Steinmetz curve

A Steinmetz curve is the curve of intersection of two right circular cylinders of radii formula_1 and formula_2 whose axes intersect perpendicularly. In case of formula_3 the Steimetz curves are the edges of a Steinmetz solid. If the cylinder axes are the x- and y-axes and formula_4, then the Steinmetz curves are given by the parametric equations:
It is named after mathematician Charles Proteus Steinmetz, along with Steinmetz's equation, Steinmetz solids, and Steinmetz equivalent circuit theory.
In the case when the two cylinders have equal radii the curve degenerates to two intersecting ellipses.