Calculates the total number of ways to arrange k items selected from n distinct items, i.e.,
the number of permutations A(n, k) = n! / (n - k)!.
This function is intended for moderate n and k. For very large numbers, consider supporting the 'gmp' package.
Usage
perm(n, k)
Value
Numeric. The permutation count A(n, k) (returns Inf for very large n).
Arguments
n
Integer. Total number of items (non-negative integer).
k
Integer. Number of items selected for permutation (non-negative integer, must be <= n).