!
!
!                             AMG4PSBLAS version 1.0
!    Algebraic Multigrid Package
!               based on PSBLAS (Parallel Sparse BLAS version 3.7)
!
!    (C) Copyright 2021
!
!        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.
!
module amg_d_decmatch_mod

  use iso_c_binding
  use psb_base_cbind_mod

  interface new_Match_If
    function dnew_Match_If(nr, irp, ja, val, diag, w, mate) &
         & bind(c,name="dnew_Match_If") result(res)
      use iso_c_binding
      import :: psb_c_ipk_, psb_c_lpk_, psb_c_mpk_, psb_c_epk_
      implicit none

      integer(psb_c_ipk_) :: res
      integer(psb_c_ipk_), value :: nr
      
      type(c_ptr), value :: irp, ja, mate
      type(c_ptr), value :: val, diag, w 
    end function dnew_Match_If
  end interface new_Match_If

!!$  interface amg_i_aggr_assign
!!$    module procedure amg_i_daggr_assign
!!$  end interface amg_i_aggr_assign
!!$
  interface amg_build_decmatch
    module procedure amg_dbuild_decmatch
  end interface amg_build_decmatch
!!$
!!$  interface amg_build_ahat
!!$    module procedure amg_dbuild_ahat
!!$  end interface amg_build_ahat
!!$
!!$  interface amg_gtranspose
!!$    module procedure amg_dgtranspose
!!$  end interface amg_gtranspose
!!$
!!$  interface amg_htranspose
!!$    module procedure amg_dhtranspose
!!$  end interface amg_htranspose
!!$
!!$  interface amg_PMatchBox
!!$    module procedure amg_dPMatchBox
!!$  end interface amg_PMatchBox

  logical, parameter, private :: print_statistics=.false.
contains

  subroutine amg_ddecmatch_build_prol(w,a,desc_a,ilaggr,nlaggr,prol,info,&
       & symmetrize,reproducible,display_inp, display_out, print_out)
    use psb_base_mod
    use psb_util_mod
    use iso_c_binding
    implicit none
    real(psb_dpk_), allocatable, intent(inout)  :: w(:)
    type(psb_dspmat_type), intent(inout)        :: a
    type(psb_desc_type)                         :: desc_a
    integer(psb_lpk_), allocatable, intent(out) :: ilaggr(:)
    integer(psb_lpk_), allocatable, intent(out) :: nlaggr(:)
    type(psb_ldspmat_type), intent(out)         :: prol
    integer(psb_ipk_), intent(out)              :: info
    logical, optional, intent(in)               :: display_inp, display_out, reproducible
    logical, optional, intent(in)               :: symmetrize, print_out

    !
    !
    type(psb_ctxt_type) :: ictxt
    integer(psb_ipk_) :: iam, np, iown
    integer(psb_ipk_) :: nr, nc, sweep, nzl, ncsave, nct, idx
    integer(psb_lpk_) :: i, k, kg, idxg, ntaggr, naggrm1, naggrp1, &
         & ip, nlpairs, nlsingl, nunmatched, lnr
    real(psb_dpk_)    :: wk, widx, wmax, nrmagg
    real(psb_dpk_), allocatable    :: wtemp(:)
    integer(psb_ipk_), allocatable :: mate(:)
    integer(psb_lpk_), allocatable ::  ilv(:)
    integer(psb_ipk_), save     :: cnt=1
    character(len=256)          :: aname
    type(psb_ld_coo_sparse_mat) :: tmpcoo
    logical  :: display_out_, print_out_, reproducible_
    logical, parameter  :: dump=.false., debug=.false., dump_mate=.false., &
         & debug_ilaggr=.false., debug_sync=.false.
    integer(psb_ipk_), save :: idx_bldmtc=-1, idx_phase1=-1, idx_phase2=-1, idx_phase3=-1
    logical, parameter :: do_timings=.true.

    ictxt = desc_a%get_ctxt()
    call psb_info(ictxt,iam,np)

    if ((do_timings).and.(idx_phase1==-1))       &
         & idx_phase1 = psb_get_timer_idx("MBP_BLDP: phase1       ")
    if ((do_timings).and.(idx_bldmtc==-1))       &
         & idx_bldmtc = psb_get_timer_idx("MBP_BLDP: buil_matching")
    if ((do_timings).and.(idx_phase2==-1))       &
         & idx_phase2 = psb_get_timer_idx("MBP_BLDP: phase2       ")
    if ((do_timings).and.(idx_phase3==-1))       &
         & idx_phase3 = psb_get_timer_idx("MBP_BLDP: phase3       ")

    if (do_timings) call psb_tic(idx_phase1)

    if (present(display_out)) then
      display_out_ = display_out
    else
      display_out_ = .false.
    end if
    if (present(print_out)) then
      print_out_ = print_out
    else
      print_out_ = .false.
    end if
    if (present(reproducible)) then
      reproducible_ = reproducible
    else
      reproducible_ = .false.
    end if

    allocate(nlaggr(0:np-1),stat=info)
    if (info /= 0) then
      return
    end if

    nlaggr = 0
    ilv    = [(i,i=1,desc_a%get_local_cols())]
    call desc_a%l2gip(ilv,info,owned=.false.)

    call psb_geall(ilaggr,desc_a,info)
    ilaggr = -1
    call psb_geasb(ilaggr,desc_a,info)
    nr = a%get_nrows()
    nc = a%get_ncols()
    if (size(w) < nc) then
      call psb_realloc(nc,w,info)
    end if
    call psb_halo(w,desc_a,info)

    if (debug) write(0,*) iam,' buildprol into buildmatching:',&
         & nr, nc
    if (debug_sync) then
      call psb_barrier(ictxt)
      if (iam == 0) write(0,*)' buildprol into buildmatching:',&
           & nr, nc
    end if
    if (do_timings) call psb_toc(idx_phase1)
    if (do_timings) call psb_tic(idx_bldmtc)
    call amg_dbuild_decmatch(w,a,desc_a,mate,info)
    if (do_timings) call psb_toc(idx_bldmtc)
    if (debug) write(0,*) iam,' buildprol from buildmatching:',&
         & info
    if (debug_sync) then
      call psb_barrier(ictxt)
      if (iam == 0) write(0,*)' out from buildmatching:', info
    end if

    if (info == 0) then
      if (do_timings) call psb_tic(idx_phase2)
      if (debug_sync) then
        call psb_barrier(ictxt)
        if (iam == 0) write(0,*)' Into building the tentative prol:'
      end if

      call psb_geall(wtemp,desc_a,info)
      wtemp      = dzero
      call psb_geasb(wtemp,desc_a,info)

      nlaggr(iam) = 0
      nlpairs    = 0
      nlsingl    = 0
      nunmatched = 0
      !
      ! First sweep
      ! On return from build_matching, mate has been converted to local numbering,
      ! so assigning to idx is OK.
      !
      do k=1, nr
        idx = mate(k)
        !
        ! Figure out an allocation of aggregates to processes
        !
        if (idx < 0) then
          !
          !  Unmatched vertex, potential  singleton.
          !
          nunmatched = nunmatched + 1
          if (abs(w(k))<epsilon(nrmagg)) then
            ! Keep it unaggregated
            wtemp(k) = dzero
          else
            ! Create a singleton aggregate
            nlaggr(iam) = nlaggr(iam) + 1
            ilaggr(k)   = nlaggr(iam)
            wtemp(k)    = w(k)/abs(w(k))
            nlsingl     = nlsingl + 1
          end if
!!$          write(0,*) k,mate(k),ilaggr(k),' negative match ',abs(w(k)), epsilon(nrmagg)
        else  if (idx > nc) then
          write(0,*) 'Impossible: mate(k) > nc'
          cycle
        else

          if (ilaggr(k) == -1) then

            wk   = w(k)
            widx = w(idx)
            wmax = max(abs(wk),abs(widx))
            nrmagg = wmax*sqrt((wk/wmax)**2+(widx/wmax)**2)
            if (nrmagg > epsilon(nrmagg)) then
              if (idx <= nr) then
                if (ilaggr(idx) == -1) then
                  ! Now, if both vertices are local, the aggregate is local
                  ! (kinda obvious).
                  nlaggr(iam) = nlaggr(iam) + 1
                  ilaggr(k)   = nlaggr(iam)
                  ilaggr(idx) = nlaggr(iam)
                  wtemp(k)    = w(k)/nrmagg
                  wtemp(idx)  = w(idx)/nrmagg
                end if
                nlpairs = nlpairs+1
!!$              else if (idx <= nc) then
!!$                !
!!$                ! This pair involves a non-local vertex.
!!$                ! Set wtemp, then apply a tie-breaking algorithm
!!$                wtemp(k)    = w(k)/nrmagg
!!$                idxg  = ilv(idx)
!!$                kg    = ilv(k)
!!$                if (reproducible_) then
!!$                  !
!!$                  ! Tie-break by assigning to the lowest-index process
!!$                  ! so that the numbering is the same as with NP=1
!!$                  !
!!$                  if (kg < idxg) then
!!$                    nlaggr(iam) = nlaggr(iam) + 1
!!$                    ilaggr(k)   = nlaggr(iam)
!!$                    nlpairs = nlpairs+1
!!$                  else
!!$                    ilaggr(k) = -2
!!$                  end if
!!$                else
!!$                  ! Use a statistically unbiased tie-breaking rule,
!!$                  ! this will give an even spread.
!!$                  ! Delegate to i_aggr_assign.
!!$                  ! Should be a symmetric function.
!!$                  !
!!$                  call desc_a%indxmap%qry_halo_owner(idx,iown,info)
!!$! !$                  ip    = amg_i_aggr_assign(iam, iown, kg, idxg, wk, widx, nrmagg)
!!$                  if (iam == ip) then
!!$                    nlaggr(iam) = nlaggr(iam) + 1
!!$                    ilaggr(k)   = nlaggr(iam)
!!$                    nlpairs = nlpairs+1
!!$                  else
!!$                    ilaggr(k) = -2
!!$                  end if
!!$                end if
              else
                write(0,*) 'Really?  mate(k) > nr? ',mate(k),nr
              end if
            else
              if (abs(w(k))<epsilon(nrmagg)) then
                ! Keep it unaggregated
                wtemp(k) = dzero
              else
                ! Create a singleton aggregate
                nlaggr(iam) = nlaggr(iam) + 1
                ilaggr(k)   = nlaggr(iam)
                wtemp(k)    = w(k)/abs(w(k))
                nlsingl     = nlsingl + 1
              end if
            end if
          end if
        end if
      end do
      if (do_timings) call psb_toc(idx_phase2)
      if (do_timings) call psb_tic(idx_phase3)

      ! Ok, now compute offsets, gather halo and fix non-local
      ! aggregates  (those where ilaggr == -2)
      call psb_sum(ictxt,nlaggr)
      ntaggr  = sum(nlaggr(0:np-1))
      naggrm1 = sum(nlaggr(0:iam-1))
      naggrp1 = sum(nlaggr(0:iam))
      !
      ! Shift all indices already assigned (i.e. >0)
      !
      do k=1,nr
        if (ilaggr(k) > 0) then
          ilaggr(k) = ilaggr(k) + naggrm1
!!$        else
!!$          write(0,*) 'Leftover ILAGGR',k,ilaggr(k),mate(k),abs(w(k)),epsilon(nrmagg)
        end if
      end do
      call psb_halo(ilaggr,desc_a,info)
      call psb_halo(wtemp,desc_a,info)
      ! Cleanup as yet unmarked entries
      do k=1,nr
        if (ilaggr(k) == -2) then
          idx = mate(k)
          if (idx > nr) then
            i   = ilaggr(idx)
            if (i > 0) then
              ilaggr(k) = i
            else
              write(0,*) 'Error : unresolved (paired) index ',k,idx,i,nr,nc, ilv(k),ilv(idx)
            end if
          else
            write(0,*) 'Error : unresolved (paired) index ',k,idx,i,nr,nc, ilv(k),ilv(idx)
          end if
        end if
        if (ilaggr(k) <0) then
          write(0,*) 'Decmatch: Funny number: ',k,ilv(k),ilaggr(k),wtemp(k)
        end if
      end do
      if (debug_sync) then
        call psb_barrier(ictxt)
        if (iam == 0) write(0,*)' Done building the tentative prol:'
      end if


      if (dump_mate) then
        block
          integer(psb_lpk_), allocatable :: glaggr(:)
          write(aname,'(a,i3.3,a,i3.3,a)') 'mateg-',cnt,'-p',iam,'.mtx'
          open(20,file=aname)
          write(20,'(a,I3,a)') '% sparse vector on process ',iam,' '
          do k=1, nr
            write(20,'(3(I8,1X))') ilv(k),ilv(mate(k))
          end do
          close(20)
          write(aname,'(a,i3.3,a,i3.3,a)') 'nloc-',cnt,'-p',iam,'.mtx'
          open(20,file=aname)
          write(20,'(a,I3,a)') '% sparse vector on process ',iam,' '
          write(20,'(a,I12,a)') 'nlpairs ',nlpairs
          write(20,'(a,I12,a)') 'nlsingl ',nlsingl
          write(20,'(a,I12,a)') 'nlaggr(iam) ',nlaggr(iam)
          close(20)
          write(aname,'(a,i3.3,a,i3.3,a,i3.3,a)') 'ilaggr-',cnt,'-i',iam,'-p',np,'.mtx'
          open(20,file=aname)
          write(20,'(a,I3,a)') '% sparse vector on process ',iam,' '
          do k=1, nr
            write(20,'(3(I8,1X))') ilv(k),ilaggr(k)
          end do
          close(20)

          write(aname,'(a,i3.3,a,i3.3,a)') 'glaggr-',cnt,'-p',np,'.mtx'
          call psb_gather(glaggr,ilaggr,desc_a,info,root=izero)
          if (iam==0) call mm_array_write(glaggr,'Aggregates ',info,filename=aname)

          cnt=cnt+1
        end block
      end if
      block
        integer(psb_lpk_) :: v(3)
        v(1) = nunmatched
        v(2) = nlsingl
        v(3) = nlpairs
        call psb_sum(ictxt,v)
        nunmatched = v(1)
        nlsingl    = v(2)
        nlpairs    = v(3)

      end block
      if (print_statistics) then
        if (iam == 0) then
          write(0,*) 'Matching statistics: Unmatched nodes ',&
               & nunmatched,' Singletons:',nlsingl,' Pairs:',nlpairs
        end if
      end if
      
      if (display_out_) then
        block
          integer(psb_ipk_) :: idx
          !
          !  And finally print out
          !
          do i=0,np-1
            call psb_barrier(ictxt)
            if (iam == i) then
              write(0,*) 'Process ', iam,' hosts aggregates:  (',naggrm1+1,' : ',naggrp1-1,')'
              do k=1, nr
                idx  = mate(k)
                kg    = ilv(k)
                if (idx >0) then
                  idxg  = ilv(idx)
                else
                  idxg = -1
                end if
                if (idx < 0) then
                  write(0,*) kg,': singleton   (',kg,' ( Proc',iam,') ) into aggregate => ', ilaggr(k)
                else if (idx <= nr) then
                  write(0,*) kg,': paired with (',idxg,' ( Proc',iam,') ) into aggregate => ', ilaggr(k)
                else
                  call desc_a%indxmap%qry_halo_owner(idx,iown,info)
                  write(0,*) kg,': paired with (',idxg,' ( Proc',iown,') ) into aggregate => ', ilaggr(k)
                end if
              end do
              flush(0)
            end if
          end do
        end block
      end if

      ! Dirty trick: allocate tmpcoo with local
      ! number of aggregates, then change to ntaggr.
      ! Just to make sure the allocation is not global
      lnr = nr
      call tmpcoo%allocate(lnr,nlaggr(iam),lnr)
      k = 0
      do i=1,nr
        !
        ! Note: at this point, a value ilaggr(i)<=0
        ! tags an unaggregated row, and it has to be
        ! left alone (i.e.: it should stay at fine level only)
        !
        if (ilaggr(i)>0) then
          k = k + 1
          tmpcoo%val(k) = wtemp(i)
          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() ! This is now in row-major

      if (display_out_) then
        call psb_barrier(ictxt)
        flush(0)

        if (iam == 0) write(0,*) 'Prolongator: '
        flush(0)
        do i=0,np-1
          call psb_barrier(ictxt)
          if (iam == i) then
            do k=1, nr
              write(0,*) ilv(tmpcoo%ia(k)),tmpcoo%ja(k), tmpcoo%val(k)
            end do
            flush(0)
          end if
        end do
      end if

      call prol%mv_from(tmpcoo)
      if (do_timings) call psb_toc(idx_phase3)

      if (print_out_) then
        write(aname,'(a,i3.3,a)') 'prol-g-',iam,'.mtx'
        call prol%print(fname=aname,head='Test ',ivr=ilv)
        write(aname,'(a,i3.3,a)') 'prol-',iam,'.mtx'
        call prol%print(fname=aname,head='Test ')
      end if

    else
      write(0,*) iam,' :  error from Matching: ',info
    end if

  end subroutine amg_ddecmatch_build_prol

!!$  function amg_i_daggr_assign(iam, iown, kg, idxg, wk, widx, nrmagg) &
!!$       & result(iproc)
!!$    !
!!$    ! How to break ties? This
!!$    ! must  be a symmetric function, i.e.
!!$    ! the result value iproc MUST be the same upon
!!$    ! swapping simultaneously all  pairs
!!$    ! (iam,iown) (kg,idxg) (wk,widx)
!!$    !
!!$    implicit none
!!$    integer(psb_ipk_)             :: iproc
!!$    integer(psb_ipk_), intent(in) :: iam, iown
!!$    integer(psb_lpk_), intent(in) :: kg, idxg
!!$    real(psb_dpk_), intent(in)    :: wk, widx, nrmagg
!!$    !
!!$    integer(psb_lpk_) :: kg2, idxg2
!!$
!!$    idxg2 = mod(idxg,2)
!!$    kg2   = mod(kg,2)
!!$
!!$    !
!!$    ! In this particular tie-breaking rule we are ignoring WK, WIDX.
!!$    ! This should statistically entail an even spread of aggregates.
!!$    !
!!$    if ((kg2/=0).and.(idxg2/=0)) then
!!$      ! If both  global indices are  odd,
!!$      !    assign to the higher number process
!!$      iproc = max(iam,iown)
!!$
!!$    else if ((kg2==0).and.(idxg2==0)) then
!!$      ! If both global indices are even,
!!$      !    assign to the lower number process;
!!$      iproc = min(iam,iown)
!!$    else
!!$      ! If the global indices  are mixed,
!!$      !    then  assign to the owner of the odd index
!!$      if (kg2 /= 0) then
!!$        iproc = iam
!!$      else
!!$        iproc = iown
!!$      end if
!!$    end if
!!$  end function amg_i_daggr_assign


  subroutine amg_dbuild_decmatch(w,a,desc_a,mate,info)
    use psb_base_mod
    use psb_util_mod
    use iso_c_binding
    implicit none
    real(psb_dpk_), target                      :: w(:)
    type(psb_dspmat_type), intent(inout)        :: a
    type(psb_desc_type)                         :: desc_a
    integer(psb_ipk_), allocatable, intent(out), target :: mate(:)
    integer(psb_ipk_), intent(out)              :: info

    type(psb_d_csr_sparse_mat), target :: tcsr
    real(psb_dpk_), allocatable, target :: diag(:)
    real(psb_dpk_) :: ph0t,ph1t,ph2t
    type(psb_ctxt_type) :: ictxt
    integer(psb_ipk_) :: iam, np
    integer(psb_ipk_)  :: nr, nc, nz, i, nunmatch
    integer(psb_ipk_), save :: cnt=2
    logical, parameter :: debug=.false., dump_ahat=.false., debug_sync=.false.
    logical, parameter :: old_style=.false., sort_minp=.true.
    character(len=40) :: name='build_matching', fname
    integer(psb_ipk_), save :: idx_cmboxp=-1, idx_bldahat=-1, idx_phase2=-1, idx_phase3=-1
    logical, parameter :: do_timings=.true.

    ictxt = desc_a%get_ctxt()
    call psb_info(ictxt,iam,np)

    nr = a%get_nrows()
    call a%cp_to(tcsr)
    call psb_realloc(nr,mate,info)
    diag = a%get_diag(info)
    !
    ! Now call matching!
    !
    if (debug) write(0,*) iam,' buildmatching into PMatchBox:'
    if (do_timings) call psb_tic(idx_cmboxp)
    info = dnew_Match_If(nr,c_loc(tcsr%irp),c_loc(tcsr%ja),&
         & c_loc(tcsr%val),c_loc(diag),c_loc(w),c_loc(mate))
    if (do_timings) call psb_toc(idx_cmboxp)
    if (debug) write(0,*) iam,' buildmatching from PMatchBox:', info
    if (debug_sync) then
      call psb_max(ictxt,info)
      if (iam == 0) write(0,*)' done PMatchBox', info
    end if

    if (do_timings) call psb_tic(idx_phase3)
    nunmatch = count(mate(1:nr)<=0)
        ! call psb_sum(ictxt,nunmatch)
    if (nunmatch /= 0) write(0,*) iam,' Unmatched nodes local imbalance ',nunmatch
 !    if (count(mate(1:nr)<0) /= nunmatch) write(0,*) iam,' Matching results ?',&
 !        & nunmatch, count(mate(1:nr)<0)
    if (debug_sync) then
      call psb_barrier(ictxt)
      if (iam == 0) write(0,*)' done build_matching '
    end if

    if (do_timings) call psb_toc(idx_phase3)
    return

9999 continue
    call psb_error(ictxt)
!!$  contains
!!$    subroutine fix_order(n,ja,val,iret)
!!$      use psb_base_mod
!!$      implicit none
!!$      integer(psb_ipk_), intent(in)    :: n
!!$      integer(psb_lpk_), intent(inout) :: ja(:)
!!$      real(psb_dpk_), intent(inout)    :: val(:)
!!$      integer(psb_ipk_),intent(out)    :: iret
!!$      integer(psb_lpk_), allocatable   :: ix(:)
!!$      real(psb_dpk_), allocatable      :: tmp(:)
!!$
!!$      allocate(ix(n), tmp(n),stat=iret)
!!$      if (iret /= 0) return
!!$      call psb_msort(ja(1:n),ix=ix,dir=psb_sort_up_)
!!$      tmp(1:n) = val(ix(1:n))
!!$      val(1:n) = tmp(1:n)
!!$    end subroutine fix_order

  end subroutine amg_dbuild_decmatch

!!$  subroutine amg_dbuild_ahat(w,a,ahat,desc_a,info,symmetrize)
!!$    use psb_base_mod
!!$    implicit none
!!$    real(psb_dpk_), intent(in)           :: w(:)
!!$    type(psb_dspmat_type), intent(inout) :: a
!!$    type(psb_dspmat_type), intent(out)   :: ahat
!!$    type(psb_desc_type)                   :: desc_a
!!$    integer(psb_ipk_), intent(out)        :: info
!!$    logical, optional                     :: symmetrize
!!$
!!$    type(psb_dspmat_type)      :: atnd
!!$    type(psb_d_coo_sparse_mat) :: tcoo1, tcoo2, tcoo3
!!$    real(psb_dpk_), allocatable :: diag(:)
!!$    integer(psb_lpk_), allocatable :: ilv(:)
!!$    logical, parameter :: debug=.false., dump=.false., dump_ahat=.false., dump_inp=.false.
!!$    logical :: symmetrize_
!!$    real(psb_dpk_)    :: aii, ajj, aij, wii, wjj, tmp1, tmp2, minabs, edgnrm
!!$    integer(psb_ipk_) :: nr, nc, nz, i, nz2, nrg, ii, jj, k, k2, ncols
!!$    integer(psb_lpk_) :: nzglob
!!$    type(psb_ctxt_type) :: ictxt
!!$    integer(psb_ipk_) :: me, np
!!$    character(len=80) :: aname
!!$    real(psb_dpk_), parameter :: eps=epsilon(1.d0)
!!$    integer(psb_ipk_), save   :: idx_glbt=-1, idx_phase1=-1, idx_phase2=-1
!!$    logical, parameter :: do_timings=.true.
!!$    logical, parameter :: debug_symmetry = .false., check_size=.false.
!!$    logical, parameter :: unroll_logtrans=.false.
!!$
!!$    ictxt = desc_a%get_ctxt()
!!$    call psb_info(ictxt,me,np)
!!$    if (present(symmetrize)) then
!!$      symmetrize_ = symmetrize
!!$    else
!!$      symmetrize_ = .false.
!!$    end if
!!$    if ((do_timings).and.(idx_phase1==-1))       &
!!$         & idx_phase1 = psb_get_timer_idx("BLD_AHAT: phase1       ")
!!$    if ((do_timings).and.(idx_glbt==-1))       &
!!$         & idx_glbt = psb_get_timer_idx("BLD_AHAT: glob_transp")
!!$    if ((do_timings).and.(idx_phase2==-1))       &
!!$         & idx_phase2 = psb_get_timer_idx("BLD_AHAT: phase2       ")
!!$    if (do_timings) call psb_tic(idx_phase1)
!!$    if (dump_inp) then
!!$      block
!!$        type(psb_ldspmat_type) :: amglob
!!$        write(aname,'(a,i3.3,a)') 'a-bld-inp-',me,'.mtx'
!!$        call a%print(fname=aname,head='Test ')
!!$        call psb_gather(amglob,a,desc_a,info)
!!$        if (me==psb_root_) then
!!$          write(aname,'(a,i0,a)') 'a-bld-inp-g-',amglob%get_nrows(),'.mtx'
!!$          call amglob%print(fname=aname,head='Test ')
!!$        end if
!!$      end block
!!$    end if
!!$
!!$    !
!!$    !  Extract diagonal of A
!!$    !
!!$    call a%cp_to(tcoo1)
!!$! !$    call a%triu(atnd,info)
!!$! !$    call atnd%mv_to(tcoo1)
!!$    nr = tcoo1%get_nrows()
!!$    nc = tcoo1%get_ncols()
!!$    nz = tcoo1%get_nzeros()
!!$    diag = a%get_diag(info)
!!$    call psb_realloc(nc,diag,info)
!!$    call psb_halo(diag,desc_a,info)
!!$
!!$    ncols = desc_a%get_local_cols()
!!$    call psb_realloc(ncols,ilv,info)
!!$    do i=1, ncols
!!$      ilv(i) = i
!!$    end do
!!$    call desc_a%l2gip(ilv,info,owned=.false.)
!!$    nr = tcoo1%get_nrows()
!!$    nc = tcoo1%get_ncols()
!!$    nz = tcoo1%get_nzeros()
!!$    call tcoo2%allocate(nr,nc,int(1.25*nz))
!!$    k2 = 0
!!$    !
!!$    ! Build the entries of \^A for matching
!!$    !
!!$    minabs = huge(dzero)
!!$    do k = 1, nz
!!$      ii  = tcoo1%ia(k)
!!$      jj  = tcoo1%ja(k)
!!$      !
!!$      ! Run over only the upper triangle, then transpose.
!!$      ! In theory, A was SPD; in practice, since we
!!$      ! are building the hierarchy with Galerkin products P^T A P,
!!$      ! A will be affected by round-off
!!$      !
!!$      if (ilv(ii)<ilv(jj))  then
!!$        aij = tcoo1%val(k)
!!$        aii = diag(ii)
!!$        ajj = diag(jj)
!!$        wii = w(ii)
!!$        wjj = w(jj)
!!$        edgnrm = aii*(wii**2) + ajj*(wjj**2)
!!$        k2 = k2 + 1
!!$        tcoo2%ia(k2) = ii
!!$        tcoo2%ja(k2) = jj
!!$        if (edgnrm > eps) then
!!$          tcoo2%val(k2) = done - (2*done*aij*wii*wjj)/(aii*(wii**2) + ajj*(wjj**2))
!!$        else
!!$          tcoo2%val(k2) = eps
!!$        end if
!!$      end if
!!$      !else
!!$      !  write(0,*) 'build_ahat: index error :',ii,jj,' : boundaries :',nr,nc
!!$      !end if
!!$    end do
!!$    call tcoo2%set_nzeros(k2)
!!$
!!$    if (dump) then
!!$      block
!!$        type(psb_ldspmat_type) :: amglob
!!$        call ahat%cp_from(tcoo2)
!!$        call psb_gather(amglob,ahat,desc_a,info)
!!$        if (me==psb_root_) then
!!$          write(aname,'(a,i0,a)') 'ahat-gu-',desc_a%get_global_rows(),'.mtx'
!!$          call amglob%print(fname=aname,head='Test ')
!!$        end if
!!$        write(aname,'(a,i0,a,i0,a)') 'ahat-gu-',desc_a%get_global_rows(),'-p',me,'.mtx'
!!$        call ahat%print(fname=aname,head='Test ',iv=ilv)
!!$        write(aname,'(a,i0,a,i0,a)') 'ainp-ahat-',desc_a%get_global_rows(),'-p',me,'.mtx'
!!$        call a%print(fname=aname,head='Test ',iv=ilv)
!!$        call psb_gather(amglob,a,desc_a,info)
!!$        if (me==psb_root_) then
!!$          write(aname,'(a,i0,a)') 'ainp-ahat-g-',desc_a%get_global_rows(),'.mtx'
!!$          call amglob%print(fname=aname,head='Test ')
!!$        end if
!!$        write(0,*) 'Done build_ahat'
!!$      end block
!!$    end if
!!$    if (do_timings) call psb_toc(idx_phase1)
!!$    if (do_timings) call psb_tic(idx_glbt)
!!$
!!$    call psb_glob_transpose(tcoo2,desc_a,info,atrans=tcoo1)
!!$    if (do_timings) call psb_toc(idx_glbt)
!!$    if (do_timings) call psb_tic(idx_phase2)
!!$    if (dump) then
!!$      block
!!$        type(psb_ldspmat_type) :: amglob
!!$        call atnd%cp_from(tcoo1)
!!$        call psb_gather(amglob,atnd,desc_a,info)
!!$        if (me==psb_root_) then
!!$          write(aname,'(a,i0,a)') 'ahat-gl-',desc_a%get_global_rows(),'.mtx'
!!$          call amglob%print(fname=aname,head='Test ')
!!$        end if
!!$        write(aname,'(a,i0,a,i0,a)') 'ahat-gl-',desc_a%get_global_rows(),'-p',me,'.mtx'
!!$        call ahat%print(fname=aname,head='Test ',iv=ilv)
!!$        write(0,*) 'Done build_ahat'
!!$      end block
!!$    end if
!!$
!!$    nz  = tcoo1%get_nzeros()
!!$    nz2 = tcoo2%get_nzeros()
!!$    call tcoo2%ensure_size(nz+nz2)
!!$    tcoo2%ia(nz2+1:nz2+nz) = tcoo1%ia(1:nz)
!!$    tcoo2%ja(nz2+1:nz2+nz) = tcoo1%ja(1:nz)
!!$    tcoo2%val(nz2+1:nz2+nz) = tcoo1%val(1:nz)
!!$    call tcoo2%set_nzeros(nz+nz2)
!!$    call tcoo2%fix(info)
!!$    call tcoo1%free()
!!$    nz = tcoo2%get_nzeros()
!!$    if (unroll_logtrans) then
!!$      minabs = huge(dzero)
!!$      do k = 1, nz
!!$        tcoo2%val(k) = abs(tcoo2%val(k))
!!$        minabs = min(minabs,tcoo2%val(k))
!!$      end do
!!$    else
!!$      minabs = minval(abs(tcoo2%val(1:nz)))
!!$    end if
!!$    call psb_min(ictxt,minabs)
!!$    if (minabs <= dzero) then
!!$      if (me == 0) write(0,*) me, 'Min value for log correction is <=zero! '
!!$      minabs = done
!!$    end if
!!$    if (unroll_logtrans) then
!!$      do k = 1, nz
!!$        ! tcoo2%val has already been subject to abs() above.
!!$        tcoo2%val(k) = log(tcoo2%val(k)/(0.999*minabs))
!!$        if (tcoo2%val(k)<0)  write(0,*) me, 'Warning: negative log output!'
!!$      end do
!!$    else
!!$      tcoo2%val(1:nz) = log(abs(tcoo2%val(1:nz))/(0.999*minabs))
!!$      if (any(tcoo2%val(1:nz)<0))  write(0,*) me, 'Warning: negative log output!'
!!$    end if
!!$
!!$    call ahat%mv_from(tcoo2)
!!$
!!$    if (do_timings) call psb_toc(idx_phase2)
!!$
!!$    if (check_size) then
!!$      nzglob = ahat%get_nzeros()
!!$      call psb_sum(ictxt,nzglob)
!!$      if (me==0) write(0,*) 'From build_ahat: global nzeros ',desc_a%get_global_rows(),nzglob
!!$    end if
!!$    if (debug_symmetry) then
!!$      block
!!$        integer(psb_ipk_) :: nz1, nz2
!!$        real(psb_dpk_)    :: mxv
!!$        call ahat%cp_to(tcoo1)
!!$        call psb_glob_transpose(tcoo1,desc_a,info,atrans=tcoo2)
!!$        nz1 = tcoo1%get_nzeros()
!!$        nz2 = tcoo2%get_nzeros()
!!$        call tcoo1%reallocate(nz1+nz2)
!!$        tcoo1%ia(nz1+1:nz1+nz2)  = tcoo2%ia(1:nz2)
!!$        tcoo1%ja(nz1+1:nz1+nz2)  = tcoo2%ja(1:nz2)
!!$        tcoo1%val(nz1+1:nz1+nz2) = -tcoo2%val(1:nz2)
!!$        call tcoo1%set_nzeros(nz1+nz2)
!!$        call tcoo1%set_dupl(psb_dupl_add_)
!!$        call tcoo1%fix(info)
!!$        nz1 = tcoo1%get_nzeros()
!!$        mxv = maxval(abs(tcoo1%val(1:nz1)))
!!$        call psb_max(ictxt,mxv)
!!$        if (me==0) write(0,*) 'Maximum disp from symmetry:',mxv
!!$      end block
!!$    end if
!!$
!!$    if (dump_ahat) then
!!$      block
!!$        type(psb_ldspmat_type) :: amglob
!!$        write(aname,'(a,i3.3,a)') 'ahat-hfa-l-',me,'.mtx'
!!$        call ahat%print(fname=aname,head='Test ')
!!$        call psb_gather(amglob,ahat,desc_a,info)
!!$        if (me==psb_root_) then
!!$          write(aname,'(a,i0,a)') 'ahat-hfa-g-',amglob%get_nrows(),'.mtx'
!!$          call amglob%print(fname=aname,head='Test ')
!!$        end if
!!$        write(0,*) 'Done build_ahat'
!!$      end block
!!$    end if
!!$
!!$  end subroutine amg_dbuild_ahat
!!$
!!$  subroutine amg_dgtranspose(ain,aout,desc_a,info)
!!$    use psb_base_mod
!!$    implicit none
!!$    type(psb_ldspmat_type), intent(in)  :: ain
!!$    type(psb_ldspmat_type), intent(out) :: aout
!!$    type(psb_desc_type)           :: desc_a
!!$    integer(psb_ipk_), intent(out) :: info
!!$
!!$    !
!!$    ! BEWARE: This routine works under the assumption
!!$    ! that the same DESC_A works for both A and A^T, which
!!$    ! essentially means that A has a symmetric pattern.
!!$    !
!!$    type(psb_ldspmat_type) :: atmp, ahalo, aglb
!!$    type(psb_ld_coo_sparse_mat) :: tmpcoo
!!$    type(psb_ld_csr_sparse_mat) :: tmpcsr
!!$    type(psb_ctxt_type) :: ictxt
!!$    integer(psb_ipk_) :: me, np
!!$    integer(psb_lpk_) :: i, j, k, nrow, ncol
!!$    integer(psb_lpk_), allocatable :: ilv(:)
!!$    character(len=80) :: aname
!!$    logical, parameter :: debug=.false., dump=.false., debug_sync=.false.
!!$
!!$    ictxt = desc_a%get_context()
!!$    call psb_info(ictxt,me,np)
!!$
!!$    nrow = desc_a%get_local_rows()
!!$    ncol = desc_a%get_local_cols()
!!$    if (debug_sync) then
!!$      call psb_barrier(ictxt)
!!$      if (me == 0) write(0,*) 'Start gtranspose '
!!$    end if
!!$    call ain%cscnv(tmpcsr,info)
!!$
!!$    if (debug) then
!!$      ilv = [(i,i=1,ncol)]
!!$      call desc_a%l2gip(ilv,info,owned=.false.)
!!$      write(aname,'(a,i3.3,a)') 'atmp-preh-',me,'.mtx'
!!$      call ain%print(fname=aname,head='atmp before haloTest ',iv=ilv)
!!$    end if
!!$    if (dump) then
!!$      call ain%cscnv(atmp,info)
!!$      call psb_gather(aglb,atmp,desc_a,info)
!!$      if (me==psb_root_) then
!!$        write(aname,'(a,i3.3,a)') 'aglob-prehalo.mtx'
!!$        call aglb%print(fname=aname,head='Test ')
!!$      end if
!!$    end if
!!$
!!$    !call psb_loc_to_glob(tmpcsr%ja,desc_a,info)
!!$    call atmp%mv_from(tmpcsr)
!!$
!!$    if (debug) then
!!$      write(aname,'(a,i3.3,a)') 'tmpcsr-',me,'.mtx'
!!$      call atmp%print(fname=aname,head='tmpcsr ',iv=ilv)
!!$      !call psb_set_debug_level(9999)
!!$    end if
!!$
!!$    ! FIXME THIS NEEDS REWORKING
!!$    if (debug) write(0,*) me,' Gtranspose into sphalo :',atmp%get_nrows(),atmp%get_ncols()
!!$    call psb_sphalo(atmp,desc_a,ahalo,info,rowscale=.true.)
!!$    if (debug) write(0,*) me,' Gtranspose from sphalo :',ahalo%get_nrows(),ahalo%get_ncols()
!!$    if (info == psb_success_) call psb_rwextd(ncol,atmp,info,b=ahalo)
!!$
!!$    if (debug) then
!!$      write(aname,'(a,i3.3,a)') 'ahalo-',me,'.mtx'
!!$      call ahalo%print(fname=aname,head='ahalo after haloTest ',iv=ilv)
!!$      write(aname,'(a,i3.3,a)') 'atmp-h-',me,'.mtx'
!!$      call atmp%print(fname=aname,head='atmp after haloTest ',iv=ilv)
!!$    end if
!!$
!!$    if (info == psb_success_) call ahalo%free()
!!$
!!$    call atmp%cp_to(tmpcoo)
!!$    call tmpcoo%transp()
!!$    !call psb_glob_to_loc(tmpcoo%ia,desc_a,info,iact='I')
!!$    if (debug) write(0,*) 'Before cleanup:',tmpcoo%get_nzeros()
!!$
!!$    j = 0
!!$    do k=1, tmpcoo%get_nzeros()
!!$      if ((tmpcoo%ia(k) > 0).and.(tmpcoo%ja(k)>0)) then
!!$        j = j+1
!!$        tmpcoo%ia(j)  = tmpcoo%ia(k)
!!$        tmpcoo%ja(j)  = tmpcoo%ja(k)
!!$        tmpcoo%val(j) = tmpcoo%val(k)
!!$      end if
!!$    end do
!!$    call tmpcoo%set_nzeros(j)
!!$
!!$    if (debug) write(0,*) 'After cleanup:',tmpcoo%get_nzeros()
!!$
!!$    call ahalo%mv_from(tmpcoo)
!!$    if (dump) then
!!$      call psb_gather(aglb,ahalo,desc_a,info)
!!$      if (me==psb_root_) then
!!$        write(aname,'(a,i3.3,a)') 'atran-preclip.mtx'
!!$        call aglb%print(fname=aname,head='Test ')
!!$      end if
!!$    end if
!!$
!!$
!!$    call ahalo%csclip(aout,info,imax=nrow)
!!$
!!$    if (debug) write(0,*) 'After clip:',aout%get_nzeros()
!!$
!!$    if (debug_sync) then
!!$      call psb_barrier(ictxt)
!!$      if (me == 0) write(0,*) 'End gtranspose '
!!$    end if
!!$    !call aout%cscnv(info,type='csr')
!!$
!!$    if (dump) then
!!$      write(aname,'(a,i3.3,a)') 'atran-',me,'.mtx'
!!$      call aout%print(fname=aname,head='atrans ',iv=ilv)
!!$      call psb_gather(aglb,aout,desc_a,info)
!!$      if (me==psb_root_) then
!!$        write(aname,'(a,i3.3,a)') 'atran.mtx'
!!$        call aglb%print(fname=aname,head='Test ')
!!$      end if
!!$    end if
!!$
!!$  end subroutine amg_dgtranspose
!!$
!!$  subroutine amg_dhtranspose(ain,aout,desc_a,info)
!!$    use psb_base_mod
!!$    implicit none
!!$    type(psb_ldspmat_type), intent(in)  :: ain
!!$    type(psb_ldspmat_type), intent(out) :: aout
!!$    type(psb_desc_type)           :: desc_a
!!$    integer(psb_ipk_), intent(out) :: info
!!$
!!$    !
!!$    ! BEWARE: This routine works under the assumption
!!$    ! that the same DESC_A works for both A and A^T, which
!!$    ! essentially means that A has a symmetric pattern.
!!$    !
!!$    type(psb_ldspmat_type) :: atmp, ahalo, aglb
!!$    type(psb_ld_coo_sparse_mat) :: tmpcoo, tmpc1, tmpc2, tmpch
!!$    type(psb_ld_csr_sparse_mat) :: tmpcsr
!!$    integer(psb_ipk_) :: nz1, nz2, nzh, nz
!!$    type(psb_ctxt_type) :: ictxt
!!$    integer(psb_ipk_) :: me, np
!!$    integer(psb_lpk_) :: i, j, k, nrow, ncol, nlz
!!$    integer(psb_lpk_), allocatable :: ilv(:)
!!$    character(len=80) :: aname
!!$    logical, parameter :: debug=.false., dump=.false., debug_sync=.false.
!!$
!!$    ictxt = desc_a%get_context()
!!$    call psb_info(ictxt,me,np)
!!$
!!$    nrow = desc_a%get_local_rows()
!!$    ncol = desc_a%get_local_cols()
!!$    if (debug_sync) then
!!$      call psb_barrier(ictxt)
!!$      if (me == 0) write(0,*) 'Start htranspose '
!!$    end if
!!$    call ain%cscnv(tmpcsr,info)
!!$
!!$    if (debug) then
!!$      ilv = [(i,i=1,ncol)]
!!$      call desc_a%l2gip(ilv,info,owned=.false.)
!!$      write(aname,'(a,i3.3,a)') 'atmp-preh-',me,'.mtx'
!!$      call ain%print(fname=aname,head='atmp before haloTest ',iv=ilv)
!!$    end if
!!$    if (dump) then
!!$      call ain%cscnv(atmp,info)
!!$      call psb_gather(aglb,atmp,desc_a,info)
!!$      if (me==psb_root_) then
!!$        write(aname,'(a,i3.3,a)') 'aglob-prehalo.mtx'
!!$        call aglb%print(fname=aname,head='Test ')
!!$      end if
!!$    end if
!!$
!!$    !call psb_loc_to_glob(tmpcsr%ja,desc_a,info)
!!$    call atmp%mv_from(tmpcsr)
!!$
!!$    if (debug) then
!!$      write(aname,'(a,i3.3,a)') 'tmpcsr-',me,'.mtx'
!!$      call atmp%print(fname=aname,head='tmpcsr ',iv=ilv)
!!$      !call psb_set_debug_level(9999)
!!$    end if
!!$
!!$    ! FIXME THIS NEEDS REWORKING
!!$    if (debug) write(0,*) me,' Htranspose into sphalo :',atmp%get_nrows(),atmp%get_ncols()
!!$    if (.true.) then
!!$      call psb_sphalo(atmp,desc_a,ahalo,info, outfmt='coo  ')
!!$      call atmp%mv_to(tmpc1)
!!$      call ahalo%mv_to(tmpch)
!!$      nz1 = tmpc1%get_nzeros()
!!$      call psb_loc_to_glob(tmpc1%ia(1:nz1),desc_a,info,iact='I')
!!$      call psb_loc_to_glob(tmpc1%ja(1:nz1),desc_a,info,iact='I')
!!$      nzh = tmpch%get_nzeros()
!!$      call psb_loc_to_glob(tmpch%ia(1:nzh),desc_a,info,iact='I')
!!$      call psb_loc_to_glob(tmpch%ja(1:nzh),desc_a,info,iact='I')
!!$      nlz = nz1+nzh
!!$      call tmpcoo%allocate(ncol,ncol,nlz)
!!$      tmpcoo%ia(1:nz1) = tmpc1%ia(1:nz1)
!!$      tmpcoo%ja(1:nz1) = tmpc1%ja(1:nz1)
!!$      tmpcoo%val(1:nz1) = tmpc1%val(1:nz1)
!!$      tmpcoo%ia(nz1+1:nz1+nzh) = tmpch%ia(1:nzh)
!!$      tmpcoo%ja(nz1+1:nz1+nzh) = tmpch%ja(1:nzh)
!!$      tmpcoo%val(nz1+1:nz1+nzh) = tmpch%val(1:nzh)
!!$      call tmpcoo%set_nzeros(nlz)
!!$      call tmpcoo%transp()
!!$      nz = tmpcoo%get_nzeros()
!!$      call psb_glob_to_loc(tmpcoo%ia(1:nz),desc_a,info,iact='I')
!!$      call psb_glob_to_loc(tmpcoo%ja(1:nz),desc_a,info,iact='I')
!!$      if (.true.) then
!!$        call tmpcoo%clean_negidx(info)
!!$      else
!!$        j = 0
!!$        do k=1, tmpcoo%get_nzeros()
!!$          if ((tmpcoo%ia(k) > 0).and.(tmpcoo%ja(k)>0)) then
!!$            j = j+1
!!$            tmpcoo%ia(j)  = tmpcoo%ia(k)
!!$            tmpcoo%ja(j)  = tmpcoo%ja(k)
!!$            tmpcoo%val(j) = tmpcoo%val(k)
!!$          end if
!!$        end do
!!$        call tmpcoo%set_nzeros(j)
!!$      end if
!!$      call ahalo%mv_from(tmpcoo)
!!$      call ahalo%csclip(aout,info,imax=nrow)
!!$
!!$    else
!!$      call psb_sphalo(atmp,desc_a,ahalo,info, rowscale=.true.)
!!$      if (debug) write(0,*) me,' Htranspose from sphalo :',ahalo%get_nrows(),ahalo%get_ncols()
!!$      if (info == psb_success_) call psb_rwextd(ncol,atmp,info,b=ahalo)
!!$
!!$      if (debug) then
!!$        write(aname,'(a,i3.3,a)') 'ahalo-',me,'.mtx'
!!$        call ahalo%print(fname=aname,head='ahalo after haloTest ',iv=ilv)
!!$        write(aname,'(a,i3.3,a)') 'atmp-h-',me,'.mtx'
!!$        call atmp%print(fname=aname,head='atmp after haloTest ',iv=ilv)
!!$      end if
!!$
!!$      if (info == psb_success_) call ahalo%free()
!!$
!!$      call atmp%cp_to(tmpcoo)
!!$      call tmpcoo%transp()
!!$      if (debug) write(0,*) 'Before cleanup:',tmpcoo%get_nzeros()
!!$      if (.true.) then
!!$        call tmpcoo%clean_negidx(info)
!!$      else
!!$
!!$        j = 0
!!$        do k=1, tmpcoo%get_nzeros()
!!$          if ((tmpcoo%ia(k) > 0).and.(tmpcoo%ja(k)>0)) then
!!$            j = j+1
!!$            tmpcoo%ia(j)  = tmpcoo%ia(k)
!!$            tmpcoo%ja(j)  = tmpcoo%ja(k)
!!$            tmpcoo%val(j) = tmpcoo%val(k)
!!$          end if
!!$        end do
!!$        call tmpcoo%set_nzeros(j)
!!$      end if
!!$
!!$      if (debug) write(0,*) 'After cleanup:',tmpcoo%get_nzeros()
!!$
!!$      call ahalo%mv_from(tmpcoo)
!!$      if (dump) then
!!$        call psb_gather(aglb,ahalo,desc_a,info)
!!$        if (me==psb_root_) then
!!$          write(aname,'(a,i3.3,a)') 'atran-preclip.mtx'
!!$          call aglb%print(fname=aname,head='Test ')
!!$        end if
!!$      end if
!!$
!!$
!!$      call ahalo%csclip(aout,info,imax=nrow)
!!$    end if
!!$
!!$    if (debug) write(0,*) 'After clip:',aout%get_nzeros()
!!$
!!$    if (debug_sync) then
!!$      call psb_barrier(ictxt)
!!$      if (me == 0) write(0,*) 'End htranspose '
!!$    end if
!!$    !call aout%cscnv(info,type='csr')
!!$
!!$    if (dump) then
!!$      write(aname,'(a,i3.3,a)') 'atran-',me,'.mtx'
!!$      call aout%print(fname=aname,head='atrans ',iv=ilv)
!!$      call psb_gather(aglb,aout,desc_a,info)
!!$      if (me==psb_root_) then
!!$        write(aname,'(a,i3.3,a)') 'atran.mtx'
!!$        call aglb%print(fname=aname,head='Test ')
!!$      end if
!!$    end if
!!$
!!$  end subroutine amg_dhtranspose
!!$
!!$  subroutine amg_dPMatchBox(nlver,nledge,verlocptr,verlocind,edgelocweight,&
!!$       & verdistance, mate, myrank, numprocs, ictxt,&
!!$       & msgindsent,msgactualsent,msgpercent,&
!!$       & ph0_time, ph1_time, ph2_time, ph1_card, ph2_card,info,display_inp)
!!$    use psb_base_mod
!!$    implicit none
!!$    type(psb_ctxt_type) :: ictxt
!!$    integer(psb_c_ipk_), value :: myrank, numprocs
!!$    integer(psb_c_lpk_), value :: nlver,nledge
!!$    integer(psb_c_lpk_) :: verlocptr(:),verlocind(:), verdistance(:)
!!$    integer(psb_c_lpk_) :: mate(:)
!!$    integer(psb_c_lpk_) :: msgindsent(*),msgactualsent(*)
!!$    real(c_double)      :: ph0_time, ph1_time, ph2_time
!!$    integer(psb_c_lpk_) :: ph1_card(*),ph2_card(*)
!!$    real(c_double)  :: edgelocweight(:)
!!$    real(c_double)      :: msgpercent(*)
!!$    integer(psb_ipk_)   :: info, me, np
!!$    integer(psb_c_mpk_) :: icomm, mrank, mnp
!!$    logical, optional   :: display_inp
!!$    !
!!$    logical, parameter :: debug=.false., debug_out=.false., debug_sync=.false., dump_input=.false.
!!$    logical            :: display_
!!$    integer(psb_lpk_) :: i,k
!!$    integer(psb_ipk_), save :: cnt=1
!!$
!!$    call psb_info(ictxt,me,np)
!!$    icomm = psb_get_mpi_comm(ictxt)
!!$    mrank = psb_get_mpi_rank(ictxt,me)
!!$    mnp   = np
!!$    if (present(display_inp)) then
!!$      display_ = display_inp
!!$    else
!!$      display_ = .false.
!!$    end if
!!$
!!$    verlocptr(:)   = verlocptr(:)  - 1
!!$    verlocind(:)   = verlocind(:) - 1
!!$    verdistance(:) = verdistance(:) -1
!!$
!!$    if (dump_input) then
!!$      block
!!$        integer(psb_ipk_) :: iout=20,info,i,j,k,nr
!!$        character(len=80) :: fname
!!$        write(fname,'(a,i4.4,a,i4.4,a)') 'verlocptr-l',cnt,'-i',me,'.mtx'
!!$        open(iout,file=fname,iostat=info)
!!$        if (info == 0) then
!!$          write(iout,'(a)') '%verlocptr '
!!$          write(iout,*) nlver
!!$          do i=1, nlver+1
!!$            write(iout,*) verlocptr(i)
!!$          end do
!!$          close(iout)
!!$        else
!!$          write(psb_err_unit,*) 'Error: could not open ',fname,' for output'
!!$        end if
!!$        write(fname,'(a,i4.4,a,i4.4,a)') 'edges-l',cnt,'-i',me,'.mtx'
!!$        open(iout,file=fname,iostat=info)
!!$        if (info == 0) then
!!$          write(iout,'(a)') '%verlocind/edgeweight '
!!$          write(iout,*) nlver
!!$          do i=1, nlver
!!$            do j=verlocptr(i)+1,verlocptr(i+1)
!!$              write(iout,*) i-1, verlocind(j),edgelocweight(j)
!!$            end do
!!$          end do
!!$          close(iout)
!!$        else
!!$          write(psb_err_unit,*) 'Error: could not open ',fname,' for output'
!!$        end if
!!$        if (me==0) then
!!$          write(fname,'(a,i4.4,a,i4.4,a)') 'verdistance-l',cnt,'-i',me,'.mtx'
!!$          open(iout,file=fname,iostat=info)
!!$          if (info == 0) then
!!$            write(iout,'(a)') '%verdistance'
!!$            write(iout,*) np
!!$            do i=1, np+1
!!$              write(iout,*) verdistance(i)
!!$            end do
!!$            close(iout)
!!$          else
!!$            write(psb_err_unit,*) 'Error: could not open ',fname,' for output'
!!$          end if
!!$        end if
!!$      end block
!!$      cnt = cnt + 1
!!$    end if
!!$
!!$    if (debug.or.display_) then
!!$      do i=0,np-1
!!$        if (me == i) then
!!$          write(6,*) 'Process: ',me,' :  Input into matching: nlver ',nlver,' nledge ',nledge
!!$          write(6,*) 'Process: ',me,' :  VERDISTANCE 0-base : ',verdistance(1:np+1)
!!$          write(6,*) 'Process: ',me,' :  VERLOCPTR   0-base : ',verlocptr(1:nlver+1)
!!$          write(6,*) 'Process: ',me,' :  VERLOCIND   0-base : ',verlocind(1:nledge)
!!$          write(6,*) 'Process: ',me,' :  EDGELOCWEIGHT      : ',edgelocweight(1:nledge)
!!$          write(6,*) 'Process: ',me,' :  Initial MATE       : ',mate(1:nlver)
!!$          flush(6)
!!$        end if
!!$        call psb_barrier(ictxt)
!!$      end do
!!$    end if
!!$    if (debug_sync) then
!!$      call psb_barrier(ictxt)
!!$      if (me == 0) write(0,*)' Calling Decmatch '
!!$    end if
!!$
!!$    call DecmatchC(nlver,nledge,verlocptr,verlocind,edgelocweight,&
!!$         & verdistance, mate, mrank, mnp, icomm,&
!!$         & msgindsent,msgactualsent,msgpercent,&
!!$         & ph0_time, ph1_time, ph2_time, ph1_card, ph2_card)
!!$    verlocptr(:)   = verlocptr(:)  + 1
!!$    verlocind(:)   = verlocind(:) + 1
!!$    verdistance(:) = verdistance(:) + 1
!!$
!!$    if (debug_sync) then
!!$      call psb_barrier(ictxt)
!!$      if (me == 0) write(0,*)' Done Decmatch '
!!$    end if
!!$
!!$    if (debug_out) then
!!$      do k=0,np-1
!!$        if (me == k) then
!!$          write(6,*) 'Process: ',me,' :  from Matching (0-base): ',info
!!$          do i=1,nlver
!!$            write(6,*) '(',i,',',mate(i),')'
!!$            !mate(i) = mate(i) +1
!!$            !
!!$          end do
!!$          flush(6)
!!$        end if
!!$        call psb_barrier(ictxt)
!!$      end do
!!$    end if
!!$    where(mate>=0) mate = mate + 1
!!$
!!$  end subroutine amg_dPMatchBox

end module amg_d_decmatch_mod