In reply to Mon, Apr 14, 2008 at 8:25 AM, Viktor Nagy <viktor.nagy at gmail.com> You write: > M(K) := P.L^(K-1).invert(P)$ I think you want L^^(K-1), the matrix power, not L^(K-1), the element-wise power. By the way, you can also write invert(x) as x^^-1, though there are some subtle differences. -s