Distributed Schur complement techniques for general sparse linear systems

This paper presents a few preconditioning techniques for solving general sparse linear systems on distributed memory environments. These techniques utilize the Schur complement system for deriving the preconditioning matrix in a number of ways. Two of these preconditioners consist of an approximate solution process for the global system, which exploits approximate LU factorizations for diagonal blocks of the Schur complement. Another preconditioner uses a sparse approximate-inverse technique to obtain certain local approximations of the Schur complement. Comparisons are reported for systems of varying difficulty.