Calculates the number of ordered arrangements of k items from n distinct items.
P(n, k) = n! / (n - k)!
Arguments
- n
Non-negative integer. Total number of items.
- k
Non-negative integer. Number of items to arrange. Must be <= n.
Value
A numeric value. Returns 0 when k > n, 1 when k = 0.
Examples
perm(8, 4) # 1680
#> [1] 1680
perm(5, 2) # 20
#> [1] 20
perm(10, 0) # 1
#> [1] 1
perm(5, 6) # 0
#> [1] 0
