spectralapproximation; since the theory we have developped has received concrete applications for non compact operators only in connection with the Galerkinmethod, we shall now restrict ourself to this case. … The purpose of this part2 of our paper is to give estimâtes of Xby the \iih'$. In fact, we shall adapt to the situation described above Osborn's …
Abstract
One considers an isolated eigenvalue A of finite multiplicity of an operator A which is approximated by a Galerkin method. Using Osborn's technics, one dérives several error estimâtes for X.