!!$ !!$ !!$ MLD2P4 version 2.1 !!$ MultiLevel Domain Decomposition Parallel Preconditioners Package !!$ based on PSBLAS (Parallel Sparse BLAS version 3.4) !!$ !!$ (C) Copyright 2008, 2010, 2012, 2015, 2017 !!$ !!$ Salvatore Filippone Cranfield University !!$ Ambra Abdullahi Hassan University of Rome Tor Vergata !!$ Alfredo Buttari CNRS-IRIT, Toulouse !!$ Pasqua D'Ambra ICAR-CNR, Naples !!$ Daniela di Serafino University of Campania "L. Vanvitelli", Caserta !!$ !!$ Redistribution and use in source and binary forms, with or without !!$ modification, are permitted provided that the following conditions !!$ are met: !!$ 1. Redistributions of source code must retain the above copyright !!$ notice, this list of conditions and the following disclaimer. !!$ 2. Redistributions in binary form must reproduce the above copyright !!$ notice, this list of conditions, and the following disclaimer in the !!$ documentation and/or other materials provided with the distribution. !!$ 3. 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File: mld_saggrmat_asb.f90 ! ! Subroutine: mld_saggrmat_asb ! Version: real ! ! This routine builds a coarse-level matrix A_C from a fine-level matrix A ! by using the Galerkin approach, i.e. ! ! A_C = P_C^T A P_C, ! ! where P_C is a prolongator from the coarse level to the fine one. ! ! A mapping from the nodes of the adjacency graph of A to the nodes of the ! adjacency graph of A_C has been computed by the mld_aggrmap_bld subroutine. ! The prolongator P_C is built here from this mapping, according to the ! value of p%iprcparm(mld_aggr_kind_), specified by the user through ! mld_sprecinit and mld_zprecset. ! On output from this routine the entries of AC, op_prol, op_restr ! are still in "global numbering" mode; this is fixed in the calling routine ! mld_s_lev_aggrmat_asb. ! ! Currently four different prolongators are implemented, corresponding to ! four aggregation algorithms: ! 1. un-smoothed aggregation, ! 2. smoothed aggregation, ! 3. "bizarre" aggregation. ! 4. minimum energy ! 1. The non-smoothed aggregation uses as prolongator the piecewise constant ! interpolation operator corresponding to the fine-to-coarse level mapping built ! by mld_aggrmap_bld. This is called tentative prolongator. ! 2. The smoothed aggregation uses as prolongator the operator obtained by applying ! a damped Jacobi smoother to the tentative prolongator. ! 3. The "bizarre" aggregation uses a prolongator proposed by the authors of MLD2P4. ! This prolongator still requires a deep analysis and testing and its use is ! not recommended. ! 4. Minimum energy aggregation: ADD REFERENCE. ! ! For more details see ! M. Brezina and P. Vanek, A black-box iterative solver based on a two-level ! Schwarz method, Computing, 63 (1999), 233-263. ! P. D'Ambra, D. di Serafino and S. Filippone, On the development of PSBLAS-based ! parallel two-level Schwarz preconditioners, Appl. Num. Math., 57 (2007), ! 1181-1196. ! ! ! ! Arguments: ! a - type(psb_sspmat_type), input. ! The sparse matrix structure containing the local part of ! the fine-level matrix. ! desc_a - type(psb_desc_type), input. ! The communication descriptor of the fine-level matrix. ! p - type(mld_s_onelev_type), input/output. ! The 'one-level' data structure that will contain the local ! part of the matrix to be built as well as the information ! concerning the prolongator and its transpose. ! parms - type(mld_sml_parms), input ! Parameters controlling the choice of algorithm ! ac - type(psb_sspmat_type), output ! The coarse matrix on output ! ! ilaggr - integer, dimension(:), input ! The mapping between the row indices of the coarse-level ! matrix and the row indices of the fine-level matrix. ! ilaggr(i)=j means that node i in the adjacency graph ! of the fine-level matrix is mapped onto node j in the ! adjacency graph of the coarse-level matrix. Note that the indices ! are assumed to be shifted so as to make sure the ranges on ! the various processes do not overlap. ! nlaggr - integer, dimension(:) input ! nlaggr(i) contains the aggregates held by process i. ! op_prol - type(psb_sspmat_type), input/output ! The tentative prolongator on input, the computed prolongator on output ! ! op_restr - type(psb_sspmat_type), output ! The restrictor operator; normally, it is the transpose of the prolongator. ! ! info - integer, output. ! Error code. ! subroutine mld_saggrmat_asb(a,desc_a,ilaggr,nlaggr,parms,ac,op_prol,op_restr,info) use psb_base_mod use mld_s_inner_mod, mld_protect_name => mld_saggrmat_asb implicit none ! Arguments type(psb_sspmat_type), intent(in) :: a type(psb_desc_type), intent(in) :: desc_a integer(psb_ipk_), intent(inout) :: ilaggr(:), nlaggr(:) type(mld_sml_parms), intent(inout) :: parms type(psb_sspmat_type), intent(inout) :: ac, op_prol,op_restr integer(psb_ipk_), intent(out) :: info ! Local variables type(psb_s_coo_sparse_mat) :: acoo, bcoo type(psb_s_csr_sparse_mat) :: acsr1 integer(psb_ipk_) :: nzl,ntaggr, err_act integer(psb_ipk_) :: debug_level, debug_unit integer(psb_ipk_) :: ictxt,np,me character(len=20) :: name name='mld_aggrmat_asb' if(psb_get_errstatus().ne.0) return info=psb_success_ call psb_erractionsave(err_act) debug_unit = psb_get_debug_unit() debug_level = psb_get_debug_level() ictxt = desc_a%get_context() call psb_info(ictxt, me, np) select case (parms%aggr_kind) case (mld_no_smooth_) call mld_saggrmat_nosmth_asb(a,desc_a,ilaggr,nlaggr,& & parms,ac,op_prol,op_restr,info) case(mld_smooth_prol_) call mld_saggrmat_smth_asb(a,desc_a,ilaggr,nlaggr, & & parms,ac,op_prol,op_restr,info) case(mld_biz_prol_) call mld_saggrmat_biz_asb(a,desc_a,ilaggr,nlaggr, & & parms,ac,op_prol,op_restr,info) case(mld_min_energy_) call mld_saggrmat_minnrg_asb(a,desc_a,ilaggr,nlaggr, & & parms,ac,op_prol,op_restr,info) case default info = psb_err_internal_error_ call psb_errpush(info,name,a_err='Invalid aggr kind') goto 9999 end select if (info /= psb_success_) then call psb_errpush(psb_err_from_subroutine_,name,a_err='Inner aggrmat asb') goto 9999 end if call psb_erractionrestore(err_act) return 9999 call psb_error_handler(err_act) return end subroutine mld_saggrmat_asb