def xy_to_upvp(xy):
    """Convert xy to u'v'

    Args:
        xy ([float, float]): x, y input values

    Returns:
        .[float, float]

    """
    x, y = xy
    up = 4 * x / (-2 * x + 12 * y + 3)
    vp = 9 * y / (-2 * x + 12 * y + 3)
    return [up, vp]