Conditioning of pseudospectral matrices for certain domain decompositions

Abstract

In this paper we examine the conditioning of the matrices resulting from certain conforming pseudospectral approximations. In particular, we consider non-conforming domain decompositions in rectangular domains and the solution of fourth order problems. We investigate the way in which the poor conditioning of these matrices affects the performance, in terms of accuracy, of various direct methods of solution of the resulting systems. We also show how a simple iterative refinement procedure can improve the accuracy of the results obtained with a capacitance technique.