Variable step/order generalized upwind methods for the numerical solution of second order singular perturbation problems

We propose a simple and quite efficient code to solve singular perturbation problems when the perturbation parameter is very small. The code is based on generalized upwind methods of order ranging from 4 to 10 and uses highly variable stepsize to fit the boundary regions with relatively few points. An extensive numerical test section shows the effectiveness of the proposed technique on linear problems.