! ! ! MLD2P4 version 2.1 ! MultiLevel Domain Decomposition Parallel Preconditioners Package ! based on PSBLAS (Parallel Sparse BLAS version 3.5) ! ! (C) Copyright 2008, 2010, 2012, 2015, 2017 , 2017 ! ! Salvatore Filippone Cranfield University ! Ambra Abdullahi Hassan University of Rome Tor Vergata ! Pasqua D'Ambra IAC-CNR, Naples, IT ! Daniela di Serafino University of Campania "L. Vanvitelli", Caserta, IT ! ! 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 MLD2P4 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 MLD2P4 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: mld_d_dec_map__bld.f90 ! ! Subroutine: mld_d_dec_map_bld ! Version: real ! ! This routine builds the tentative prolongator based on the ! decoupled aggregation algorithm presented in ! ! 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. ! ! Note: upon exit ! ! Arguments: ! a - type(psb_dspmat_type). ! The sparse matrix structure containing the local part of the ! matrix to be preconditioned. ! desc_a - type(psb_desc_type), input. ! The communication descriptor of a. ! p - type(mld_dprec_type), input/output. ! The preconditioner data structure; upon exit it contains ! the multilevel hierarchy of prolongators, restrictors ! and coarse matrices. ! info - integer, output. ! Error code. ! ! ! subroutine mld_d_dec_map_bld(iorder,theta,a,desc_a,nlaggr,ilaggr,info) use psb_base_mod use mld_d_inner_mod, mld_protect_name => mld_d_dec_map_bld implicit none ! Arguments integer(psb_ipk_), intent(in) :: iorder type(psb_dspmat_type), intent(in) :: a type(psb_desc_type), intent(in) :: desc_a real(psb_dpk_), intent(in) :: theta integer(psb_ipk_), allocatable, intent(out) :: ilaggr(:),nlaggr(:) integer(psb_ipk_), intent(out) :: info ! Local variables integer(psb_ipk_), allocatable :: ils(:), neigh(:), irow(:), icol(:),& & ideg(:), idxs(:), tmpaggr(:) real(psb_dpk_), allocatable :: val(:), diag(:) integer(psb_ipk_) :: icnt,nlp,k,n,ia,isz,nr, naggr,i,j,m, nz, ilg, ii, ip type(psb_d_csr_sparse_mat) :: acsr real(psb_dpk_) :: cpling, tcl logical :: disjoint integer(psb_ipk_) :: debug_level, debug_unit,err_act integer(psb_ipk_) :: ictxt,np,me integer(psb_ipk_) :: nrow, ncol, n_ne character(len=20) :: name, ch_err if (psb_get_errstatus() /= 0) return info=psb_success_ name = 'mld_dec_map_bld' 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) nrow = desc_a%get_local_rows() ncol = desc_a%get_local_cols() nr = a%get_nrows() allocate(ilaggr(nr),neigh(nr),ideg(nr),idxs(nr),stat=info) if(info /= psb_success_) then info=psb_err_alloc_request_ call psb_errpush(info,name,i_err=(/2*nr,izero,izero,izero,izero/),& & a_err='integer') goto 9999 end if diag = a%get_diag(info) if(info /= psb_success_) then info=psb_err_from_subroutine_ call psb_errpush(info,name,a_err='psb_sp_getdiag') goto 9999 end if if (iorder == mld_aggr_ord_nat_) then do i=1, nr ilaggr(i) = -(nr+1) idxs(i) = i end do else call a%cp_to(acsr) do i=1, nr ilaggr(i) = -(nr+1) ideg(i) = acsr%irp(i+1) - acsr%irp(i) end do call acsr%free() call psb_msort(ideg,ix=idxs,dir=psb_sort_down_) end if ! ! Phase one: Start with disjoint groups. ! naggr = 0 icnt = 0 step1: do ii=1, nr i = idxs(ii) if (ilaggr(i) == -(nr+1)) then call a%csget(i,i,nz,irow,icol,val,info) if (info /= psb_success_) then info=psb_err_from_subroutine_ call psb_errpush(info,name,a_err='csget') goto 9999 end if ! ! Build the set of all strongly coupled nodes ! ip = 0 do k=1, nz j = icol(k) if ((1<=j).and.(j<=nr)) then if (abs(val(k)) > theta*sqrt(abs(diag(i)*diag(j)))) then ip = ip + 1 icol(ip) = icol(k) end if end if enddo ! ! If the whole strongly coupled neighborhood of I is ! as yet unconnected, turn it into the next aggregate. ! Same if ip==0 (in which case, neighborhood only ! contains I even if it does not look from matrix) ! disjoint = all(ilaggr(icol(1:ip)) == -(nr+1)).or.(ip==0) if (disjoint) then icnt = icnt + 1 naggr = naggr + 1 do k=1, ip ilaggr(icol(k)) = naggr end do ilaggr(i) = naggr end if endif enddo step1 if (debug_level >= psb_debug_outer_) then write(debug_unit,*) me,' ',trim(name),& & ' Check 1:',count(ilaggr == -(nr+1)) end if ! ! Phase two: join the neighbours ! tmpaggr = ilaggr step2: do ii=1,nr i = idxs(ii) if (ilaggr(i) == -(nr+1)) then call a%csget(i,i,nz,irow,icol,val,info) if (info /= psb_success_) then info=psb_err_from_subroutine_ call psb_errpush(info,name,a_err='psb_sp_getrow') goto 9999 end if ! ! Find the most strongly connected neighbour that is ! already aggregated, if any, and join its aggregate ! cpling = dzero ip = 0 do k=1, nz j = icol(k) if ((1<=j).and.(j<=nr)) then if ((abs(val(k)) > theta*sqrt(abs(diag(i)*diag(j))))& & .and. (tmpaggr(j) > 0).and. (abs(val(k)) > cpling)) then ip = k cpling = abs(val(k)) end if end if enddo if (ip > 0) then ilaggr(i) = ilaggr(icol(ip)) end if end if end do step2 ! ! Phase three: sweep over leftovers, if any ! step3: do ii=1,nr i = idxs(ii) if (ilaggr(i) < 0) then call a%csget(i,i,nz,irow,icol,val,info) if (info /= psb_success_) then info=psb_err_from_subroutine_ call psb_errpush(info,name,a_err='psb_sp_getrow') goto 9999 end if ! ! Find its strongly connected neighbourhood not ! already aggregated, and make it into a new aggregate. ! cpling = dzero ip = 0 do k=1, nz j = icol(k) if ((1<=j).and.(j<=nr)) then if ((abs(val(k)) > theta*sqrt(abs(diag(i)*diag(j))))& & .and. (ilaggr(j) < 0)) then ip = ip + 1 icol(ip) = icol(k) end if end if enddo if (ip > 0) then icnt = icnt + 1 naggr = naggr + 1 ilaggr(i) = naggr do k=1, ip ilaggr(icol(k)) = naggr end do else ! ! This should not happen: we did not even connect with ourselves. ! Create an isolate anyway. ! naggr = naggr + 1 ilaggr(i) = naggr end if end if end do step3 if (count(ilaggr<0) >0) then info=psb_err_internal_error_ call psb_errpush(info,name,a_err='Fatal error: some leftovers') goto 9999 endif if (naggr > ncol) then write(0,*) name,'Error : naggr > ncol',naggr,ncol info=psb_err_internal_error_ call psb_errpush(info,name,a_err='Fatal error: naggr>ncol') goto 9999 end if call psb_realloc(ncol,ilaggr,info) if (info /= psb_success_) then info=psb_err_from_subroutine_ ch_err='psb_realloc' call psb_errpush(info,name,a_err=ch_err) goto 9999 end if allocate(nlaggr(np),stat=info) if (info /= psb_success_) then info=psb_err_alloc_request_ call psb_errpush(info,name,i_err=(/np,izero,izero,izero,izero/),& & a_err='integer') goto 9999 end if nlaggr(:) = 0 nlaggr(me+1) = naggr call psb_sum(ictxt,nlaggr(1:np)) call psb_erractionrestore(err_act) return 9999 call psb_error_handler(err_act) return end subroutine mld_d_dec_map_bld