# Tagged Questions

Questions about optimizing code for faster results, or how to do faster computations.

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### Duplicate values n-times [on hold]

I already asked how I can take the list {1,2,3} and get {1,1,1,2,2,2,3,3,3} out of it, adding degeneracy to the problem. So far ...
45 views

### More on performance of Sum[]

There is an interesting discussion on performance of Sum[] in this question. I actually wanted to reproduce findings from this answer. So, I entered: ...
46 views

### Speed optimization of Mean calculation in a previous calculated data range

I have following problem: My calculations work quite well with the shown testdata, the only problem is the speed of it. My original dataset is about 64000 datapoints, and it takes several minutes to ...
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### The speed of Sum[] varies strangely

I was curious about the difference in speed between Total and Sum. I found out Total was ...
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### 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. ...
453 views

### Over 30mins to generate the first eigenvector?

Is it normal for Mathematica to take over 30mins to try to compute the first eigenvector of a 100x100 matrix? The matrix is reasonably sparse - about 90% of the cells are 0s and each column sums to ...
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### Improve on timing of NMinimize

I got a little performance problem with the function NMinimize (it takes mathematica approximately 10 minutes to compute the results). Here i s my sample code: ...
129 views

### Neighbourhood - Calculations

SeedRandom[0]; n = 5; (m = N @ RandomInteger[{1, 3}, {n, n}]) // MatrixForm result1 = MeanFilter[m, 1] // MatrixForm ...
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### Speed up numerical optimization (for plotting and solving)?

Briefly speaking, I want to plot a function PIfun[], which its value is based on numerical optimization using NMaximize. It ...
377 views

### Colorize Grayscale Image

I have a grayscale image that contains two objects. The grayscale pixel values can be divided into three intervals where two of them represent objects and the third represents the background. The ...
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### Speeding up the numerical integration of a certain function

I'm using the following function f[t_] := 3/4 t^-3 NIntegrate[(x^4*Csch[x/2]^2), {x, 0, t}, Method -> {Automatic, "SymbolicProcessing" -> 0}]; I ...
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### Timing Differences

In More efficient implementation for comparing coefficient lists in a Do-loop link, george2079 posts in his first answer a piece of code that takes 352 seconds to compute. When I run this same piece ...
I'm wondering how to speed up the following code so it actually computes for $n=2$: ...