From: Federico Pernici <pernici@io...>  20010818 17:04:36

Arcot Preetham wrote: > > > Without loss of generality, lets assume the simplest ellipse equation. > > x = a * cos(theta), y = b * sin(theta). > > You can find theta by > theta = atan2(y/b, x/a) > > You can therefore calculate theta_P and theta_Q for points P and Q. > Now, theta_t = (1t)*theta_P + t*theta_Q, t = [0,1] Thank you very much!! It works! But now another pb arise.... How to select (always) the clockwise arc from P to Q ? FEd 