Rank: 2780 based on 26 downloads (last 30 days) and 1 file submitted
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Michal

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28 Nov 2008 fpermute Derives a matrix of all possible permutations of natural numbers 1, 2, ... , N for a given N Author: Michal statistics, mathematics 26 1
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3.0 | 1 rating
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11 Dec 2008 fpermute Derives a matrix of all possible permutations of natural numbers 1, 2, ... , N for a given N Author: Michal Davis, Tim

A few suggestions. First and foremost, this code needs commenting. You have to look at the output matrix to figure out what matrix it's computing. This code has no comments at all. That's really the main reason I give it a rating of 3.

The second reason is that it needs to be redesigned. Wouldn't it make more sense to provide a function that returns each of the n! permutations one at a time? The matrix itself is huge. fpermute(10) returns a (10!)-by-10 matrix, about 3.6 million by 10. Surely an application doesn't need all 3.6 million permutations at the same time.

Something like:

k = 1
[p,k] = next_permutation(n,k)

which increments k. k=1 gives the first one (p=1:n), k=2 the next one, etc.

That would be a useful function. This one is limited by memory requirement to small values of n.
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28 Nov 2008 fpermute Derives a matrix of all possible permutations of natural numbers 1, 2, ... , N for a given N Author: Michal statistics, mathematics 26 1
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3.0 | 1 rating
 

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