source 2002 Billet--Joye "The Jacobi model of an elliptic curve and side-channel analysis", page 6, plus specialization to Z2=1
assume Z2 = 1
compute T1 = X1
compute T2 = Y1
compute T3 = Z1
compute T4 = X2
compute T5 = Y2
compute T7 = T1 T3
compute T7 = T2+T7
compute T8 = T4
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
compute T4 = T4+1
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