The level set of is the Set of points

and is in the Domain of the function. If , the level set is a plane curve (a level curve). If , the level set is a surface (a level surface).

**References**

Gray, A. ``Level Surfaces in .'' §10.7 in
*Modern Differential Geometry of Curves and Surfaces.*
Boca Raton, FL: CRC Press, pp. 204-207, 1993.

© 1996-9

1999-05-26