On the use of harmonic Ritz pairs in approximating internal eigenpairs

The goal of this paper is to increase our understanding of harmonic Rayleigh-Ritz for real symmetric matrices. We do this by discussing different, though related topics: a priori error analysis, a posteriori error analysis, a comparison with refined Rayleigh-Ritz and the selection of a suitable harmonic Ritz vector. (C) 2002 Elsevier Science Inc. All rights reserved.