Christian Engström
UMIT Research Lab
Department of Mathematics and Mathematical Statistics
Umeå University
Block operator matrices are used to study coupled systems of partial differential equations and problems with a nonlinear dependence of the spectral parameter. In this talk, I focus on Galerkin approximations of rational operator functions and block operator matrices. Simple examples illustrate the principle difficulties and show that a Galerkin approximation can produce results that are completely wrong.