U1 = X1*Z2 U2 = X2*Z1 S1 = Y1*Z2 S2 = Y2*Z1 ZZ = Z1*Z2 T = U1+U2 TT = T^2 M = S1+S2 t0 = ZZ^2 t1 = a*t0 t2 = U1*U2 t3 = TT-t2 R = t3+t1 F = ZZ*M L = M*F LL = L^2 t4 = T+L t5 = t4^2 t6 = t5-TT G = t6-LL t7 = R^2 t8 = 2*t7 W = t8-G t9 = F*W X3 = 2*t9 t10 = 2*W t11 = G-t10 t12 = 2*LL t13 = R*t11 Y3 = t13-t12 t14 = F^2 t15 = F*t14 Z3 = 4*t15