A Ruled Surface parameterization
is called noncylindrical if
is nowhere 0. A noncylindrical ruled surface always has a parameterization of the
See also Distribution Parameter, Ruled Surface, Striction Curve
Gray, A. ``Noncylindrical Ruled Surfaces.'' §17.3 in Modern Differential Geometry of Curves and Surfaces.
Boca Raton, FL: CRC Press, pp. 345-349, 1993.