest [...
528 views

### Can you recommend an efficient method for finding the least integer satisfying my inequality?

I tried find the minimum make $\frac{1}{2}+\frac{1}{2+\sqrt{2}}+\frac{1}{3 +\sqrt{3}}+...+\frac{1}{n+\sqrt{n}}>15$ Following code is so slow when I use condition ...
6k 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 ...
283 views

### ShearingTransform and Dynamic

Background: I have a geometric transformation composed of a RotationTransform, ScalingTransform and ...
1k views

### Problem with Fourier coefficients

I have just started using Mathematica with v9.0. I am trying to follow a computation from a book on Fourier series with the function $f(x)=x$ on the interval $-\pi < x < \pi$. Here is the code ...
550 views

### Evaluation indicator for a notebook

I have a GUI with a number of TabView and other Manipulate controls. Sometimes clicking from one tab view to the other can take ...
538 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 ...
954 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 (...
1k views

### Suppressing negative roots in Mathematica

Problem Using Mathematica's Solve operator can sometimes lead to an output involving a positive and negative root (say when solving for a variable such as ...
256 views

### How to implement a more efficient inverse triangular recursion?

Consider the following inverse triangular formula \left( \begin{array}{ccccc} & & & & N_{i-p,p}\left(u_0\right) \\ & & N_{i-2,2}\left(u_0\right) & & ...
751 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 ...
266 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 ...
3k 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. ...
121 views

### How to remove a LocalSymbol (or CloudSymbol)?

In version 10.2 LocalSymbol can be used to create a persistent store of a variable. Once this is created I don't see a method to remove it. How are are they ...
434 views

### Triggering actions when a variable is set

Some built-in variables trigger actions when their values are changed: ...
366 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 ...
270 views

### How to add AccuracyGoal and PrecisionGoal options in a numerical function?

There are many built-in functions that contain AccuracyGoal, PrecisionGoal and ...
2k views

### Multi-objective genetic algorithm in Mathematica?

Is there any implementation of a multi-objective genetic algorithm for Mathematica?
1k views

### Big-Oh Notation

Is there a way to have Mathematica understand Big-Oh notation? For example, I want something like: MinBigOh[...] where ...
454 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: ...
2k views

### Beautiful dance of the Earth and Venus around the sun

I have seen very nice dynamic graphics created by users of Ma. I would like to get help whether the following graphics can be created using Ma. I was not able to create the dynamic picture here. ...
1k views

### Morphing a “sheet of paper” into a torus

How can I visualize the standard topological "rubber-sheet" construction of a torus, that is, morphing a square into a torus? How can I start or are there any examples in the Mathematica ...
574 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 ...