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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0
votes
1answer
150 views

How to save the results in an identical Excel file (.xls) in each iteration of a Do loop

Assume the following code (Below code is just an example to clearly illustrate my problem): ...
6
votes
0answers
516 views

Performance tuning - Explicitly set Mathematica use Nvidia GPU for rendering

I feel hesitated to ask this question, but I cannot figure out a way to increase the performance. The problem is about running this featured example on a computer with both Intel HD GPU and Nvidia ...
7
votes
1answer
166 views

Garbage collection for memoized functions on subkernels

I have a top-level function which operates on some data: findBestIntegers[data_]:=ParallelMap[optimize,data] which makes parallelized calls to an optimization ...
16
votes
2answers
440 views

Is there a better way to add elements to a Graphics expression repeatedly?

Consider simple example where a set of points is generated and some are displayed. ...
12
votes
3answers
577 views

Riffle and Partition

At some point I noticed that I was using Riffle and Partition together a lot. I would do things like ...
10
votes
1answer
215 views

Is there a PrimeQ whose accuracy guarantee you can adjust?

Say I have a list of a million integers each with a million digits, and I want a crude sieve to see which have a chance at being prime. Mathematica has a PrimeQ function, which appears to be slow ...
0
votes
0answers
146 views

Manipulate for Electric Field

I'm kind of new to Mathematica but I'm getting the hang of it slowly. Anyways, I'm trying to do a project on the electric field of two particles so my professor helped me with this code (sorry in ...
7
votes
1answer
756 views

Efficient JSON parser for Mathematica

Im looking for a efficient way of parsing JSON data in Mathematica. I am having a lot of problems with ImportString because it uses Java, is too slow, and uses too ...
3
votes
1answer
358 views

Surface area of intersecting spheres

Given a sphere of radius 1 centered at the origin and $n$ spheres with radii $r_i$ centered at predefined coordinates, $c_i$, in space, I am after the surface area of the unit sphere that is not ...
0
votes
0answers
116 views

Linear interpolation over 2 variables [duplicate]

I'm tuning a function to data over 4-5 variables using Differential Evolution. The objective function calls frequently interpolation function. I came to a point, where compiling the objective function ...
3
votes
0answers
127 views

What can I do to improve the performance of my calculations?

I'm trying to express a simple probability problem in Mathematica, but am having trouble getting my calculations to execute at a reasonable speed. I have an object whose unknown location is modeled ...
8
votes
1answer
1k views

Bresenham's line algorithm

Bresenham's line algorithm is producing discretized line for given two points for purpose of plotting for example. Like that: I have to stress that I'm interested in positions, not a plot. ...
13
votes
3answers
1k views

What is the most efficient way to map a linked list?

In order to work with lists effectively using common recursive patterns from functional programming, it's often most convenient to worked with the "linked list" representation, that looks like this: <...
1
vote
2answers
529 views

Research positions of lists of varying size

I'm new to the site and I am French, so I ask your indulgence for my future mistakes in English. I would like to optimise the following code : ...
5
votes
4answers
967 views

Distance between two line segments in 3-space

I need to compute the distance between two line segments in a project. After googling, I found this algorithm and used it to implement a Mathematica version: ...
3
votes
0answers
94 views

Why does setting $Assumptions make my Fourier transforms slow?

Consider these Fourier transforms ...
1
vote
1answer
100 views

Efficient calculation of diagonal matrix elements

I have a matrix $V$ of size $M$ in which each row $i$ is a vector $v_i$. Now I have another matrix $H$ and I would like to calculate as efficiently as possible the list of values $v_i^\dagger\cdot H\...
0
votes
0answers
89 views

Optimization of vector manipulation

I'm trying to implement an upwind scheme for solving transport equation (at first, I work with no right hand side and the simpliest case possible - velocity is constant, initial data is smooth, etc). ...
5
votes
0answers
202 views

Challenge: Speeding up MaxDetect for application in 3D blob detection

In image segmentation it is a common problem that objects appear clustered and are therefore undistinguishable from each other when using simple algorithms. Based on this post I obtained efficient ...
5
votes
1answer
201 views

How to speed up this TDSE code?

I'm trying to build a 1D time-dependent Schrodinger equation solver, using the Crank-Nicholson method. And I think the code is kind of working now, but the speed is still slow for me. Here is the ...
2
votes
1answer
154 views

Performance on Binomial Deviate is slow

I hope I won't get spanked for reposting. This is related to a previous question discussed here: Performance on Multinomial Deviate is slow. but this version is simpler because it is a binomial ...
8
votes
1answer
237 views

Speed up MinimalPolynomial

My Mathematica code runs slowly MinimalPolynomial[Sqrt[2] + Sqrt[3]+ Sqrt[5]+ Sqrt[7]+ Sqrt[11]+ Sqrt[13], x] runs slowly, but the Maple version ...
4
votes
0answers
118 views

LibraryLink parallel performance

I'm trying to use a LibraryLink function in parallel. It is an embarrassingly parallel problem, so that no dependency between those parallel tasks. However I can only get the parallel efficiency about ...
7
votes
0answers
134 views

“Off-label use” of Mathematica functions for performance [closed]

Assisting an acquaintance with a simulation where a very large number of binomial probability calculations are required, I pointed them to a slightly obscure function to dramatically speed up their ...
4
votes
2answers
138 views

Values (or positions) of array row elements within a specified number of positions from target value

I have the need to collect values from the rows of rectangular arrays of arbitrary precision integers, given a target element value and allowed "distance" (positions +/- within the row from found ...
4
votes
2answers
318 views

DynamicModule/Dynamic CheckboxBar Slow for Large Lists

I am trying to create a dynamic construct that takes a large list of expressions and allows the user to interactively select any number of entries for further manipulation. This is what I have ...
2
votes
0answers
527 views

Speeding up Nonlinearmodelfit by constraining parameters?

I have a complicated parametric PDE that can be fitted to some data with NonlinearModelFit, but takes several hours to estimate the best values of the four free parameters. Currently, the code ...
11
votes
5answers
2k views

What is the fastest way to extract a substring from a huge string?

I develop an algorithm to find the most common substrings of a given length n up to a certain distance l in front of a pattern p in a huge sequence S. E.g. I want to find the most common hexamers (...
6
votes
3answers
325 views

Enumerate the 1-factors (perfect matchings) of $K_n$

Introduction I would like to enumerate the 1-factors, or (near-)perfect matchings, of the complete graph Kn. The adjacency list representation for Kn is basically { (x, y) | 1 ≤ x < y ≤ n }. For ...
2
votes
2answers
157 views

Counting Events in a moving date range

I want to count the number of times events take place in a date range. The counting is done over a window of e.g. 28 days where the goal is to have between 11 and 13 events in the time window. The ...
1
vote
2answers
84 views

Extract the real components from a very large expression

Suppose I have a very long expression (>500,000 characters) which contains a mixture of real and imaginary terms. e.g ...
1
vote
0answers
233 views

Speeding up inversion of symbolic matrices by invoking caching

Is it possible to reduce the computation time taken to find inverse of symbolic matrices USING CACHING TECHNIQUES accessible (if any)? I am trying to compute inverse of symbolic matrices of size ...
9
votes
5answers
986 views

Fast way of finding position of Interval containing an Integer

I have a large list (about 2.2 million) of pairs of integers. Each pair defines an Interval[{}]. Given some integer x, I need to ...
1
vote
0answers
72 views

Approximate to the speed of Build-In functions

In Mathematica, there is a function PowerMod[a,b,m], which computes a^b mod m. I will concern only this case: ...
1
vote
1answer
141 views

Code Performance Tuning

The following code takes over 4 seconds to run. Any one has suggestions to make the expressions for qf, phi, ...
10
votes
1answer
347 views

Drop selection of columns from a ragged array

I have an application where I need to drop some arbitrary list of columns from a ragged array (where of course the shortest array rows have at least all the specified columns). E.g., given a ragged ...
1
vote
0answers
53 views

Addition of sparse array objects [duplicate]

Bug introduced in 9.0.0 and fixed in 10.0.0 I have been having some trouble with the addition of large (but very sparse) matrices using SparseArray. Here is the simplest example to illustrate the ...
5
votes
2answers
205 views

Improving performance in the generation of random (directed acyclic) graphs

I need to generate large (directed, acyclic, transitive) graphs. My code in Mathematica gets very slow for large numbers of vertices. I've tried a number of approaches and I can't find any significant ...
1
vote
1answer
167 views

Simulation code performance tuning

The following simulation takes over 20 seconds for evaluation. I have difficulty re-coding it with Nest and Map or Compile functions to make it more efficient. Can some one help with this? The ...
10
votes
8answers
427 views

Fast way to get positions of “boxed” array elements?

Given a 2D array (arbitrary numeric / evaluates to numeric elements, simplified for examples, and can be arbitrary dimensions so long as the operation makes sense, I'm working with 2K X 2K in my ...
7
votes
4answers
668 views

Suppress connection to Wolfram|Alpha when making unit conversions

I want to speed up calculations with unit conversions. I suspect primarily that some units evaluate from Wolfram|Alpha. Any way to prevent this automatically, so that Mathematica throws errors/...
24
votes
1answer
733 views

How to work with Experimental`NumericalFunction?

This question is intimately connected with previous one: "How to create internally optimized expression for computing with high WorkingPrecision?" Oleksandr R. correctly states in the comment: A ...
4
votes
3answers
554 views

Why is my solution to PE #5 so slow

I'm new to Mathematica and it was suggested to me to go through the Project Euler problems in order to learn it. However, I can't quite figure out why my solution to #5 is so slow. The problem: ...
1
vote
0answers
141 views

Increase optimization processing speed

As you know, sometimes numerically solving of optimization problems takes several minutes. For this reason 2 question came up to me: 1 - When one is abort the optimization procedure, how it is ...
2
votes
3answers
379 views

Re-arranging / selecting of a data table very slow in For loop [duplicate]

My task is quite simple; I have a table of data like M = {{1,2}, {1,3}, {3,4}, {5,1}, {6,9}, {6,8}, {6,1}}; so the table is sorted with respect to the first ...
5
votes
1answer
118 views

Why does a heavy background slow LocatorPane from updating, even if only the locators are Dynamic?

I'm having some trouble getting a dynamic plot to operate efficiently, and I think I've tracked down at least part of the problem to some pretty weird behaviour on the part of ...
8
votes
5answers
2k views

Something faster than Do loops with AppendTo

I am an "old" programmer used to Fortran and Pascal. I can't get rid of For, Do and While ...
1
vote
1answer
117 views

Speeding up Integrate and the numerical solution

I want to compute the drag of a plate Below is the code I am using to integrate the function ...
0
votes
1answer
128 views

How I can control the speed with which the cone is filled? [closed]

My idea is: By calculating the speed ie VelVol = v2 * t; where v2 is the volume of the second cone (the amount of "water" that is inserted into the cone) You can see that I have 4 slider (The first ...
0
votes
0answers
46 views

Using Table[ ] vs using Do[Append [ ] ] [duplicate]

Is it generally better/faster to use the Table function over using Do[Append []]? For example, I have this piece of code: <...