Math any mathematical surface derived from a 3-D quadratic equation. Quadrics, which are categorized into 16 distinct subfamilies, include all conicoids and conoids as special cases. Math special quadric surfaces including general ellipsoids, paraboloids, and hyperboloids, but typically excluding axisymmetric cases. Math axisymmetric quadric surface generated by revolving a conic section about its axis.
Conoids are the axisymmetric equivalent of conicoids.
Math closed conoid, or ellipsoid of revolution. Math sphere stretched in three mutually perpendicular directions and described by a 3-D quadratic equation. Ellipsoids of revolution are called spheroids.