COMBINATOR -combinations AND permutations

COMBINATOR will return one of 4 different samplings on the set 1:N, taken K at a time. These samplings are given as follows:

PERMUTATIONS WITH REPETITION/REPLACEMENT
COMBINATOR(N,K,'p','r') -- N >= 1, K >= 0

PERMUTATIONS WITHOUT REPETITION/REPLACEMENT
COMBINATOR(N,K,'p') -- N >= 1, N >= K >= 0

COMBINATIONS WITH REPETITION/REPLACEMENT
COMBINATOR(N,K,'c','r') -- N >= 1, K >= 0

COMBINATIONS WITHOUT REPETITION/REPLACEMENT
COMBINATOR(N,K,'c') -- N >= 1, N >= K >= 0

Example:

combinator(4,2,'p','r') % Permutations with repetition
combinator(4,2,'p') % Permutations without repetition
combinator(4,2,'c','r') % Combinations with repetition
combinator(4,2,'c') % Combinations without repetition
ans =
1 1
1 2
1 3
1 4
2 1
2 2
2 3
2 4
3 1
3 2
3 3
3 4
4 1
4 2
4 3
4 4
ans =
1 2
1 3
1 4
2 1
2 3
2 4
3 1
3 2
3 4
4 1
4 2
4 3
ans =
1 1
1 2
1 3
1 4
2 2
2 3
2 4
3 3
3 4
4 4
ans =
1 2
1 3
1 4
2 3
2 4
3 4

The accompanying c++ file can be MEXed to provide the ability to specify N as an int8, int16, or int32. This saves memory and is faster. I have provided a MEX file that was created on Win XP with 2006a that may work. If not, the file will need to be MEXed on your machine.
Please READ the help before using.
I would very much appreciate bug reports sent through email, as well as suggestions for improvement. Thanks.