
June 14, 2007
12:37 p.m.
I want to choose a subset of all possible permutations of a sequence of length N, with each element of the subset unique. This is then going to be scattered across multiple machines using mpi. Since there is a one-to-one mapping between the integers in the range 0 <= x < N! and the possible permutations, one solution would be to choose M < N! integers randomly, check for uniqueness, and then scatter only the integers so that individual nodes can construct the permutations. However the integers need to be of type long, and randint doesn't work for numbers which cannot be converted to int. Any suggestions?