MLD2P4 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 (MultiLevel Domain Decomposition Parallel Preconditioners Package based on PSBLAS) 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 multilevel additive and hybrid Schwarz preconditioners, as well as one-level additive Schwarz preconditioners. The current version extends the original plan by including multilevel 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. 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. MAIN REFERENCE: P. D'Ambra, D. di Serafino, S. Filippone, MLD2P4: a Package of Parallel Algebraic Multilevel Domain Decomposition Preconditioners in Fortran 95, ACM Transactions on Mathematical Software, 37 (3), 2010, art. 30, doi: 10.1145/1824801.1824808. TO COMPILE 0. Unpack the tar file in a directory of your choice (preferrably outside the main PSBLAS directory). 1. run configure --with-psblas= adding the options for MUMPS, SuperLU, SuperLU_Dist, UMFPACK as desired. See MLD2P4 User's and Reference Guide (Section 3) for details. 2. Tweak Make.inc if you are not satisfied. 3. make; 4. Go into the test subdirectory and build the examples of your choice. NOTES - The single precision version is supported only by MUMPS and SuperLU; thus, even if you specify at configure to use UMFPACK or SuperLU_Dist, the corresponding preconditioner options will be available only from the double precision version. - A program that was using the PSBLAS precoditioners needs no source code changes, but should be recompiled. If the new preconditioner (or preconditioner options, such as ILU(N) factorization) are required, only the type of the preconditioner object and its setup/build/free calls should be updated; the rest of the application continues to make use of the PSBLAS existing interfaces. CREDITS Contributors to version 2: Salvatore Filippone Pasqua D'Ambra Daniela di Serafino Ambra Abdullahi Hassan Contributors to version 1: Salvatore Filippone Pasqua D'Ambra Daniela di Serafino Alfredo Buttari