Class of wonlinear singnlarly perturbed problems with two layers

Using the matching asymptotic expansion method,a class of third-order nonlinear singularly perturbed varied coefficient boundary value problems with two boundary layers are studied.First,using the direct expansion method,the outer expansion of the solution is obtained,and then introducing the stretched variables,the interior expansions of the solution near the left and right boundary layers are constructed.Finally,according to the matching rules,the asymptotic expansion of the solution is obtained.