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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4
votes
2answers
192 views

Animate skips frames and hard to control speed.

I browsed similar questions related to Animate jerkiness like here, but haven't found the right options to control animation rate while also displaying all frames: ...
0
votes
1answer
69 views

Extend a function to all polynomials ( just 2 variables) when one knows its values on monomials

I need your help to make my code faster. I have a formula for computing a value from any monomial $x^i y^j$, say formular1[i_,j_]:=(Gamma[i]/Gamm[j] ). It is just ...
2
votes
1answer
119 views

How to use slots and patterns to reduce repetitive calculation?

This is kind of complicated... How can we make MMa calculate values of a function before doing multiple pattern or slot substitutions? Answers to similar questions didn't cover the case where the ...
0
votes
0answers
47 views

Order of evaluation when using Solve and Minimize

I have to solve numerically an integral, that ends up being more or less as follows: Solve[f[x]==a*Sum[Sin[x-i]*(f[i]-f[i-1]),{i,1,x}],f[x]] (not actual ...
4
votes
1answer
104 views

Most efficient searching algorithm in a table

I am completely new in Mathematica (and in data analysis in general) and I find it really useful, although I still do not use it properly. I have the following question related to data manipulation: ...
3
votes
3answers
129 views

How to pick the maximum of a list? Improving efficiency

I need to find the element of a list, with the highest weight. Example: ...
1
vote
0answers
137 views

Best way to create symmetric matrices with block structure and additional symmetries of the submatrices

Update: you can now skip the "My attempted solution" part and jump to "My first attempt for improvement" in the end of the question. My question is related to Best way to create symmetric matrices . ...
9
votes
1answer
1k views

For loop catastrophe

I know that Mathematica prefers a functional programming way but I still have some problems for the following example. Supposing we generate a Fibonacci sequence of 10^6 elements. NestList or FoldList ...
1
vote
1answer
53 views

Performance of Extract-Transform operations

I'm doing simple data analysis. I load some date-time data from a file, it's a simple list: ...
8
votes
0answers
99 views

How to make Graphics3D with multiple lighting sources being rendered faster

I have a very "precise"(through setting "SpherePoints") Sphere illuminated by hundreds of random color lighting sources. The ...
1
vote
1answer
33 views

Generate Degeneracies in List [duplicate]

I have a list with n entries and I would like to duplicate this list p times. In my case because of the Degeneracy of my Eigenvalues. For example I have {3,2,1} and it is five-fold-degenerate so that ...
5
votes
1answer
247 views

How can I Integrate large trigonometric expressions more efficiently?

I have a requirement to integrate some large symbolic expressions containing products of trigonometric functions. A single integration is averaging 7 minutes, and I have 2628 expressions to integrate, ...
1
vote
1answer
95 views

Apply functions to functions yields slow execution speed

I'm trying to write a function that parametrizes a curve c(t) by its arc length. Technicly I'm finished but if I plot the result for an example curve like ...
15
votes
1answer
319 views

Why does this line increase the consumed memory?

Probably this is a simple question, however I really don't understand this behavior in Mathematica. It particularly leads to a memory leak in a huge program I have to do processing of 3D images. I ...
4
votes
1answer
92 views

Slowdown of Flat attributed function

I was trying to write an associative function f using the attribute Flat. ...
3
votes
1answer
96 views

Mathematica taking too long to calculate recursive function

I have been trying to plot those specific recursively defined functions p1 and q1 in Mathematica: ...
1
vote
1answer
108 views

Use Compile to speed up evaluation

I have read, that using Compile command can speed up evaluations in mathematica. I have a mathematical expression, which I evaluate using following command: ...
2
votes
1answer
68 views

How to handle Indeterminate TimeConstrain

I have to use Timeconstrained[aux] first for avoid some bigs calculation that dont need and it use a lot of time of calculate, so i can't do this. ...
0
votes
0answers
41 views

Faster way to build a specific height in a thickness plane graph? [duplicate]

Test image can be a Plot, ParametricPlot, RegionPlot, ...
14
votes
5answers
2k views

Division by zero is slow

Suppose I have two arrays of data, which I want to divide: ...
6
votes
3answers
195 views

How to get “Signature” of each element of “Permutation” output

I need to sum over all possible permutations, multiplied by the Signature of each permutation of a given list of symbols. But, I don't know how to determine the ...
2
votes
2answers
154 views

Speeding up the generation of all k-edge-coloring of a graph

A $k$-edge-coloring of a graph $G=(V,E)$ is a function from $E$ to $\{1,\ldots,k\}$, so in other words every edge of $G$ receives one of the $k$ colors available. (In particular, note that we are not ...
5
votes
2answers
103 views

How to speed up Min of DateObjects?

I'm in version 10.0.1 using a Dataset to do some plots and things. For one of the plots I need to get the minimum date of a some filtered set of the ...
2
votes
3answers
131 views

Can you compute more terms in this sequence?

I am trying to identify a sequence related to the von Mangoldt function matrix. Since I believe/conjecture that the columns in the matrix have period lengths as in this sequence b: ...
3
votes
1answer
128 views

How to remove recursion, and write it functional and efficient way?

I wish to implement the following recursion efficiently. ...
5
votes
2answers
106 views

Paralleizing the Plot function internally

I have a function of several parameters, funct(a,b,c,d,f,...). Mathematica deals with this function fine but it takes a minute or so to make a data point. I want to plot graphs of funct using code ...
1
vote
1answer
82 views

How to Increase Performance of Manipulate Recalculating List?

I have a list in the form of prices below. ...
17
votes
1answer
654 views

Has this implementation of FDM touched the speed limit of Mathematica?

Still, I'll use the implementation of the 1D FDTD method (you can simply understand it as a kind of explicit finite difference scheme for the Maxwell's equation) as the example. Just for completeness, ...
13
votes
2answers
346 views

Bad performance of LengthWhile?

A friend of mine showed me this example, it's a test comparing LengthWhile to a self-made lengthwhile written in a direct and ...
8
votes
2answers
178 views

Bad performance from SubsetQ?

Can I say this is a bad performance from the new V10 function SubsetQ? Here are some tests comparing it to ...
2
votes
2answers
294 views

Will Parallelize in this programme help it run faster? [closed]

I have a programme, and inside it this line of code. ...
0
votes
1answer
166 views

My Baum-Welch algorithm is very slow. Is it due to Mathematica?

I've also posted this question here, since I'm not sure which community is more adequate for this type of question. I've programmed imperatively the Baum-Welch algorithm for a 2 state hidden Markov ...
5
votes
1answer
234 views

A more perfect Union[]

I was doing a Project Euler problem with my class, and found the following weird fact: Union[] of a list of some 50 million numbers (of which only around 15000 were ...
14
votes
6answers
980 views

Integers which are the sum of both two and three consecutive squares

This is a math problem I came across the other day: $365$ can be written as a sum of two and also three consecutive perfect squares: $365=14^2+13^2=12^2+11^2+10^2$ What is the next ...
5
votes
1answer
85 views

Speedup of KL Divergence by Monte Carlo Simulation

I started with Mathematica about just a week, so I don't know how to take all of this environment. What I want to know is if there is a way to speedup my code to compute the KL-Divergence of Gaussian ...
9
votes
3answers
227 views

Improving selection of elements from large multidimensional array

Frequently in my profession I deal with large arrays of data. Typically these are mixed types including integers, strings, dates, and reals. To recreate a typical data array: ...
0
votes
1answer
128 views

How smart is Solve? Figuring out what tricks I should try

I'm trying to solve a large system (~10000) of linear equations using Solve, but the process keeps failing. As-is, I don't know whether it's failing because it's using too much memory or too much time ...
5
votes
2answers
126 views

Optimizing code containing an infinite sum

I have the following expression. It's based on the negative-log-likelihood of a Poisson-Gaussian noise model, i.e. a convolution of a Poisson & Normal distribution. The value $x_{i}$ is the ...
14
votes
2answers
442 views

Better way to test that a matrix is upper-triangular?

Today, I got to thinking about how to test that a matrix was upper-triangular. So I had a try at it. Algorithm $\quad \quad a_{ij}=0 $ Or $i \leq j$ $\Rightarrow$ $True$ My solution is ...
9
votes
2answers
168 views

Export[] performance

Consider this sequence of commands: ...
3
votes
1answer
98 views

Listable on first level [duplicate]

I have some function which take List as input. f[l_List]:=someActions[l] I need apply this function to a list of lists. Now I ...
7
votes
1answer
157 views

Simpler code evaluating Dickman's function?

I've read here that Mathematica 10 can Obtain symbolic solutions to delay differential equations. Would that help in numericaly evaluating Dickman's function $\rho(u)$ ? It is a delay differential ...
7
votes
3answers
233 views

Issue with very large lists in Mathematica

I have a need to work with very large arrays of data in Mathematica. The length of the list is not known upfront. The typical size is a few hundred thousands elements and could easily go beyond a ...
3
votes
1answer
109 views

How to efficiently select elements from a Hash?

How can I write an efficient version of the following selection statement: Keys[Select[hash, # < constant &]]; // AbsoluteTiming hash can be made from: ...
3
votes
0answers
208 views

Fast principal component analysis

I'd like to speed up a principal value value analysis. The data contains a large set of vectors with a large dimension. Both are in the range of 1000. I want to obtain the loadings matrix for further ...
3
votes
1answer
253 views
2
votes
1answer
72 views

Faster way to extract partial data from AdjacencyMatrix

I am dealing with a lot of Graph objects. One task is to obtain an Id for each of them. So I first used ...
2
votes
0answers
73 views

Mathematica 10 loads too long time [duplicate]

After starting Mathematica 10 it hangs for about a minute before becoming operational. Internet connectivity is disabled. Start screen is disabled. What should I do? P.S. Opening any help page ...
5
votes
1answer
143 views

How to efficiently select element in a list of lists?

How can I write an efficient version of the following statement? Cases[list, {_, feature_} /; feature < constant]; // AbsoluteTiming List is of the form, list ...
15
votes
2answers
250 views

A bug in Commonest in version 10

Bug introduced in 10.0.0 and fixed in 10.0.2 m_goldberg demonstrated that in Mathematica 10 Commonest does not behave as the documentation indicates that it ...