Stagnation analysis of DGMRES

摘要

We study problems for which the iterative method DGMRES for solving Drazin inverse solution of singular linear systems of equations which makes no progress in its initial iterations. Particularly, our tool for analysis is nonlinear system of equations, the stagnation system, that characterize this behavior. For problems of dimension two and index one we can solve this system explicitly. We partially extend this result to higher dimensions for a class of eigenvector matrices called extreme. We also study the real matrices.