Multigrid conformal mapping via the Szegő kernel.
An algorithm for using the preconditioned conjugate gradient method to solve a coarse level problem is presented.
One method for computing the least eigenvalue of a positive definite matrix of order is described.
In this paper we introduce and analyze some non-overlapping multiplicative Schwarz methods for discontinuous Galerkin (DG) approximations of elliptic problems. The construction of the Schwarz preconditioners is presented in a unified framework for a wide class of DG methods. For symmetric DG approximations we provide optimal convergence bounds for the corresponding error propagation operator, and we show that the resulting methods can be accelerated by using suitable Krylov space solvers. A discussion...