Uniformly convergent schemes for singularly perturbed differential equations based on collocation methods

It is well known that a polynomial-based approximation schemeapplied to a singularly perturbed equation is not uniformlyconvergent over the geometric domain of study. Such scheme resultsin a numerical solution, say σ which suffers from severeinaccuracies particularly in the boundary layer. What we say in thecurrent paper is this: when one uses a grid which is not “toocoarse” the resulted solution, even being nonuniformly convergentmay be used in an iterated scheme to get a “good” approximationsolution that is uniformly convergent over the whole geometricdomain of study.