sidef-scripts/Math/is_perfect_power.sf

#!/usr/bin/ruby

# Algorithm for testing if a given number `n` is a perfect
# power (i.e. can be expressed as: n = a^k with k > 1).

# The value of k is returned when n is an exact k-th power, 1 otherwise.

# Algorithm presented in the book:
#
#   Modern Computer Arithmetic
#           - by Richard P. Brent and Paul Zimmermann
#

func is_perfect_power(n) {

    for k in (n.ilog2 `downto` 2) {
        if (n.iroot(k)**k == n) {
            return k
        }
    }

    return 1
}

say is_perfect_power(1234**14)     #=> 14