/// Sign of Y, magnitude of X (f64)

///

/// Constructs a number with the magnitude (absolute value) of its

/// first argument, `x`, and the sign of its second argument, `y`.

#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]

pub fn copysign(x: f64, y: f64) -> f64 {

    let mut ux = x.to_bits();

    let uy = y.to_bits();

    ux &= (!0) >> 1;

    ux |= uy & (1 << 63);

    f64::from_bits(ux)

}