(9) x + yi = w, p + qi = [~omega], r + si = [sigma],
these three pairs of equations may be replaced by the three equations
(10) A :[~omega]_k - K .[~omega]_ki + 2Ta[~omega]_k
- Ta([sigma]_(k+1) + [sigma]_k) = 0,
(11) M :[~omega]_k - T([sigma]_(k+1) - [sigma]_k) = 0,
(12) w_(k+1) - w_k - a([~omega]_(k+1) +
[~omega]_k - 2l[sigma]_(k+1) = 0.