  The applications of the recent results obtained in the theory of generalized
Lambert functions, to the mean field theory of ferromagnetism are presented. As
a consequence, all the predictions of the Weiss theory of ferromagnetism can be
explicitly and exactly formulated. In several quantum mechanical problems
involving delta function potentials, the solutions of the transcendental
eigenvalue equations are expressed in terms of two parameters generalized
Lambert functions. Some others, till unnoticed examples of eigenvalue equations
whose solutions can be written using the Lambert W function, are also
presented.
