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Help turning a permutation function into a script.

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tban
tban on 7 May 2017
Answered: Andrei Bobrov on 7 May 2017
function [M, I] = permn(V, N)
narginchk(2,3);
if fix(N) ~= N || N < 0 || numel(N) ~= 1 ;
error('permn:negativeN','Second argument should be a positive integer');
end
nV = numel(V) ;
if nargin==2, % PERMN(V,N) - return all permutations
if nV==0 || N == 0,
M = zeros(nV,N) ;
I = zeros(nV,N) ;
elseif N == 1,
M = V(:) ;
I = (1:nV).' ;
else
[Y{N:-1:1}] = ndgrid(1:nV) ;
I = reshape(cat(N+1,Y{:}),[],N) ;
M = V(I) ;
end
end
This code takes two inputs and spits out a list of permutations. Example: permn(2:4,3) gives me this output;
2 2 2
2 2 3
2 2 4
2 3 2
2 3 3
2 3 4
2 4 2
2 4 3
2 4 4
3 2 2
3 2 3
3 2 4
3 3 2
3 3 3
3 3 4
3 4 2
3 4 3
3 4 4
4 2 2
4 2 3
4 2 4
4 3 2
4 3 3
4 3 4
4 4 2
4 4 3
4 4 4
I would like to instead feed the V,N into the script as a variable, and store the output in a matrix.
Since narginchk can only be called in a function can i even do this?
Thanks!

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Answers (1)

Andrei Bobrov
Andrei Bobrov on 7 May 2017
M = V(fliplr(fullfact(ones(1,N)*numel(V))))

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