{{alias}}( x, y )
    Returns the positive difference between `x` and `y` if `x > y`; otherwise,
    returns `0`.

    Parameters
    ----------
    x: number
        First number.

    y: number
        Second number.

    Returns
    -------
    out: number
        Positive difference.

    Examples
    --------
    > var v = {{alias}}( 5.9, 3.15 )
    2.75
    > v = {{alias}}( 3.14, 4.2 )
    0.0
    > v = {{alias}}( 3.14, NaN )
    NaN
    > v = {{alias}}( -0.0, +0.0 )
    +0.0

    See Also
    --------