source 2008 Bernstein--Lange--Rezaeian Farashahi
appliesto wz-1
compute C = W2(Z2+W2)
compute V = C W3(Z3+W3)
compute U = V + d1 (Z2 Z3)^2
compute W4 = C^2
compute Z4 = d1 (Z2^2)^2 + W4
compute W5 = V Z1 + U W1
compute Z5 = U Z1