diff --git a/README b/README index 27681f78..4ddf1c74 100644 --- a/README +++ b/README @@ -1,23 +1,56 @@ -This directory contains the MLD2P4 set of preconditioners, version 2.1 + + MLD2P4 version 2.1 +MultiLevel Domain Decomposition Parallel Preconditioners Package + based on PSBLAS (Parallel Sparse BLAS version 3.5) + +Salvatore Filippone Cranfield University, UK +Pasqua D'Ambra IAC-CNR, Naples, IT +Daniela di Serafino Univ. of Campania "L. Vanvitelli", Caserta, IT + +--------------------------------------------------------------------- + +MLD2P4 (Multi-Level Domain Decomposition Parallel Preconditioners +Package based on PSBLAS (MLD2P4) provides parallel Algebraic MultiGrid +(AMG) and Domain Decomposition preconditioners, to be used in the +iterative solution of linear systems. + +The name of the package comes from its original implementation, +containing multi-level additive and hybrid Schwarz preconditioners, +as well as one-level additive Schwarz preconditioners. The current +version extends the original plan by including multi-level cycles +and smoothers widely used in multigrid methods. A purely algebraic +approach is applied to generate coarse-level corrections, so that +no geometric background is needed concerning the matrix to be +preconditioned. The matrix is assumed to be square, real or complex. + +MLD2P4 has been designed to provide scalable and easy-to-use +preconditioners in the context of the PSBLAS (Parallel Sparse Basic +Linear Algebra Subprograms) computational framework and is used +in conjuction with the Krylov solvers available from PSBLAS. The +package employs object-oriented design techniques in Fortran 2003, +with interfaces to additional third party libraries such as MUMPS, +UMFPACK, SuperLU, and SuperLU_Dist, which can be exploited in building +multilevel preconditioners. The parallel implementation is based on +a Single Program Multiple Data (SPMD) paradigm; the inter-process +communication is based on MPI and is managed mainly through PSBLAS. + WHAT'S NEW Version 2.1 - 1. The multigrid preconditioner now include fully general V- and W- - cycles. We also support K-cycles, both for symmetric and + 1. The multigrid preconditioner now include fully general V- and + W-cycles. We also support K-cycles, both for symmetric and nonsymmetric matrices, intended to be used in conjunction with Flexible CG or GCR available in PSBLAS 3.5. - 2. The smoothers now include popular - variants such as Jacobi, forward and backward hybrid - Gauss-Seidel (intra-process Gauss-Seidel, inter-process - block-Jacobi). - 3. The PRE and POST specification for smoothers can now be + 2. The smoothers now include popular variants such as Jacobi, + forward and backward hybrid Gauss-Seidel (intra-process + Gauss-Seidel, inter-process block-Jacobi). + 3. The PRE and POST specification for smoothers can now be specified independently of each other: you can even specify different smoothers for PRE and POST (e.g. forward Gauss-Seidel PRE with backward Gauss-Seidel POST). The default is to have the specs apply to both PRE and POST. - Version 2.0. Finally moved to F2003, with the support of PSBLAS3.