The weak Galerkin (WG) methods have been introduced in [11, 16] for solving the biharmonic equation. The purpose of this paper is to develop an algorithm to implement the WG methods effectively. This can be achieved by eliminating local unknowns to obtain a global system with significant reduction of size. In fact this reduced global system is equivalent to the Schur complements of the WG metho...

It is well-known [D. Carlson, T. Markham, Schur complements of diagonally dominant matrices, Czech. Math. J. 29 (104) (1979) 246–251, [1]] that the Schur complement of a strictly diagonally dominant matrix is strictly diagonally dominant. Also, if a matrix is an H-matrix, then its Schur complement is an H-matrix, too [J. Liu, Y. Huang, Some properties on Schur complements of H-matrices and diag...

Abstract In previous works, it was suggested to use Steklov eigenvalues for Maxwell equations as target signature nondestructive testing, and recognized that this eigenvalue problem cannot be reformulated a standard compact operator. Consequently, modified with the desired properties proposed. We report apart countable set of particular frequencies, spectrum original self-adjoint consists three...

In this paper, a block LU preconditioner for saddle point problems is presented. The main diierence between the approach presented here and that of other studies is that an explicit, accurate approximation of the Schur complement matrix is eeciently computed. This is used to compute a preconditioner to the Schur complement matrix that in turn deenes a preconditioner for a global iteration. The ...

We show that the decreasing dimension method proposed by Wang and Jiang in \Solution of the System of Linear Algebraic Equations by Decreasing Dimension", Appl. Math. Comput, 109 (2000) 51{57, is a type of Schur complement domain decomposition method. The decreasing dimension method is more expensive than the standard Schur complement domain decomposition method for solving any linear systems. ...

We present a fraction-free approach to the computation of matrix Padé systems. The method relies on determining a modified Schur complement for the coefficient matrices of the linear systems of equations that are associated to matrix Padé approximation problems. By using this modified Schur complement for these matrices we are able to obtain a fast hybrid fraction-free algorithm for their compu...

In this paper we introduce and analyze a new Schur complement approximation based on incomplete Gaussian elimination. The approximate Schur complement is used to develop a multigrid method. This multigrid method has an algorithmic structure that is very similar to the algorithmic structure of classical multigrid methods. The resulting method is almost purely algebraic and has interesting robust...

This thesis presents a parallel resolution method for sparse linear systems which combines effectively techniques of direct and iterative solvers using a Schur complement approach. A domain decomposition is built ; the interiors of the subdomains are eliminated by a direct method in order to use an iterative method only on the interface unknowns. The system on the interface (Schur complement) i...

The goal of this paper is the construction of a data-sparse approximation to the Schur complement on the interface corresponding to FEM and BEM approximations of an elliptic equation by domain decomposition. Using the hierarchical (H-matrix) formats we elaborate the approximate Schur complement inverse in an explicit form. The required cost O(NΓ log q NΓ ) is almost linear in NΓ – the number of...

The goal of this paper is the construction of a data-sparse approximation to the Schur complement on the interface corresponding to FEM and BEM approximations of an elliptic equation by domain decomposition. Using the hierarchical (H-matrix) formats we elaborate the approximate Schur complement inverse in an explicit form. The required cost O(NΓ log NΓ) is almost linear in NΓ – the number of de...