Questions about optimizing code for faster results, or how to do faster computations.
23
votes
4answers
853 views
What is the fastest way to count square-free words?
Background
A word is a string of letters in an alphabet. A square-free word has no adjacent repeating substring. For example, (in the ternary alphabet of {0,1,2}) the words 00, 012121, and 0212012021 ...
19
votes
2answers
563 views
How to quickly calculate intersections of filled curves?
I am trying to quickly calculate the intersection of polygons with more than 6,000 points. A compiled solution would be preferable.
Here is one example of the problem:
...
14
votes
2answers
378 views
How can I speed up the classic GA for graph coloring?
I'm trying to compute the chromatic number of this graph (which is 28):
g = Import@"http://www.info.univ-angers.fr/pub/porumbel/graphs/dsjc250.5.col";
My genetic ...
10
votes
1answer
357 views
Is there a simple example using OpenCLLink that shows performance advantages?
OpenCLLink allows Mathematica to use the OpenCL parallel computing language. I have done some tests on simple examples, but so far, the CPU regularly outperforms ...
9
votes
2answers
265 views
Fast Simulations with Compile
this post relates to another post that I didn't follow up propely. If I wanted to simulate
a system of stochastic proesses like the following, and loop over this run many many times
would writing the ...
7
votes
3answers
201 views
How can I efficiently check if a graph is unit distance?
A unit distance graph is a graph that is embeddable in the plane so that every edge has length 1.
...
6
votes
2answers
605 views
Convolution with interpolated function
I have some problems to calculate in reasonable speed the convolution of an interpolated function with a Gauss function.
I have here (ExampleData.txt, alternate Pastebin link) data which I ...
6
votes
2answers
209 views
Use of Cellular Automaton or Discrete Convolution to calculate Potts Energy of a 2D Matrix
In a project of Monte Carlo Modelling of Grain Growth (Link) one of the most costly subroutines is the calculation of the Potts-Energy of an Monte Carlo Grid cell by comparing the center cell value ...
6
votes
3answers
286 views
Why is AstronomicalData so slow?
I'm having trouble getting some pretty simple functions using AstronomicalData to perform at anywhere near the speed I need them to.
For example, I have many ...
5
votes
1answer
128 views
Random number generation with specific distribution
I am writing a program for solving the shortest path in travelling salesman problem, with a twist that there are multiple salesmen who partition the cities among themselves, thus creating two part ...
4
votes
1answer
505 views
Improving NDSolve speed for heavily stiff problems
Having looked around the intergoogles and Mathematica.SE, I thought I'd pose a question with a minimum working example.
Here is the situation I am trying to improve:
I am solving a 4th order non ...
3
votes
4answers
163 views
Remove linear trend from data
I have a large data set with 150k lines and two data columns. I noticed that there is a linear trend, which I want to remove. So, I do the following:
first fit with a linear model
...
3
votes
2answers
141 views
How to speed up drawing a tangent plane?
I have this code to produce an interactive visualization of a tangent plane to a function:
...
2
votes
1answer
146 views
symbolic integration of a definite integral, how to speed up
I am wondering what are the general tips & hints for speeding up symbolic integration. As far as I understand, it solely depends on the form a function is represented before it is processed by ...
2
votes
1answer
112 views
EmpiricalDistribution for Gini Coefficient Runs Slow
I am repurposing code that I found in this blog post (http://datavoreconsulting.com/sports/gini-coefficients-and-the-olympic-medal-race/) to generate the Gini coefficient for other data sets I am ...
2
votes
1answer
169 views
Why is LogLogPlot[] slower than Plot[]?
I notice that LogLogPlot runs quite bit more slowly than ordinary Plot. For example, consider the following two blocks of code ...
2
votes
0answers
120 views
Project Euler (memory and speed issues)
Let n be a positive integer. An integer triple (a, b, c) is called a factorisation triple of n if:
1 ≤ a ≤ b ≤ c
a·b·c = n.
Define f(n) to be a + b + c for the factorisation triple (a, b, c) of n ...
1
vote
2answers
90 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 ...
1
vote
1answer
110 views
Speeding up code by avoiding repeated evaluation of a function
I want to speed up my code and I have two ideas, but I don't know how I can implement them.
Here is a little part of my code, which I want to improve:
...
1
vote
0answers
78 views
Performance in parameter estimation from ParametricNDSolve using varied initial conditions
I have 250 data points from a timecourse exeriment in a list, with columns specifying (1) time, (2-4) initial conditions, (5) absorbance reading. I want to fit 4 parameters (k1, k2, k3, k4) in a DAE ...
1
vote
0answers
297 views
Speed up Numerical Integration
EDIT:
I need to evaluate a very complicated multi-dimensional Integral. The dimension of the Integral depends on a variable j. Let's make my point clear with the ...
0
votes
1answer
87 views
Alleviating a bottleneck involving a function call with symbolic derivatives
I have a bottleneck problem involving a function call with symbolic derivatives.
I don't have much experience with Mathematica (or any dynamic language) and I'm certain that the way I've set this up ...
