Asymptotic solution for a critical slab

The problem of a critical slab is solved for both isotropic and anisotropic scattering. The method of strained coordinate, as one of the asymptotic method, is used to render uniformly the perturbation expansion of both the angular flux and the number of secondary neutrons. Numerical calculations show that the oscillation in the value of the number of secondary neutrons obtained by Boffi et al. disappeared. (orig.)