A three-dimensional explicit preconditioned solver

A new class of Generalized Approximate Inverse Matrix (GAIM) techniques, based on the concept of LU-sparse factorization procedures, is introduced for computing explicitly generalized approximate inverses of large sparse unsymmetric matrices of regular structure, without inverting the decomposition factors. Explicit preconditioned iterative methods, in conjunction with modified forms of the GAIM techniques, are presented for solving numerically boundary value problems in three dimensions. The numerical implementation of these algorithms is presented and Fortran subroutines are given