A newly developed discrete ordinate method of solution of differential equations is applied to the solution of the Fokker-Plank equation employed in the a nalysis is of optical bistability. The solution is written in terms of the eigenfunctions of the Fokker-PlancK operator and the time evolution of the probability density function is studied. The present analysis includes a study of the convergence of the eigenualues and eigen functions for different choices of the quadrature rule upon which the discrete ordinate method is based.