source 2004 Hankerson--Menezes--Vanstone, page 91
unified
assume Z2=1
compute T1 = Z1^2
compute T2 = T1 Z1
compute T1 = T1 X2
compute T2 = T2 Y2
compute T1 = T1-X1
compute T2 = T2-Y1
compute Z3 = Z1 T1
compute T3 = T1^2
compute T4 = T3 T1
compute T3 = T3 X1
compute T1 = 2 T3
compute X3 = T2^2
compute X3 = X3-T1
compute X3 = X3-T4
compute T3 = T3-X3
compute T3 = T3 T2
compute T4 = T4 Y1
compute Y3 = T3-T4
