A = Z1*Z2 t0 = A^2 B = d*t0 D = Y1*Y2 E = X1*D F = E-B G = E+B H = X1-D t1 = X1*Y2 I = t1+Y1 t2 = G*H X3 = c*t2 t3 = F*I Y3 = c*t3 t4 = H*I Z3 = A*t4