How to calculate control points for cubic curve, which approximates an elliptic arc?

Almost all vector graphics applications (like Corel) approximate elliptic arcs with several cubic Bezier curves. I need to add similar functionality to my application. So my question is: h开发者_开发百科ow to calculate control points of that Bezier curve?

There are lots of pages explaining how to do this. This paper by Don Lancaster, for example, gives control parameters for divisions of an ellipse into between 2 and 8 cubic splines, with a detailed analysis of the 4-spline case.