I couldn't find a forum section on numerical analysis, so I'm writing this here. I'm on the lookout for simple matrix rotation/multiplication methods that can overcome the precision problems associated with poorly conditioned matrices. In my case I'm trying to simulate the rotational physics of a thin rod, so the inertia tensor I'm using is very poorly conditioned. (In the basic simulator the major spin axis eventually converges on the angular momentum axis, which is at least stable but not ideal.) Or if anyone knows of any fast numerical algorithms designed to integrate rigid body motion, that might be useful as well... thanks!