See Answers: generating exhaustive permutations for a list of C-Mex files for the memory efficient creation of large permutations/combinations. If your data have integer values, use an integer type to save memory and run-time.
You can create one permutation after the other without repetitions. See. e.g. FEX: nextperm, but as far as I can see, this does not allow repetitions of the elements.
Other useful submission:
You see, searching the FEX is a good idea.
