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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2
votes
2answers
61 views

Slow evaluation of Recurrence plot data from NDSolve: Performance Tuning

I am trying to use a recurrence plot to pinpoint the location when a system re-visits a previous point in its phase portrait. The system (a thin liquid film) is governed by a non-linear differential ...
0
votes
0answers
36 views

Data structures in mathematica for choosing permutations

I am trying to classify permutations of n, in this case n=6, elements depending on the cycles that contian the points 1 and 2, since these are considered to be special points. So for example, I will ...
1
vote
1answer
45 views

Control data type (or precison?) to limit memory usage

I couldn't find the answer to my question, so here it is: I have quite a large table, which I generate in Matlab (for some reasons i use both Matlab and Mathematica, I'd like to use only one of them, ...
2
votes
2answers
122 views

Multiple object detection and tracking in images

The code below: reads in a number of png images, where the background is dark and objects of interest (here 3) are bright dots determines in each image the coordinates and other information ...
2
votes
1answer
100 views

Speeding iterative computation

I want to get the following iterative sequence ...
3
votes
1answer
180 views

Alternatives to For/Do Loop to optimize indexing Matrix

I am trying to optimize my code that searches for elements in the rows of matrix that are greater than 0. Then use that position to grab the element from other matrix. I use the do loop to iterate ...
3
votes
1answer
97 views

Efficiently compute this Table of NullSpace

I have two $(2n,2n)$ matrices, $A_1$ and $A_2$, and I would like to compute $$\ker(A_1^p A_2^q -I)$$ for $p,q\leq 2n$. Both matrices are orthogonal and have exactly four non-zeros values on each ...
2
votes
0answers
59 views

How to use Compile? Bivariate Gibbs Sampler

I am trying to use compile to speed up my Gibbs sampler. I know I can use Reap and Sow to speed up tremendously. I have a more complicated Bayesian posterior that I want to speed up with compile so I ...
7
votes
2answers
505 views

How to speed up interpreting numbers from strings?

In processing a large text file I have batches from ReadList of 100,000 Records of the form. ...
0
votes
1answer
43 views

Speeding up WhenEvent + NDSolve (Performance tuning and handling instabilities)

I am solving a non-linear partial differential equation using NDSolve. The equation models a liquid film on an isothermal solid substrate. As a result of various fluid physics mechanisms such as ...
1
vote
1answer
68 views

Keeping determine digits in Append to process

The end of my code is written as below. Ignoring the inefficient role of Append, I want to have very simple set of values as for example: ...
1
vote
2answers
224 views

MatrixPower performs slower than Do loop

I have two almost identical pieces of code: one with MatrixPower responsible for matrix multiplication and another with Do loop. Why the latter performs much faster? It looks counterintuitive... <...
2
votes
1answer
174 views

Compiling in mathematica

I'm trying to compile what I think is a pretty simple function that does matrix multilplications in a loop (see below). But Mathematica issues the message: Could not complete external evaluation ...
1
vote
0answers
72 views

Speed differences between Table, Replace, Array, Map, and AssociationMap

EDIT: Actually, it looks like part of this is bogus—Array doesn't actually work on this input (I'm often a little shaky on what kind of input, exactly, works for ...
11
votes
2answers
264 views

Efficiently generating samples from an urn with maximum per element constraint?

I need to sample from a distribution that is a hybrid of uniform and hypergeometric in the sense that all elements are sampled uniformly until an element reaches some specified maximum observations, ...
1
vote
0answers
70 views

Build basic Adobe Kuler-type construction: improving performance / speed

Adobe Kuler is a useful web tool to create colour palettes, but it is limited to 5 colours. I am trying to make a basic Kuler-type construction, but it is very slow, and crashes on my computer for > ...
5
votes
3answers
185 views

Delete all strings that are prefixes of another string

I have a long list of strings and I'm trying to find a more efficient way of removing those elements that are prefixes of another: ...
16
votes
3answers
525 views

How to speed up estimation of Mean and Gaussian curvatures on triangular meshes?

I am trying to estimate curvatures on a triangulated surface/manifold using the algorithm of : Meyer, M., Desbrun, M., Schröder, P., & Barr, A. H. (2003). Discrete differential-geometry operators ...
2
votes
0answers
43 views

Is there a way to figure out the “upper limit” of my PC's computational ability in Mathematica?

I am doing some simulations with Finite Element Analysis (FEA) and part of it is forming a mesh in 3D and then using NDSolveValue to solve a differential equation on that mesh. For some meshes, my ...
1
vote
1answer
97 views

How to read a part of huge matrix saved in a TXT file as single expression?

I saved a huge matrix of numbers with dimensions {400, 4001, 2} using Put and got a TXT file formatted in the following way: <...
0
votes
1answer
112 views

How to speed up my code for plotting purposes?

Below is my code in order to produce a numerical expression for the final function that needs to be plotted. I have tried to see the output of each successive expression by running the code and ...
2
votes
1answer
52 views

how to use Expand command efficiently

Recently I got in a problem and I will try to explain with a simple example. I have an expression which reads : y = (10 + 2*x )/x; Now I want to substitute 1/x ->...
0
votes
0answers
47 views

How to get ContourPlot3D to run involving elliptic functions?

I need to plot zeroes of a function of three variables that involves elliptic functions. For example, I have ...
15
votes
0answers
160 views

FindMinimum doesn't increase step size when necessary

I've spent much time finding a minimal example demonstrating this problem with FindMinimum. Normally one faces this problem when fitting very large and complicated ...
1
vote
1answer
49 views

Fastest way for data input into StreamPlot function

I'm interested in looking at graphing the phase portraits of 2x2 autonomous ODEs, and I'm using the StreamPlot function. Here is one simple example: ...
3
votes
3answers
105 views

Finding negative sequences in a large list: optimization

I ran across an interesting challenge recently, and I was thinking this community would know how to optimize it. I have several data sets which have (currently) about 50k-100k points. The sets ...
0
votes
0answers
22 views

Text interface + scripts: How to use all available cores

For example, the remote host I'm working on has 12 cores: ...
6
votes
3answers
231 views

How to speed up computation of medoids?

I need to compute medoids (based on SquaredEuclideanDistance for large lists of k-vectors (k = 14). My implementations so far are impractically slow. Here is a ...
1
vote
0answers
35 views

Prevent infinite product from trying to evaluate?

Consider an expression involving several infinite and non-infinite products, like ...
5
votes
0answers
58 views

Inconsistent performance of code

I'm trying to do some optimizations to my code to make it run faster, but it seems that there are inconsistencies in the performance of the code. Namely, the codes have different performance in ...
7
votes
2answers
95 views

TimeSeries interpolation with time gap awareness

Is there an option for ResamplingMethod (or any other practical way) for specifying different behaviours of the interpolation, depending on, for instance, closest dates (on the ...
3
votes
1answer
77 views

Table with programmatically specified number of iterators in Compile

Compare two ways of computing a table of values of a multivariable Gaussian: ...
0
votes
0answers
100 views

Absolute minimum of a function

I would like to ask for some recomendations in order to get a faster result of a function evaluation to get the absolute minimum. In my desperate moments I have written the following code to get the ...
3
votes
0answers
63 views

What's the most efficient way to load a very large dispatch table?

This question is possibly related to this topic, although I think I have something a little more specific in mind. Recently I've been working with dispatch tables for a project, since it seemed like a ...
0
votes
1answer
88 views

Accessing the elements in a table is slower than calculating each time?

This is a follow-up of How to accelerate combinations and sum calculations here? I have tried all tricks but when N reaches 35 the time is still intimidating in a 16-core server, which is far better ...
2
votes
3answers
93 views

Find extremal values while plotting

I have a parametric function {x[t],y[t]}. I then do ...
1
vote
0answers
78 views

Using Map instead of For?

Since i am new to mathematica i tried to do some code with several for-loops. However i saw that mathematica is not efficient with for loops and discovered some functions like map etc. So my question ...
10
votes
2answers
206 views
+150

How to boost the performance of my own BSplineFunction

In my CAGD package, I implemented a CAGDBSplineFunction[] like built-in BSplineFunction[]. ...
17
votes
4answers
353 views

Speedup matrix number multiplication

Consider this simple matrix number multiplication: ...
2
votes
1answer
59 views

How to accelerate combinations and sum calculations here?

I have a 4d matrix H defined as below (embedded with combinations and sums) ...
1
vote
1answer
55 views

Fast Eigensystem calculation

I have a code which finds the eigensystem for a matrix H = H0 + x HInt, where x is a variable which turns on the interaction. H0 is diagonal, and HInt is a sparse matrix (with about 400 states, I hope ...
0
votes
0answers
42 views

Parallelization and efficiency improvement

Hey i am new to mathematica and at the moment i am writing some test code. It works but it is unrefined. I try to make it more efficient by using parallelization or other techniques. I wanted to ask ...
6
votes
2answers
99 views

Speed up AbsoluteTime with string input

I have millions of strings representing dates in the form: "05-Mar-2004 10:15:00". I would like to convert these to absolute times. For example: ...
1
vote
0answers
33 views

Fast Creation of Label Matrix for Use With ComponentMeasurements?

I am taking a lot of measurements from regions of interest in microscopy images and am finding that generating binary masks to use with ComponentMeasurements is rather slow (at least it's slow the way ...
5
votes
0answers
49 views

Is there a way to tell how much time FindRoot is spending calculating Jacobians?

I am solving a large number of trascendental equations by scanning FindRoot over a bunch of seeds and a bunch of different parameter values, and I would like to ...
1
vote
1answer
127 views

Speed Up Sampling of Perimeter of Polygon

I have a polygon whose vertices (points) are defined by some image coordinates that I have manually selected. The polygon is used to create a mask for a region of interest in a microscopy image. ...
0
votes
1answer
78 views

Problems with NMaximize [duplicate]

The Objective function I would like to Maximize takes less than a second to evaluate. There are several packages needed to evaluate it, so I'm not showing it here. ...
6
votes
4answers
218 views

Getting AbsoluteTiming to display in hours, minutes, and seconds

I'm doing some extended length calculations and was wondering how I could get AbsoluteTiming to display in hours, minutes, and seconds. I googled and found nothing, ...
3
votes
3answers
187 views

Replace For with If in Mathematica way

I have this code: ...