
{{alias}}( x, y )
    Returns a double-precision floating-point number with the magnitude of `x`
    and the sign of `x*y`.

    The function only returns `-x` when `y` is a negative number.

    According to the IEEE 754 standard, a `NaN` has a biased exponent equal to
    `2047`, a significand greater than `0`, and a sign bit equal to either `1`
    or `0`. In which case, `NaN` may not correspond to just one but many binary
    representations. Accordingly, care should be taken to ensure that `y` is not
    `NaN`, else behavior may be indeterminate.

    Parameters
    ----------
    x: number
        Number from which to derive a magnitude.

    y: number
        Number from which to derive a sign.

    Returns
    -------
    z: number
        Double-precision floating-point number.

    Examples
    --------
    > var z = {{alias}}( -3.14, 10.0 )
    -3.14
    > z = {{alias}}( -3.14, -1.0 )
    3.14
    > z = {{alias}}( 1.0, -0.0 )
    -1.0
    > z = {{alias}}( -3.14, -0.0 )
    3.14
    > z = {{alias}}( -0.0, 1.0 )
    -0.0
    > z = {{alias}}( 0.0, -1.0 )
    -0.0

    See Also
    --------

