# Questions tagged [performance-tuning]

Questions on optimizing Mathematica code for higher performance. This may mean faster execution, lower memory usage or both. Not to be confused with mathematical optimization.

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### Determine the Number of Lines in a Text File

I have looked and looked but I do not see a simple efficient way to get Mathematica to return the number of lines in a text file? I thought about reading the file until it returned the EOF marker, ...
3k views

### Fastest way to measure Hamming distance of integers

I am looking for a fast and robust way to calculate the Hamming distance of integers. The Hamming distance of two integers is the number of matching bits in their binary representations. I expect that ...
1k views

### How can I speed up numerical integration of multidimensional integral?

I am numerically solving an integral equation that contains a double integral. I have managed to get a solution but it takes forever. I am wondering if there is a way to speed up numerical integration ...
335 views

### What ways are there to convert an Integer to a list of digits?

How can I convert an Integer to list of numbers? For example: 781049 ==> {7, 8, 1, 0, 4, 9} What are the possible ways of ...
820 views

### How to read off coefficients of tensor-like expression in a speedy way?

I am considering identities involving t[a, b, c, d, ...], where number of indices is fixed. t has the cyclic property so that <...
403 views

### Speeding up the non-negativity algorithm for multilinear function with interval probabilities?

The algorithm is a branch-and-bound algorithm that calculates the non-negativity of a multilinear function with interval probabilities. The lines 9-11 has an optimization that is explained on the 10-...
299 views

### Efficient code for building a big list

I would like replace the following code ...
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### Integral evaluation taking too long [closed]

When I try to evaluate the following integral, it runs for a much longer time than I think is should without producing a result. What might be the problem? Can anybody please point it out? ...
917 views

### Efficiently filling area with disks located at certain points

Starting from a set of points, I want to fill an area using disks. Each disk's center should be one of the points and the disks should not overlap. I've managed to write a function that, given a list ...
229 views

### Speed up plot of $\sum_{j\ge1} 2^{-j}(1-2^{-j})^{n-1}$

I'm a beginner at Mathematica. I would like to plot the following function: $${n\over2} \sum_{j\ge1} 2^{-j}(1-2^{-j})^{n-1}$$ However the following code is just too slow: ...
254 views

### Speeding up a simple simulation with random extractions

I wonder if anybody can help, I need a hand with a simple simulation I am writing with Mathematica (I am using version 8). Basically it creates a list (called l) with numbers from 1 to n and a random ...
134 views

### Is there documentation on the comparative performance of Mathematica functions? [duplicate]

Recently I have been solving some Project Euler problems. I find there are always several ways to do the same thing. For example, one could join two lists like this: ...
1k views

### Benchmarking expressions

It often happens that I'd like to know which of two or more alternative expressions (that should evaluate to the same value) is fastest. For example, below are three ways to define a function: ...
340 views

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### How can this DivisorSigma code be made fast?

Since Project Euler problems are now fair game for questions I have a question of my own. A certain problem* states: For a positive integer n, let σ2(n) be the sum of the squares of its divisors. ...
603 views

### Improve performance and style of solution to Project Euler #32

Since I'm fairly new to Mathematica, I'm trying to learn better ways to improve my coding skills so I've turned to Project Euler and this site to speed up my learning pace. Anyways, I was trying to ...
2k 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 ...
864 views

### Counting the population of integers

Suppose that myData is a list of sublists. Each sublist has a length of one or greater and contains any number of replicates of the integers 1, 2, 3, and 4. I ...
545 views

### Quick multiple selections from a list

What is the fastest way to make multiple selections from a list? Compiled methods included. For example, here are two methods for selecting a subset, compared:- ...
237 views

### Performance: Collapsing repeated contiguous rows & cols from a matrix

In this answer I needed to remove contiguous zero-valued cols and rows from a matrix, leaving only two of them in place, no matter what the original number was. I made up this code: ...