detecting the location of the boundary layers in singular perturbation problems with general linear non-local boundary ‎conditions‎

Singular perturbation problems have been studied by manymathematicians. since theapproximate solutions of these problems are as the sum of internal solution (boundary layer area) and external ones, the formation or non-formation of boundarylayers should be specified. this paper, investigates thisissue for a singular perturbation problem including a first orderdifferential equation with general non-local boundary condition. it needs to say that it is simple for local boundary conditions and there is nodifficulty. however, the formation of boundary layers for non-local case is not as stright forward as local case. to tackle this problem generalized solution of differential equation and some necessary conditions are ‎used