global function permute(integer n, sequence set)
--
-- return the nth permute of the given set.
-- n should be an integer in the range 1 to factorial(length(set))
--
sequence res
integer w
    n -= 1
    res = set
    for i=length(set) to 1 by -1 do
        w = remainder(n,i)+1
        res[i] = set[w]
        set[w] = set[i]
        n = floor(n/i)
    end for
    return res
end function