The intersection of two NURBS (Non-uniform Rational B-Spline) surfaces has a degree into the hundreds. Those are the surface types used in virtually all CAD mod

The intersection of two NURBS (Non-uniform Rational B-Spline) surfaces has a degree into the hundreds. Those are the surface types used in virtually all CAD modelers. For that reason the intersection is not calculated exactly but approximated to a geometric tolerance. It is harder, mathematically and algorithm-wise to calculate the approximation, but much faster to evaluate afterwards. It's amazing what magic lurks below the surface of even something as simple as "find the intersection of two polynomial functions".