arithmetic-harmonic_mean.sf

#!/usr/bin/ruby

# Daniel "Trizen" Șuteu
# Date: 17 March 2018
# https://github.com/trizen

# Arithmetic-harmonic mean (AHM).

# AHM is equivalent with the geometric mean: AHM(a, b) = sqrt(a * b)

func AHM(a, h, p=100) {

    loop {
        var a1 = ((a + h) / 2)
        var h1 = (2 / (1/a + 1/h))

        if (
            (a1.round(-p) == a.round(-p)) &&
            (h1.round(-p) == h.round(-p))
        ) {
            return a
        }

        (a, h) = (a1,  h1)
    }
}

say AHM(1, 2)         #=> sqrt(1 * 2)
say AHM(2, 5)         #=> sqrt(2 * 5)
say AHM(3, 42)        #=> sqrt(3 * 42)