Abstract
The potential of Fokker-Planck equations with a noninvertible diffusion matrix is calculated by systematically employing a polynomial-expansion approach. About Hopf bifurcation and degenerate Hopf bifurcation points the concrete form of the potential is specified. The analysis is extended to general Fokker-Planck equations, which include Fokker-Planck equations with both invertible and noninvertible diffusion matrices.