source 1998 Cohen--Miyaji--Ono "Efficient elliptic curve exponentiation using mixed coordinates", formula (3), plus common-subexpression elimination, plus Z2=1
unified
assume Z2 = 1
compute u = Y2 Z1-Y1
compute uu = u^2
compute v = X2 Z1-X1
compute vv = v^2
compute vvv = v vv
compute R = vv X1
compute A = uu Z1-vvv-2 R
compute X3 = v A
compute Y3 = u(R-A)-vvv Y1
compute Z3 = vvv Z1
