A system of curvilinear coordinates variously denoted (ξ, η, ϕ) or (θ, η, ψ). Using the notation of Arfken, the bispherical coordinates are defined by x | = | (a sin ξ cos ϕ)/(cosh η - cos ξ) y | = | (a sin ξ sin ϕ)/(cosh η - cos ξ) z | = | (a sinh η)/(cosh η - cos ξ).

bicyclide coordinates | Laplace's equation--bispherical coordinates | spherical coordinates | toroidal coordinates