Fitted operator methods for singularly perturbed differential-difference equations via splines

Spline in compression and adaptive spline approaches are used to solve a singularly perturbed differential-difference equation with delay and advanced terms. A fitting factor is used for resolving the boundary layer. Theoretical rate of convergence is calculated and supported by the numerical results for test problems. The layer behavior for various values of the perturbation parameter and the shift parameters is depicted in graphs.