{{alias}}( y, x )
    Computes the angle in the plane (in radians) between the positive x-axis and
    the ray from (0,0) to the point (x,y).

    Parameters
    ----------
    y: number
        Coordinate along y-axis.

    x: number
        Coordinate along x-axis.

    Returns
    -------
    out: number
        Angle (in radians).

    Examples
    --------
    > var v = {{alias}}( 2.0, 2.0 )
    ~0.785
    > v = {{alias}}( 6.0, 2.0 )
    ~1.249
    > v = {{alias}}( -1.0, -1.0 )
    ~-2.356
    > v = {{alias}}( 3.0, 0.0 )
    ~1.571
    > v = {{alias}}( -2.0, 0.0 )
    ~-1.571
    > v = {{alias}}( 0.0, 0.0 )
    0.0
    > v = {{alias}}( 3.0, NaN )
    NaN
    > v = {{alias}}( NaN, 2.0 )
    NaN

    See Also
    --------