This program plots conics (i.e. parabolas, ellipses,
hyperbolas) as well as quadratic curves. The constants that usually
occur in these formula can be changed at will and the curves redrawn.
There are also demonstrations of the definitions of the parabola,
hyperbola and ellipse as the locus of points satisfying certain
conditions as, for example, the ellipse is the locus of points
which sum of distances from these points to the foci is a constant.
(modified from the documentation)