[shasta]

Two optimizations you can apply:

1. Given how your big integer code is probably implemented, you probably want to distribute the divisions by 2 into the intermediate calculations, rather just shifting by n at the very end.

2. Consider that (a, -b)(c, -d) = (ac + bd, -(bc + ad)). That means that the powers of (1,1) and (1,-1) are always related by negating the second component. Thus you only need to actually compute the power of (1,1) and double it.

[Xk]

Yeah, there are a whole lot of things I could do, but I just wanted a really quick program to see what the relative speeds were. And I have to say I was impressed.