## Conical Spiral

A surface modeled after the shape of a Seashell. One parameterization (left figure) is given by

 (1) (2) (3)

where , and (Wolfram). Nordstrand gives the parameterization
 (4) (5) (6)

for (right figure with , , , and ).

References

Gray, A. Sea Shells.'' §11.6 in Modern Differential Geometry of Curves and Surfaces. Boca Raton, FL: CRC Press, pp. 223-223, 1993.

Nordstrand, T. Conic Spiral or Seashell.'' http://www.uib.no/people/nfytn/shelltxt.htm.

Wolfram Research Mathematica Version 2.0 Graphics Gallery.'' http://www.mathsource.com/cgi-bin/MathSource/Applications/Graphics/3D/0207-155.