perm: Calculate Number of Permutations A(n, k)

In evanverse: Utility Functions for Data Analysis and Visualization

Calculate Number of Permutations A(n, k)

Description

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)

Arguments

n	Integer. Total number of items (non-negative integer).
k	Integer. Number of items selected for permutation (non-negative integer, must be <= n).

Value

Numeric. The permutation count A(n, k) (returns Inf for very large n).

Examples

perm(8, 4)      # 1680
perm(5, 2)      # 20
perm(10, 0)     # 1
perm(5, 6)      # 0

evanverse documentation built on March 10, 2026, 5:07 p.m.