A = Z1*Z2 B = A^2 C = X1*X2 D = Y1*Y2 t0 = C*D E = d*t0 F = B-E G = B+E t1 = X1+Y1 t2 = X2+Y2 t3 = t1*t2 t4 = t3-C t5 = t4-D t6 = F*t5 X3 = A*t6 t7 = D-C t8 = G*t7 Y3 = A*t8 t9 = F*G Z3 = c*t9