Talk is cheap.

func Power(base float64, exponent int) float64 {
    r, p := 1.0, 0
    if exponent < 0 {
        p = -exponent
    } else {
        p = exponent
    }
    for p != 0 {
        if p & 1 == 1 { r = r*base }
        base = base*base
        p >>= 1
    }
    if exponent > 0 {
        return r
    } else {
        return 1/r
    }
}