I completely grasp the method of turning axis-angle notation to quaternion notation. What I DON''T get is what is MEANT by the formula to rotate a vector v by quaternion q. (FROM THE QUATERNION ARTICLE AT WWW.GAMASUTRA.COM v'' = q v q'' What EXACTLY is this formula stating??? If you have the time on your hands and completely understand HOW to implement this formula in C, please drop a little source code that uses this formula to rotate a vector. I REALLY REALLY appreciate your time, thanks.