This transformation changes the total angular momentum L and energy E, L → → λ λ L , E → → 1 λ λ 2 E , but preserves their product EL. Therefore, the eccentricity e and the magnitude A are preserved, as may be seen from the equation for A A 2 = m 2 k 2 e 2 = m 2 k 2 + 2 m E L 2 .