compute XX = X1^2
compute XXX = X1 XX
compute YY = Y1^2
compute YYY = Y1 YY
compute ZZ = Z1^2
compute ZZZ = Z1 ZZ
compute X3 = Y1(ZZZ-XXX)
compute Y3 = X1(YYY-ZZZ)
compute Z3 = Z1(XXX-YYY)