A quasi-extrapolation procedure for error estimation of numerical methods in Sturm–Liouville eigenproblems

This paper deals with a generalization of a technique already proposed by the authors for obtaining an effective estimation of the spectral accuracy in some regular and non regular Sturm–Liouville problems. The algorithm looks like a classical extrapolation process, but, unlike such a procedure, it does not require further approximations of the eigenvalues with different stepsize: for this reason it benefits from a moderate computational cost. Numerical experiments confirm the effectiveness of the suggested approach.