2.0 - (0.1 * 2.0 / math.sqrt(0.901 + 1e-5)) -
                (0.5 * (0.1 * 2.0 / math.sqrt(0.901 + 1e-5)) +
                 (0.1 * 2.0 / math.sqrt(0.901 * 0.9 + 0.001 + 1e-5)))