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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23
votes
5answers
881 views

Can (compiled) matrix permanent evaluation be further sped-up?

Update III  Mathematica 10.2.0 now ships with a predefined System`Permanent function, which the PermanentCode package ...
0
votes
1answer
227 views

How to improve the performance of this code

I have implemented a code in Mathematica 9 to simulate a scattering problem, and I got really disappointed about its performance when compared to Matlab. Since I am a newbie in Mathematica, would ...
0
votes
2answers
241 views

Modified ListPlot, how to speed it up

I use Mathematica almost every day for several jobs (computations, graphics, etc.). I admit that this software contains much more options (capabilities) than one user may need. Well, not always since ...
0
votes
0answers
72 views

Can you set up a remote kernel for computation and a local kernel for predictive interface?

I am able to launch remote kernels from my Windows box to our Linux cluster that has the data I need and the capacity to run analysis (numerous & speedy cores, spacious memory, etc.). Works ...
29
votes
1answer
337 views

Why is multidimensional Reverse slow?

Bug introduced in 6.0 or earlier and persisting through 10.3.1 I have found that multidimensional Reverse is ~10 times slower than exact ...
6
votes
2answers
139 views

Integrate perfomance

I have a notebook in Mathematica 4. I'm trying to convert it to use in Mathematica 9. One of the problem is the long computation of definite integral in the new version of Mathematica. Here's the ...
9
votes
2answers
260 views

Additive SparseArray Assembly

The goal is to assemble a SparseArray in an additive fashion. Let us assume we have a large List of indices (some will be ...
1
vote
1answer
95 views

Plotting a sum as a function of its upper bound

Apologies if this is easy to find in the documentation, but is there a quick way of doing the following up to any given 'n'? ...
5
votes
2answers
194 views

Reading non-tabular data with NaN-s from file

A NaN stands for an entry that is not a number/undefined/missing/infinite/etc. On my machine the C code printf("%f", 0/0.) produces ...
4
votes
1answer
210 views

Calculate the covariance of a large matrix

I have to compute the covariance of 50 very large integer matrices (2500x2000 elements). However, according to my estimation this will take around 10 days. Do you have any ideas how to speed things ...
2
votes
2answers
129 views

Definite Integral. Perfomance problem

I have a notebook in Mathematica 4. I'm trying to convert it to use in Mathematica 9. One of the problem is the long computation of definite integral. In Mathematica 4 the result of the following code ...
2
votes
3answers
179 views

Efficient matrix multiplication

I have a list of vectors vecs = {vec1, vec2, ..., vecN} where veci is a list with length $N$. Now I have a matrix $N\times N$ ...
3
votes
2answers
231 views

My code for solving n queens problem Compile Failed

I want to make my code for solving n-queens problem faster, but it seems that MapIndexed can't be compiled. Mathematica return CompiledFunction::cfse: Compiled ...
2
votes
1answer
122 views

Putting values into a grid after iteration process

I'm developing a model of thermodynamic cycle in Mathematica. I wrote several functions, applied them to a list containing starting values and iterated, for the model to converge. ...
8
votes
4answers
397 views

Slow plotting of trigonometric functions

I have two sets of solutions for a and b. I'm plotting solution only if it is positive for both ...
3
votes
1answer
265 views

How could I improve this Central Limit Theorem demonstration speed- and content-wise?

My purpose is to demonstrate the Central Limit theorem by assuming two custom distributions, taking some random samples, calculating their means and ploting the results. Ideally, the histograms should ...
6
votes
0answers
121 views

Slow NIntegrate over complicated domains (sometimes)

This is no longer a problem with Mathematica 10.* where I can use regions to do the integrations Overview I have a very large matrix I need to calculate where each element requires the integration ...
4
votes
5answers
293 views

Can I generate a “piecewise” list from a list in a fast and elegant way?

Suppose we have a number list a: n = 1000000; a = RandomReal[{0, 1}, {n}]; We want to generate a list ...
3
votes
0answers
143 views
5
votes
2answers
200 views

how to improve efficiency when I want to classify a list according to certain laws

I have a function that generates lists: f[n_] := Join @@ Permutations /@ PadLeft@IntegerPartitions[n]; For example f[3] ...
2
votes
1answer
663 views

Simulated Annealing InitialPoints option

I have a cost function that depends on 4 parameters: CostFunction[{tx,ty,tz,ox}]. I used NMinimize[] function with ...
7
votes
1answer
383 views

Efficiently searching a list for the position of the closest number to a specified number

Searching by closest and position I wasn't able to find an answer—but found Nearest by guessing. Nearest, however, returns ...
4
votes
1answer
272 views

MapThread Alternatives

I want to add two matrices, the first one containing a 2D vector at each position the other one a list of 2D vectors. The 2D vector from the first matrix should be added to each of the 2D vectors at ...
4
votes
1answer
180 views

MapThread and Compile

After discovering that MapIndexed cannot be used with compile (see MapIndexed and Compile) I am now trying do implement similar functionality using a combination of ...
9
votes
1answer
720 views

Imposing a Periodic Boundary Condition in Nearest Neighbour Search

I am trying to find first nearest neighbour distributions of randomly dispersed point-like objects in an infinite system. To do this I make a finite sized box unit cell with a chosen concentration of ...
5
votes
0answers
87 views

Is there something like MaxProcessorUsed?

For standard procedures it is easy to test if the implementation is better or worse than other by using Timing etc. It does not help us with creating ...
3
votes
0answers
416 views

Taking real and imaginary parts of indexed functions and speeding up ComplexExpand

I am setting up a large system of ODEs and in order to use the IDA method (which is sig. faster for my system and thus attractive), I must split my equations into real and imaginary parts. I am ...
5
votes
1answer
149 views
10
votes
2answers
535 views

Why is ParallelMap way slower than Map

I recently tried to use ParallelMap instead of Map and to my surprise encountered that ...
0
votes
1answer
165 views

Better way to evaluate integral containing Boolean function

I am trying to compute the integral ...
0
votes
1answer
227 views

How to combine two usages of # into one and speed up the code?

I have a function num with two variables, matf and matg. How can I combine the last two lines of code below into one? The code is aimed to find out the maxiaml count bel when we give each $i3 = ...
4
votes
3answers
444 views

Improve the performance of solutions to Project Euler (#14)

Problem I have following code, when n<=10^5 it's not slow, but n>2*10^5 it's became very slow. I think maybe some temp value greater than 2^31-1, so make compile invalid. Could you give any idea ...
5
votes
2answers
180 views

How to optimize computing a product?

Problem description Write a function to caculate the formula My solutions Solution 1: ...
6
votes
1answer
985 views

Fastest way to do vector / matrix multiplication with constant matrix

Suppose we have a fixed n x n matrix, call it $B$. What is fastest way to evaluate $v^t B\;v$ over many different vectors $v$? Since $B$ is a constant matrix, does this allow the number of operations ...
0
votes
1answer
158 views

Efficiency problem with least square algorithm (Error in both variables)

I was informing myself about the least square algorithms with errors in x and y. I found this post and the top answer wasn't ...
5
votes
1answer
293 views

How to speed up multi-curve plotting?

The following example is a very simplified version of the problem I'm working with, though I hope it still captures the essentials. First, the definitions: ...
3
votes
1answer
170 views

Any way to speed up evaluation in an Animate?

I have a self-defined function which is fairly complicated and gives the analytical form. The result contains two independent variables. I use Animate to plot the ...
25
votes
5answers
708 views

Compiling ColorFunction for faster complex phase-amplitude plots

I have gotten into the habit of plotting complex-valued functions on a plane using a color-function along the lines of ...
7
votes
1answer
112 views

Why does Rescale performance vary significantly based on the real number values in a list?

I have a list of the form: testList = Table[{Flatten[RandomReal[{-200, 200}, {1, 2}], 1], RandomReal[{-200, 200}, {69, 2}]}, {i, 1, 100}]; And I would like to ...
0
votes
1answer
175 views

johansen test error in code

Cross-posted at the Wolfram community forum I have found this code on a forum, apparently it worked in a previous version of mathematica. Now when I run it, it keeps running for ages. I am not able ...
1
vote
1answer
91 views

Insert glyphs into a string using functional code

I asked this question few days ago: Replace For-loop with functional code Suppose I use strings instead of lists; for example a = ToString /@ {123123, 112233};` ...
5
votes
2answers
213 views

Parallelizing or optimizing a script for calculating the size of all pairwise intersections between collections of sets

I need to speed up or parallelize an operation that looks essentially like this: ...
4
votes
2answers
441 views

Quickly reducing the number of decimal digits for a set of real numbers

How can I quickly convert a number with $n$ decimal points to a number of with $m$ decimal points? Round works, however, it is slower than I would like. This ...
2
votes
2answers
249 views

Reducing quality of Graphics3D scene to improve performance?

ProteinData["SERPINA1", "MoleculePlot"] gives the detailed Graphics3D plot below. I'd like to make many small copies of this ...
6
votes
1answer
149 views

Why LinearModelFit is slower than NonlinearModelFit?

Why LinearModelFit is slower than NonlinearModelFit? ...
8
votes
2answers
247 views

How to reduce the number of operations needed to evaluate an expression? [duplicate]

For some numerical calculations in C++ I have, for example, this complicated expression to evaluate. Given as Mathematica input, in its original form it is ...
4
votes
3answers
472 views

SparseArray row operations

Given a large (very) sparse matrix, A, how can I efficiently "operate" on only the nonzeros in a given row? For example: For each row in A, generate a list of column indices that have a magnitude ...
3
votes
1answer
311 views

Manipulate executes expressions multiple times

I am using Manipulate for a rather intricate front end for data visualization. I was getting very sluggish performance and was able to boil the problem down to a ...
6
votes
2answers
563 views

Faster Eigenvalues with lower precision goal

I compute all eigenvalues of a large matrix, and I decide that the speed is more important than the precision. Then the question is, can I speed up Eigenvalues[] by ...
5
votes
1answer
397 views

How to speed up calculations with large number of replacement rules?

In my program I have an expression which looks like: ...