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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-1
votes
2answers
340 views

Performance of numerical optimization with triple integral [closed]

I'm trying to solve a numerical optimisation that looks something like this: ...
0
votes
2answers
175 views

Can I speed up the following plotting code?

I have the following Mathematica code. I do get the output graphs, but it takes like 12 seconds, on my computer. Longer still if I increase the value of n1. Are ...
3
votes
1answer
194 views

Parallelization of the stochastic Euler scheme

I wrote a simulation to approximate the law of a stochastic differential equation via a Monte Carlo method using the stochastic Euler scheme. Then I thought, it would be a good idea to speed up ...
0
votes
0answers
97 views

Inconsistent results in fits from NArgMin

EDIT: Just realized I had misspelled "inconsistent." I'm using version 7.0. I'm trying to fit a (noisy) data set to a large-order polynomial. (Just for context: there isn't a model for the ...
21
votes
1answer
367 views

A fast, robust DropWhile

For reasons that have never been entirely clear to me, Mathematica has had a built-in TakeWhile function since version 6.0, but has no equivalent ...
7
votes
1answer
958 views

Exporting a sequence of graphs as video efficiently

I have a sequence of graphs that are being created within Mathematica which I'm exporting to create an animated plot of the graph, as follows. ...
18
votes
1answer
282 views

Performance of compiled functions

I am trying to find the fastest way to calculate two values where both of them are sum of different expressions. I combine both calculations in one Sum[]. I'm ...
1
vote
0answers
260 views

Get path to end nodes in directed (partially cyclic) graph

I have a large directed graph containing small loops. I would like to extract all paths to all end nodes (no VertexOutComponent) with a given path length $n$. I ...
6
votes
2answers
126 views

DictionaryLookup very slow

I'm trying to plot, given a list of words, how many words belongs to each language. I'm using the following code: ...
4
votes
0answers
129 views

Efficient Generation of Subgraphs (or, unfriend a friend a day)

NB: If you're not interested in the back-story, you could simply jump forward to the code which I'm seeking to optimize. Also, I believe this code would only work for MMA 8.0 and above. My friends ...
3
votes
1answer
444 views

Efficient way to perform elementary integration step with NDSolve internal method

I'm trying to tweak the NDSolve function to perform one elementary integration step (using some explicitly selected stepping algorithm via ...
0
votes
2answers
257 views

Seeking faster method than using Table and If together [duplicate]

See the example below. Is there any way to make this execute much faster and still get the same output ? I have read Conditionals slower than operators? but it didn't really help me as I can't seem to ...
8
votes
1answer
941 views

Integration strategies for oscillatory multidimensional function

I am seeking to integrate a highly oscillatory, multidimensional function. I am currently using NIntegrate's QuasiMonteCarlo approach. However, this is time-consuming and, given my current resources, ...
5
votes
1answer
481 views

Reading in Huge Text Files

I would like to read in really large text files (about 2GB) into Mathematica. The structure of the file is such that the first row and the first column are text i.e strings. Rest is all numbers. Is it ...
2
votes
0answers
215 views
4
votes
1answer
501 views
1
vote
1answer
155 views

Improving the plotting time of a very complicated expression

The quatity $R$ is defined by a complicated expression in terms of $a_1,a_2,\ldots,a_n$. Now each $a_i$ is a function of $x$, $a_i(x)$. I would like to know what is the most efficient way to ...
1
vote
0answers
80 views

Is the TCPIP link type compressed?

Since I'm already piping a MathLink connection in a ssh tunnel (connect back is a pain!), I wonder if it makes sense to compress the data in the stream (ssh -C). As ...
5
votes
0answers
96 views

Faster way to perform SameQ[Reduce[…], Reduce[…]]

I'm have some expressions that I need to confirm the equality of. SameQ[Reduce[...], Reduce[...]] works like a charm for the more simple expressions, however when ...
2
votes
0answers
239 views

Speeding up a numerical constrained quadratic optimization

I'm trying to solve a quadratic optimization problem in 35 variables, $\vec{α} = \left< α_1, \ldots, α_{35}\right>$: $$ \begin{aligned} &\operatorname*{maximize}_\vec{α}&&1.0\cdot ...
9
votes
2answers
134 views
2
votes
3answers
361 views

Using ImageTransformation[] with a lookup table

I need to transform images by ImageTransformation in a time critical application. Therefore I precalculate a lookup table lut of ...
12
votes
4answers
509 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 ...
1
vote
1answer
123 views

PDF on TransformedDistribution of two BinomialDistribution too slow

I'd been doing my own convolutions of distributions for some calculations, decided to use built-ins. With ...
0
votes
0answers
372 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 ...
9
votes
1answer
254 views

Creating a NearestFunction that returns an index

I use Nearest repeatedly for large data sets. For example pts = RandomReal[{-1, 1}, {1000, 3}]; Nearest[pts, {0, 0, 0}] I ...
3
votes
2answers
219 views

How to replace Do loops by Inner

I need to replace Do loops by something else because it takes forever with big programs. I have been hinted towards Inner, but ...
25
votes
3answers
895 views

Common subexpression from two expressions

I am working with some unpleasantly tedious polynomials, which need to be manipulated in various ways (integrate with respect to some variable, differentiate with respect to another). Since these ...
24
votes
4answers
1k 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 ...
8
votes
3answers
173 views

How can I use the overhang argument to Partition to avoid using PadLeft and PadRight here?

Say I have a list of values v = {v1, v2, v3, ... }. I need to partition these values to perform operations with a sliding window (think ...
2
votes
2answers
454 views

Mass Symbolic Manipulation with Subscripts? (from plaintext Input)

The simplest example of the change being sought is a greek letter, typed in as plaintext nu, and its may be replaced by the symbol, ν: expr = 3nu*kx*ky+ ...
3
votes
1answer
126 views

Optimizing a simple calculus using a list of matrices - Repeated dot product between a vector and a list of matrices [closed]

I want to make the following operation : $$ \begin{bmatrix} \dot q_1\\\dot q_2 \end{bmatrix} + \begin{bmatrix} \begin{bmatrix} q_1 & q_2 \end{bmatrix} \mathbf A_1 \begin{bmatrix} q_1\\ q_2 ...
15
votes
2answers
2k views

Fast Spherical Linear Interpolation of list of quaternions

An accurate way to interpolate between two quaternions is to use Spherical Linear Interpolation (Slerp) because it preserves the unit length, whereas straightforward linear interpolation does not, as ...
4
votes
4answers
615 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 ...
4
votes
1answer
150 views

Why is this code in functional style is slower than procedural style?

I know that in Mathematica a functional programming style is often more efficient than procedural style programming using For loops. But the code shown below seems ...
5
votes
0answers
273 views

Parallelizing is much slower than single kernel evaluation?

Starting with a vector of matrices, tVec, I would like to parallelize the multiplication of each element with the same matrix ...
7
votes
2answers
267 views

How can this AbsoluteTime call be made faster?

I need to convert tons of date strings into absolute times. This generates an example data set of 10,000 strings: ...
1
vote
1answer
341 views

how to reduce the time to calculate triple integral

i want to evaluate the following integral, but it takes 15 min to do it. i must reduce the time to calculate it, i have to do a table and create a graph, but takes too long. anyone have an idea ? ...
5
votes
1answer
527 views

Montgomery Modular Exponentiation

I'm trying to write a Montgomery exponentiation based on this which can compete with Mathematica PowerMod. We know that PowerMod ...
1
vote
2answers
398 views

Import large amount of data with time stamps

I have a large data file (150 000 lines) which I want to import in Mathematica. The first few lines look like this ...
2
votes
0answers
114 views

Significant platform-dependent efficiency when importing data?

I'm curious, as I understand that answer this way: If you are using a Linux derivative or something like cygwin on Windows, then this is an efficient solution for reading only the third field ...
2
votes
2answers
1k views

Importing several huge files with headers & footers

having here several files in ASCII format http://ge.tt/91rv0Jf/v/0 I want to import, while removing headers and footers and then join the several lists. ...
4
votes
2answers
493 views

Efficient drawing of convex polyhedron given a set of points [duplicate]

I have a set of points in the 3D space and I want to draw the bounding convex polyhedron of those points. A very naïve solution would be to draw a triangle between every three points: ...
17
votes
3answers
767 views

Select performance

I am fairly new to mathematica and working my way thru Paul Wellins book on Mathematica programming so experimenting with various language constructs. I was experimenting with ...
2
votes
1answer
154 views

How can I place gui controls inside Grid? [duplicate]

In all my apps, I am facing a problem about placing the Gui controls inside Grid. For this purpose, I wrote three functions. The first function, ...
0
votes
2answers
754 views

Fast Autocorrelation Computation

I want to compute the Autocorrelation Function (ACF) of a data table with $10^6$ entries. I know that there is a built-in function in Mathematica for that, but because I do not know how exactly it is ...
17
votes
1answer
1k views

Optimizing a Numerical Laplace Equation Solver

Laplace's Equation is an equation on a scalar in which, given the value of the scalar on the boundaries (the boundary conditions), one can determine the value of the scalar at any point in the region ...
7
votes
2answers
347 views

Solving variant of the knapsack/money-changing problem

I'm trying to solve a variant of the knapsack/changing money problem where I have a set of a few numbers and I'm trying to find the linear (integer) combinations of them which are close to a given ...
17
votes
2answers
1k 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 ...