pub fn frexp(x: f64) -> (f64, i32) {

    let mut y = x.to_bits();

    let ee = ((y >> 52) & 0x7ff) as i32;

    if ee == 0 {

        if x != 0.0 {

            let x1p64 = f64::from_bits(0x43f0000000000000);

            let (x, e) = frexp(x * x1p64);

            return (x, e - 64);

        }

        return (x, 0);

    } else if ee == 0x7ff {

        return (x, 0);

    }

    let e = ee - 0x3fe;

    y &= 0x800fffffffffffff;

    y |= 0x3fe0000000000000;

    return (f64::from_bits(y), e);

}