!!$ !!$ !!$ MLD2P4 version 2.0 !!$ MultiLevel Domain Decomposition Parallel Preconditioners Package !!$ based on PSBLAS (Parallel Sparse BLAS version 3.3) !!$ !!$ (C) Copyright 2008, 2010, 2012, 2015 !!$ !!$ 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_scoarse_bld.f90 ! ! Subroutine: mld_scoarse_bld ! Version: real ! ! This routine builds the matrix associated to the current level of the ! multilevel preconditioner from the matrix associated to the previous level, ! by using a smoothed aggregation technique (therefore, it also builds the ! prolongation and restriction operators mapping the current level to the ! previous one and vice versa). Then the routine builds the base preconditioner ! at the current level. ! The current level is regarded as the coarse one, while the previous as ! the fine one. This is in agreement with the fact that the routine is called, ! by mld_mlprec_bld, only on levels >=2. ! ! ! Arguments: ! a - type(psb_sspmat_type). ! The sparse matrix structure containing the local part of the ! fine-level matrix. ! desc_a - type(psb_desc_type), input. ! The communication descriptor of a. ! p - type(mld_s_onelev_type), input/output. ! The 'one-level' data structure containing the local part ! of the base preconditioner to be built as well as ! information concerning the prolongator and its transpose. ! info - integer, output. ! Error code. ! subroutine mld_scoarse_bld(a,desc_a,p,info) use psb_base_mod use mld_s_inner_mod, mld_protect_name => mld_scoarse_bld implicit none ! Arguments type(psb_sspmat_type), intent(in), target :: a type(psb_desc_type), intent(in), target :: desc_a type(mld_s_onelev_type), intent(inout),target :: p integer(psb_ipk_), intent(out) :: info ! Local variables character(len=20) :: name integer(psb_mpik_) :: ictxt, np, me integer(psb_ipk_) :: err_act integer(psb_ipk_), allocatable :: ilaggr(:), nlaggr(:) name='mld_scoarse_bld' if (psb_get_errstatus().ne.0) return call psb_erractionsave(err_act) info = psb_success_ ictxt = desc_a%get_context() call psb_info(ictxt,me,np) call mld_check_def(p%parms%ml_type,'Multilevel type',& & mld_mult_ml_,is_legal_ml_type) call mld_check_def(p%parms%aggr_alg,'Aggregation',& & mld_dec_aggr_,is_legal_ml_aggr_alg) call mld_check_def(p%parms%aggr_kind,'Smoother',& & mld_smooth_prol_,is_legal_ml_aggr_kind) call mld_check_def(p%parms%coarse_mat,'Coarse matrix',& & mld_distr_mat_,is_legal_ml_coarse_mat) call mld_check_def(p%parms%aggr_filter,'Use filtered matrix',& & mld_no_filter_mat_,is_legal_aggr_filter) call mld_check_def(p%parms%smoother_pos,'smooth_pos',& & mld_pre_smooth_,is_legal_ml_smooth_pos) call mld_check_def(p%parms%aggr_omega_alg,'Omega Alg.',& & mld_eig_est_,is_legal_ml_aggr_omega_alg) call mld_check_def(p%parms%aggr_eig,'Eigenvalue estimate',& & mld_max_norm_,is_legal_ml_aggr_eig) call mld_check_def(p%parms%aggr_omega_val,'Omega',szero,is_legal_s_omega) call mld_check_def(p%parms%aggr_thresh,'Aggr_Thresh',szero,is_legal_s_aggr_thrs) ! ! Build a mapping between the row indices of the fine-level matrix ! and the row indices of the coarse-level matrix, according to a decoupled ! aggregation algorithm. This also defines a tentative prolongator from ! the coarse to the fine level. ! call mld_aggrmap_bld(p%parms%aggr_alg,p%parms%aggr_thresh,& & a,desc_a,ilaggr,nlaggr,info) if (info /= psb_success_) then call psb_errpush(psb_err_from_subroutine_,name,a_err='mld_aggrmap_bld') goto 9999 end if ! ! Build the coarse-level matrix from the fine-level one, starting from ! the mapping defined by mld_aggrmap_bld and applying the aggregation ! algorithm specified by p%iprcparm(mld_aggr_kind_) ! call mld_aggrmat_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_asb') goto 9999 end if ! ! Fix the base_a and base_desc pointers for handling of residuals. ! This is correct because this routine is only called at levels >=2. ! p%base_a => p%ac p%base_desc => p%desc_ac call psb_erractionrestore(err_act) return 9999 call psb_error_handler(err_act) return end subroutine mld_scoarse_bld