source 2002 Billet--Joye "The Jacobi model of an elliptic curve and side-channel analysis", page 6 compute T1 = X1 compute T2 = Y1 compute T3 = Z1 compute T4 = X2 compute T5 = Y2 compute T6 = Z2 compute T7 = T1 T3 compute T7 = T2+T7 compute T8 = T4 T6 compute T8 = T5+T8 compute T2 = T2 T5 compute T7 = T7 T8 compute T7 = T7-T2 compute T5 = T1 T4 compute T1 = T1+T3 compute T8 = T3 T6 compute T4 = T4+T6 compute T6 = T5 T8 compute T7 = T7-T6 compute T1 = T1 T4 compute T1 = T1-T5 compute T1 = T1-T8 compute T3 = T1^2 compute T6 = 2 T6 compute T3 = T3-T6 compute T3 = T3 T6 compute T4 = a T6 compute T2 = T2+T4 compute T4 = T8^2 compute T8 = T5^2 compute T5 = T4+T8 compute T2 = T2 T5 compute T2 = T2+T3 compute T5 = T4-T8 compute X3 = T7 compute Y3 = T2 compute Z3 = T5