A Ruled Surface is called a generalized cylinder if it can be parameterized by , where is a fixed point. A generalized cylinder is a Regular Surface wherever . The above surface is a generalized cylinder over a Cardioid. A generalized cylinder is a Flat Surface.
See also Cylinder
References
Gray, A. Modern Differential Geometry of Curves and Surfaces. Boca Raton, FL: CRC Press, pp. 341-342, 1993.