!!$ !!$ !!$ MLD2P4 version 1.1 !!$ MultiLevel Domain Decomposition Parallel Preconditioners Package !!$ based on PSBLAS (Parallel Sparse BLAS version 2.3.1) !!$ !!$ (C) Copyright 2008,2009 !!$ !!$ Salvatore Filippone University of Rome Tor Vergata !!$ Alfredo Buttari CNRS-IRIT, Toulouse !!$ Pasqua D'Ambra ICAR-CNR, Naples !!$ Daniela di Serafino Second University of Naples !!$ !!$ 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_sprecset. ! ! Currently three different prolongators are implemented, corresponding to ! three aggregation algorithms: ! 1. non-smoothed aggregation, ! 2. smoothed aggregation, ! 3. "bizarre" aggregation. ! 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. ! ! 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_sonelev_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. ! ilaggr - integer, dimension(:), allocatable. ! 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. ! nlaggr - integer, dimension(:), allocatable. ! nlaggr(i) contains the aggregates held by process i. ! info - integer, output. ! Error code. ! subroutine mld_saggrmat_asb(a,desc_a,ilaggr,nlaggr,p,info) use psb_sparse_mod use mld_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, intent(inout) :: ilaggr(:), nlaggr(:) type(mld_sonelev_type), intent(inout), target :: p integer, intent(out) :: info ! Local variables integer :: ictxt,np,me, err_act, icomm character(len=20) :: name name='mld_aggrmat_asb' if(psb_get_errstatus().ne.0) return info=psb_success_ call psb_erractionsave(err_act) ictxt = psb_cd_get_context(desc_a) icomm = psb_cd_get_mpic(desc_a) call psb_info(ictxt, me, np) select case (p%iprcparm(mld_aggr_kind_)) case (mld_no_smooth_) call mld_aggrmat_nosmth_asb(a,desc_a,ilaggr,nlaggr,p,info) if(info /= psb_success_) then call psb_errpush(psb_err_from_subroutine_,name,a_err='mld_aggrmat_nosmth_asb') goto 9999 end if case(mld_smooth_prol_,mld_biz_prol_) call mld_aggrmat_smth_asb(a,desc_a,ilaggr,nlaggr,p,info) if(info /= psb_success_) then call psb_errpush(psb_err_from_subroutine_,name,a_err='mld_aggrmat_smth_asb') goto 9999 end if case default call psb_errpush(psb_err_internal_error_,name,a_err='Invalid aggr kind') goto 9999 end select call psb_erractionrestore(err_act) return 9999 continue call psb_erractionrestore(err_act) if (err_act.eq.psb_act_abort_) then call psb_error() return end if return end subroutine mld_saggrmat_asb