Choose your values for r1, r2 and theta and click the Draw button. Restart to clear the screen. Ellipses will be centred at 0,0 unless you click the mouse somewhere in the stage area (the white area of screen) in which case that will be the centre.
Initially this was to help @hppavilion with angled ellipse http://en.wikipedia.org/wiki/Rotation_matrix is the key.
