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.

learn more… | top users | synonyms (4)

2
votes
1answer
97 views

Compiling a summation

I have a sum over Legendre polynomials which I'm trying to speed up. I've come across the suggestion of using Compile to speed up code in previous answers around ...
0
votes
0answers
29 views
16
votes
2answers
290 views

How to improve performance of BesselJ to the level of GSL?

Consider the following code: zs = N /@ Range[0, 12, 10^-5]; AbsoluteTiming[bessels = BesselJ[1, #] & /@ zs;] Length@zs I've tried to measure only computation ...
14
votes
0answers
199 views

Why is ListPlot so slow here?

While examining How can I monitor the progress of a Plot? I was surprised to discover that in some cases ListPlot in version 10.0 and 10.1 is orders of magnitude ...
4
votes
0answers
73 views

How to perform Bayesian optimization with Mathematica?

Does Mathematica have any Bayesian optimization methods for learning hyper-parameters? Practical Bayesian Optimization of Machine Learning Algorithms Jasper Snoek, Hugo Larochelle and Ryan P. ...
1
vote
1answer
79 views

Apply NonlinearModelFit to an image

I have several images (in FITS format), which I want to fit with a 2D-Gaussian distribution. The problem is that NonlinearModelFit expects data in the form of a ...
5
votes
1answer
120 views

Reap, Sow with Parallelize: bad performance, why?

I have a question about the performance of Reap and Sow with Parallelize. I am aware of the following questions How to collect result continuously (interruptible calculation) when running parallel ...
6
votes
0answers
103 views

Using a Mathematica index as a DiscreteVariable in NDSolve when solving a coupled set of ordinary differential equations

Context Since the explanation below of the problem to be solved is lengthy, let me preamble this by saying that I have code that works to solve the problem, but I don't know whether (1) it's ...
6
votes
3answers
178 views

Speed up derivative evaluation

I'm trying to calculate the normal vectors and the tangent vectors at the discrete points of a suface. For example: ...
4
votes
2answers
248 views

Why does having many Print statements slow down my code?

I have a code that I need to debug. I have put a Print[] into it that should give about 10^4 prints for table entries. I know that 10^4 is large, and this exposes ...
3
votes
1answer
167 views

How to further accelerate arithmetic with Fermat Pseudoprime and Fibonacci number

I've been working on this all night, and I have made this go pretty fast, compared to my first iteration of the program, but now I'm out of ideas. I'm trying to write a program to test (by good ...
1
vote
1answer
131 views

Making ReplaceAll faster

I have a list of functions ncalc that is calculated by ...
1
vote
0answers
54 views

Fast construction and reshaping of large tensors

I'm trying to construct a large matrix which is derived from some higher rank tensor (the rank of interest to me changes case by case, so it needs to be a general method). Currently, the process of ...
11
votes
3answers
482 views

How to speed up Colorize

I have a list of about 500 images similar to the following: A = Import["http://i.stack.imgur.com/1bV4O.png"] ...
8
votes
1answer
230 views

Why is `Block` significantly faster than `ReplaceAll` for inputting variable values

Given that the documentation for FindMinimum uses ReplaceAll for its various examples of what to do with the found solution to ...
4
votes
1answer
90 views

How to create fast functions based on units?

Using units is a good means for rapidly developing code, since it provides some error control. Hovewer, using Mathamatica functions containing units appears to be copmutationally inefficient. ...
0
votes
0answers
74 views

NIntegrate gives message NIntegrate::vars:

As seen in the code below, I initially constructed a list of functions of two variables ζ and t0. These functions are pure ...
11
votes
6answers
570 views

How to find all the positions of max value of a list efficiently?

For Example, list=RandomInteger[{1,100},2000]. Yes,I know Position[list,Max[list]] can do. But it's based on pattern ...
1
vote
0answers
64 views

Orthogonality relations of Hermite polynomials

The Hermite polynomials are orthogonal. $$ \int_{-\infty}^\infty H_m(x) H_n(x) e^{-x^2}\, \mathrm{d}x = \sqrt{ \pi} 2^n n! \delta_{nm} $$ Does Mathematica not use this relationship? Because running ...
14
votes
3answers
616 views

Why is calling Dot with many arguments so inefficient?

Say I want to multiply a reasonably large list of symbolic matrices. ...
18
votes
0answers
267 views

Performance problems in new Sequence functions

The new-in-10.1 Sequence* family of functions should provide newly optimized methods for handling sequence problems. Happily in some cases they do! For example ...
3
votes
1answer
121 views

Constructing lists in an efficient way

I have a list of functions and I want to separate them into two lists: a list that contains the functions that have at least one zero and a list that contains the functions that do not have ...
4
votes
2answers
48 views

NaNs in tabular data and import performance

I'm working with some data files that are just too large for Import. I tried using ReadList, specifying either ...
0
votes
1answer
54 views

Returning functions that are partly evaluated

I have some performance issues when calling Table[{h, Slow1[h, n]}, {n, nlist}, {h, 0.1, 10, 0.5}]; for a given list ...
12
votes
1answer
266 views

Why does partitioning increase Dot execution speed?

I have noticed that multiplying a list of matrices can be significantly sped up by partitioning the list, calculating the product of the partitions matrices, and then multiplying the results. ...
0
votes
0answers
40 views

What is the right way to remove head of a number? [duplicate]

I often have a number for which I want to remove its head, e.g. {1}. I know of two ways to remove the head: {1}[[1]] # & @@ {1} Neither of these methods seem ...
19
votes
2answers
233 views
1
vote
2answers
120 views

Slow program- Mathematica shuts down

I've been trying to draw dynamic pictures of level sets of certain polynomials. The code right now looks like that : ...
5
votes
2answers
146 views

Combinatorics: Placed errors

Consider a vector of length n where each element can take one of the values U, X, ...
0
votes
0answers
23 views

Timing of an Evaluation is not correctly displayed

From: http://reference.wolfram.com/language/howto/DisplayTheTimingOfAnEvaluationInANotebookWindow.html I ran a process that took about two minutes to finish. But the time recorded is only 0.18 ...
0
votes
0answers
37 views

Speeding up a “filling in” process

I have a sparse EventSeries that looks something like ...
4
votes
1answer
73 views

Speed up the auxiliary function magicSquare when $n$ is doubly-even

Today, I saw a question about magic square. Please see here When $n$ is doubly-even.Namely, Mod[n,4]==0 ...
0
votes
0answers
57 views

Computing the coefficients for Gaussian integral

I wrote a small script to find the Gaussian integral points and weights: ...
0
votes
2answers
88 views

Is it possible to sum the results of a Map - Apply?

I am fairly new to functional programming and would like to replace a For[] loop that sums the results over a Dataset. This may be a bit different since the ...
2
votes
0answers
55 views

How to speed up solution of system of recurrence equations

I was wondering how I can improve the speed on this method for solving a particular system of coupled recurrence equations. The system is $$ \begin{align*} &V(m)=\alpha + \beta V(m+1)+\beta ...
2
votes
0answers
53 views

Optimization of custom probability distibutions?

Consider the two tests: Timing[Do[RandomVariate[NormalDistribution[0.5, 0.3]], {200}]] {0.001188, Null} ...
1
vote
2answers
105 views
0
votes
0answers
34 views

How can I find all stationary points? i.e Something like MinDetect but for saddle points (that applies to data arrays of arbitrary rank)

I would like to find all stationary points of a data set of arbitrary rank. MinDetect and MaxDetect are great for finding minima and maxima but I can't find a good way of finding the saddle points. ...
2
votes
1answer
70 views

Faster variant of Reduce for finding zeros of holomorphic functions in a region

I'm currently using Reduce to find zeros of a function in a region on a complex plane: ...
8
votes
4answers
138 views

ImageApply Performance Difference

How come the timing difference between these calls is so big? (0.2 and 39 seconds on my computer) ImageApply[q3, img] ImageApply[q3[#] &, img] Where ...
1
vote
1answer
99 views

Improving Performance - Finding Polynomial Roots [duplicate]

I'm fairly new to Mathematica. In the past, my usage has mostly been limited to solving the occasional equation, making some plots, and working with small scaled statistics. None of these have been ...
11
votes
2answers
188 views

Faster trimming of leading/trailing zeroes in rectangular array

Given a (large) rectangular array, e.g. (small for example case): ...
8
votes
2answers
144 views

why MeanFilter is nearly 100 times slower than MovingAverage for 1D array?

I used to average over my data with MeanFilter before I learn about MovingAverage and thought that these two functions are similar except that MeanFilter is more powerful for its ability to deal with ...
1
vote
1answer
46 views

Speeding up EPS exporting ?

I'm using Mathematica 10 to render some figures, and I'm noticing some strange behaviour with EPS figures. I'm making figures like the one below in EPS format. And to do so, I use some code like ...
3
votes
1answer
143 views

Efficient way to perform local Otsu thresholding on image

I have images of cell nuclei that have locally varying intensity distributions. Therefore, I need a robust local threshold algorithm. LocalAdaptiveBinarize works ...
11
votes
5answers
415 views

Most efficient way of making pair list from a list

I have a bunch of datasets which looks like: 3 7 1 6 5 8 2 4 1 2 8 1 5 2 5 ... and I need to make a list of pairs such that the first element makes a pair with ...
1
vote
0answers
113 views

How can I speed up this NM optimization? Most delay seems to be due to long analytic expression

I am struggling with computational speed of a NelderMead optimization. Nevertheless my impression is that I lose lots of speed not only due to the NM optimization itself but rather to for instance ...
-1
votes
1answer
77 views

Looping within linear programming

I am trying to do some network programming around optimization. Here is a reduced sample: ...
0
votes
0answers
62 views

Optimising prime number test code

Is it possible to speed-up this code ? Also, It would be great if people could test this algorithm. I only have a Raspberry Pi to test it on, so I can't be certain it's not a strong probable prime ...
0
votes
0answers
71 views

Broad Phase Collision Detection with Mathematica and using CUDA

In this and this post, I asked the question about a fast sweep and prune algorithm implementation for broad phase collision detection. To further speed up things a CUDA implementation would be even ...