How to compute Permutation without repetition?

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.

Answer 1

[Roger Stafford]

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.

[Prasanna Rajbhandari]

Thank you so much. This really helps me. I have 6 sensors and 5 must be chosen with different possible permutations.

[John]

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.

Answer 2

[Syed Faheemuddin]

Check this function which give all the possible permutations without repetition.

[aweller3]

It looks great - I will try it out. Thanks!