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amg4psblas/amgprec/impl/aggregator/amg_d_map_to_tprol.f90

155 lines
5.9 KiB
Fortran

!
!
! AMG4PSBLAS version 1.0
! Algebraic Multigrid Package
! based on PSBLAS (Parallel Sparse BLAS version 3.5)
!
! (C) Copyright 2020
!
! Salvatore Filippone
! Pasqua D'Ambra
! Fabio Durastante
!
! 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. The name of the AMG4PSBLAS group or the names of its contributors may
! not be used to endorse or promote products derived from this
! software without specific written permission.
!
! THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
! ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
! TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
! PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AMG4PSBLAS GROUP OR ITS CONTRIBUTORS
! BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
! CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
! SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
! INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
! CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
! ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
! POSSIBILITY OF SUCH DAMAGE.
!
!
! File: amg_d_map_to_tprol.f90
!
! Subroutine: amg_d_map_to_tprol
! Version: real
!
! This routine uses a mapping from the row indices of the fine-level matrix
! to the row indices of the coarse-level matrix to build a tentative
! prolongator, i.e. a piecewise constant operator.
! This is later used to build the final operator; the code has been refactored here
! to be shared among all the methods that provide the tentative prolongator
! through a simple integer mapping.
!
! The aggregation algorithm is a parallel version of that described in
! * M. Brezina and P. Vanek, A black-box iterative solver based on a
! two-level Schwarz method, Computing, 63 (1999), 233-263.
! * P. Vanek, J. Mandel and M. Brezina, Algebraic Multigrid by Smoothed
! Aggregation for Second and Fourth Order Elliptic Problems, Computing, 56
! (1996), 179-196.
! For more details see
! 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:
! desc_a - type(psb_desc_type), input.
! The communication descriptor of the fine-level matrix.
! 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. Note that on exit the indices
! will be shifted so as to make sure the ranges on the various processes do not
! overlap.
! nlaggr - integer, dimension(:), allocatable.
! nlaggr(i) contains the aggregates held by process i.
! op_prol - type(psb_dspmat_type).
! The tentative prolongator, based on ilaggr.
!
! info - integer, output.
! Error code.
!
subroutine amg_d_map_to_tprol(desc_a,ilaggr,nlaggr,op_prol,info)
use psb_base_mod
use amg_d_inner_mod, amg_protect_name => amg_d_map_to_tprol
implicit none
! Arguments
type(psb_desc_type), intent(in) :: desc_a
integer(psb_lpk_), allocatable, intent(inout) :: ilaggr(:),nlaggr(:)
type(psb_ldspmat_type), intent(out) :: op_prol
integer(psb_ipk_), intent(out) :: info
! Local variables
integer(psb_lpk_) :: icnt,nlp,k,n,ia,isz,nr, naggr,i,j,m,naggrm1, naggrp1, ntaggr
type(psb_ld_coo_sparse_mat) :: tmpcoo
integer(psb_ipk_) :: debug_level, debug_unit,err_act
integer(psb_ipk_) :: ictxt,np,me
integer(psb_lpk_) :: nrow, ncol, n_ne
character(len=20) :: name, ch_err
info=psb_success_
name = 'amg_map_to_tprol'
call psb_erractionsave(err_act)
if (psb_errstatus_fatal()) then
info = psb_err_internal_error_; goto 9999
end if
debug_unit = psb_get_debug_unit()
debug_level = psb_get_debug_level()
!
ictxt=desc_a%get_context()
call psb_info(ictxt,me,np)
nrow = desc_a%get_local_rows()
ncol = desc_a%get_local_cols()
naggr = nlaggr(me+1)
ntaggr = sum(nlaggr)
naggrm1 = sum(nlaggr(1:me))
naggrp1 = sum(nlaggr(1:me+1))
ilaggr(1:nrow) = ilaggr(1:nrow) + naggrm1
call psb_halo(ilaggr,desc_a,info)
if (info /= psb_success_) then
call psb_errpush(psb_err_from_subroutine_,name,a_err='psb_halo')
goto 9999
end if
call tmpcoo%allocate(nrow,ntaggr,ncol)
k = 0
do i=1,nrow
!
! Note: at this point, a value ilaggr(i)<=0
! tags a "singleton" row, and it has to be
! left alone.
!
if (ilaggr(i)>0) then
k = k + 1
tmpcoo%val(k) = done
tmpcoo%ia(k) = i
tmpcoo%ja(k) = ilaggr(i)
end if
end do
call tmpcoo%set_nzeros(k)
call tmpcoo%set_dupl(psb_dupl_add_)
call tmpcoo%set_sorted() ! At this point this is in row-major
call op_prol%mv_from(tmpcoo)
call psb_erractionrestore(err_act)
return
9999 call psb_error_handler(err_act)
return
end subroutine amg_d_map_to_tprol