A numerical study of the plasma presheath has been performed, extending earlier work to include the effects of general source functions, and allowing for collisions in the presheath. Analytic results for a collisionless presheath with particular source functions have been confirmed, and comparisons with a numerical study of a weakly collisional presheath have been made. The extrapolation of these calculations to high collision frequency, where they are compared to a simple analytic model, and the effects of the choice of source functions are presented.