# How to compute Permutation without repetition?

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Prasanna Rajbhandari on 6 May 2016
Commented: aweller3 on 26 Nov 2021
We are trying to create a permutation with a,b,c,d,e,f. Taking 5 at a time. We want all the possible permutation without repetition.

Roger Stafford on 6 May 2016
Edited: Roger Stafford on 6 May 2016
If a, b, c, etc. are different numbers, do this:
v = [a,b,c,d,e,f];
P = perms(v);
P = P(:,1:5);
The matrix P will now contain all possible permutations of five elements selected out of v. There will be 720 rows and 5 columns.
If you had asked for, say, all permutations of five numbers chosen out of a larger number like ten, I would have had to do more work above.
##### 2 CommentsShowHide 1 older comment
John on 11 Oct 2017
This answer assumes the result depends on order, i.e. 12345 is different from 21345. If the result is independent of order than use nchoosek(1:6, 5) which produces the six unique combinations
1 2 3 4 5
1 2 3 4 6
1 2 3 5 6
1 2 4 5 6
1 3 4 5 6
2 3 4 5 6
I think selecting 5 out of 6 sensors would be order independent, e.g. 12345 and 21345 are the same selection.

Syed Faheemuddin on 23 Nov 2018
Check this function which give all the possible permutations without repetition.
aweller3 on 26 Nov 2021
It looks great - I will try it out. Thanks!