## Bispherical Coordinates

A system of Curvilinear Coordinates defined by

 (1) (2) (3)

The Scale Factors are
 (4) (5) (6)

The Laplacian is

 (7)

In bispherical coordinates, Laplace's Equation is separable, but the Helmholtz Differential Equation is not.

Arfken, G. Bispherical Coordinates (, , ).'' §2.14 in Mathematical Methods for Physicists, 2nd ed. Orlando, FL: Academic Press, pp. 115-117, 1970.