amg4psblas/mlprec/mld_dfact_bld.f90

!!$
!!$ 
!!$                                MLD2P4
!!$  MultiLevel Domain Decomposition Parallel Preconditioners Package
!!$             based on PSBLAS (Parallel Sparse BLAS v.2.0)
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!!$  (C) Copyright 2007  Alfredo Buttari      University of Rome Tor Vergata
!!$                      Pasqua D'Ambra       ICAR-CNR, Naples
!!$                      Daniela di Serafino  Second University of Naples
!!$                      Salvatore Filippone  University of Rome Tor Vergata
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! File: mld_dfact_bld.f90
!
! Subroutine: mld_dfact_bld
! Version:    real
!
!  This routine computes an LU or incomplete LU factorization of the input
!  matrix, according to the value of p%iprcparm(iprcparm(sub_solve_),
!  set by the user through mld_dprecinit or mld_dprecset.
!  It may also split the local matrix into its block-diagonal and
!  off block-diagonal parts, for the future application of multiple
!  block-Jacobi sweeps.
!
!  This routine is used by mld_dbaseprec_bld, to build a 'base' block-Jacobi or
!  Additive Schwarz (AS) preconditioner at any level of a multilevel preconditioner,
!  or a block-Jacobi or LU or ILU solver at the coarsest level of a multilevel
!  preconditioner. For the Additive Schwarz, it is called from mld_as_bld,
!  which prepares the overlap descriptor and retrieves the remote rows into blck.
!
!  More precisely, the routine  performs one of the following tasks: 
!
!  1. construction of a block-Jacobi preconditioner associated
!     to a matrix A distributed among the processes (allowed at any level);
!
!  2. setup of block-Jacobi sweeps to compute an approximate solution of a
!     linear system
!                                    A*Y = X,
!     distributed among the processes (allowed only at the coarsest level);
!
!  3. LU factorization of a linear system
!                                    A*Y = X,
!     distributed among the processes (allowed only at the coarsest level);
!
!  4. LU or incomplete LU factorization of a linear system
!                                    A*Y = X,
!     replicated on the processes (allowed only at the coarsest level).
!
!  The following factorizations are available:
!  - ILU(k), i.e. ILU factorization with fill-in level k;
!  - MILU(k), i.e. modified ILU factorization with fill-in level k;
!  - ILU(k,t), i.e. ILU with threshold (i.e. drop tolerance) t and k additional
!    entries in each row of the L and U factors with respect to the initial
!    sparsity pattern;
!  - serial LU implemented in SuperLU version 3.0;
!  - serial LU implemented in UMFPACK version 4.4;
!  - distributed LU implemented in SuperLU_DIST version 2.0.
!
!  
! Arguments:
!    a       -  type(psb_dspmat_type), input.
!               The sparse matrix structure containing the local part of the
!               matrix to be preconditioned or factorized.
!    p       -  type(mld_dbaseprec_type), input/output.
!               The 'base preconditioner' data structure containing the local 
!               part of the preconditioner or solver at the current level.
!    info    -  integer, output.
!               Error code.              
!    upd     -  character, input.
!               If upd='F' then the preconditioner is built from scratch;
!               if upd=T' then the matrix to be preconditioned has the same
!               sparsity pattern of a matrix that has been previously
!               preconditioned, hence some information is reused in building
!               the new preconditioner.
!    blck    -  type(psb_dspmat_type), input, optional.
!               The sparse matrix structure containing the remote rows of the
!               matrix to be factorized, that have been retrieved by mld_as_bld
!               to build an Additive Schwarz base preconditioner with overlap
!               greater than 0. If the overlap is 0 blck is empty.
!  
subroutine mld_dfact_bld(a,p,upd,info,blck)

  use psb_base_mod
  use mld_prec_mod, mld_protect_name => mld_dfact_bld

  implicit none

  ! Arguments
  type(psb_dspmat_type), intent(in), target :: a
  type(mld_dbaseprc_type), intent(inout)    :: p
  integer, intent(out)                      :: info
  character, intent(in)                     :: upd
  type(psb_dspmat_type), intent(in), target, optional  :: blck

  ! Local Variables                         
  type(psb_dspmat_type), pointer :: blck_
  type(psb_dspmat_type)          :: atmp
  integer                        :: ictxt,np,me,err_act
  integer                        :: debug_level, debug_unit
  integer                        :: k, m, int_err(5), n_row, nrow_a, n_col
  character                      :: trans, unitd
  character(len=20)              :: name, ch_err

  if(psb_get_errstatus().ne.0) return 
  info=0
  name='mld_dfact_bld'
  call psb_erractionsave(err_act)
  debug_unit  = psb_get_debug_unit()
  debug_level = psb_get_debug_level()
  ictxt       = psb_cd_get_context(p%desc_data)
  call psb_info(ictxt, me, np)

  m = a%m
  if (m < 0) then
    info = 10
    int_err(1) = 1
    int_err(2) = m
    call psb_errpush(info,name,i_err=int_err)
    goto 9999
  endif
  trans = 'N'
  unitd = 'U'

  if (present(blck)) then 
    blck_ => blck
  else
    allocate(blck_,stat=info)
    if (info ==0) call psb_sp_all(0,0,blck_,1,info)
    if(info /= 0) then
      info=4010
      ch_err='psb_sp_all'
      call psb_errpush(info,name,a_err=ch_err)
      goto 9999
    end if
    blck_%fida            = 'COO'
    blck_%infoa(psb_nnz_) = 0
  end if
  call psb_nullify_sp(atmp)

  !
  ! Treat separately the case the local matrix has to be reordered
  ! and the case this is not required.
  !
  select case(p%iprcparm(mld_sub_ren_)) 

    !
    ! A reordering of the local matrix is required.
    !
  case (1:)

    !
    ! Reorder the rows and the columns of the local extended matrix,
    ! according to the value of p%iprcparm(sub_ren_). The reordered 
    ! matrix is stored into atmp, using the COO format.
    !
    call  mld_sp_renum(a,blck_,p,atmp,info)
    if (info/=0) then
      call psb_errpush(4010,name,a_err='mld_sp_renum')
      goto 9999
    end if

    !
    ! Clip into p%av(ap_nd_) the off block-diagonal part of the local
    ! matrix. The clipped matrix is then stored in CSR format.
    !
    if (p%iprcparm(mld_smooth_sweeps_) > 1) then 
      call psb_sp_clip(atmp,p%av(mld_ap_nd_),info,&
           & jmin=atmp%m+1,rscale=.false.,cscale=.false.)
      if (info == 0) call psb_spcnv(p%av(mld_ap_nd_),info,&
           & afmt='csr',dupl=psb_dupl_add_)
      if (info /= 0) then
        call psb_errpush(4010,name,a_err='psb_spcnv')
        goto 9999
      end if
      
      k = psb_sp_get_nnzeros(p%av(mld_ap_nd_))
      call psb_sum(ictxt,k)
      
      if (k == 0) then
        ! 
        ! If the off diagonal part is emtpy, there is no point in doing
        ! multiple Jacobi sweeps. This is certain to happen when running
        ! on a single processor.
        !
        p%iprcparm(mld_smooth_sweeps_) = 1
      end if
    end if
    if (debug_level >= psb_debug_outer_) &
         & write(debug_unit,*) me,' ',trim(name),' Factoring rows ',&
         & atmp%m,a%m,blck_%m,atmp%ia2(atmp%m+1)-1

    ! 
    ! Compute a factorization of the diagonal block of the local matrix,
    ! according to the choice made by the user by setting p%iprcparm(sub_solve_)
    !
    select case(p%iprcparm(mld_sub_solve_))

    case(mld_ilu_n_,mld_milu_n_,mld_ilu_t_) 
      !
      ! ILU(k)/MILU(k)/ILU(k,t) factorization.
      !      
      call psb_spcnv(atmp,info,afmt='csr',dupl=psb_dupl_add_)
      if (info == 0) call mld_ilu_bld(atmp,p,upd,info)
      if (info/=0) then
        call psb_errpush(4010,name,a_err='mld_ilu_bld')
        goto 9999
      end if

    case(mld_slu_)
      !
      ! LU factorization through the SuperLU package.
      !
      call psb_spcnv(atmp,info,afmt='csr',dupl=psb_dupl_add_)
      if (info == 0) call mld_slu_bld(atmp,p%desc_data,p,info)
      if (info /= 0) then
        call psb_errpush(4010,name,a_err='mld_slu_bld')
        goto 9999
      end if

    case(mld_sludist_)
      !
      ! LU factorization through the SuperLU_DIST package. This works only
      ! when the matrix is distributed among the processes.
      ! NOTE: Should have NO overlap here!!!!   
      !
      call psb_spcnv(a,atmp,info,afmt='csr')
      if (info == 0) call mld_sludist_bld(atmp,p%desc_data,p,info)
      if (info /= 0) then
        call psb_errpush(4010,name,a_err='mld_sludist_bld')
        goto 9999
      end if

    case(mld_umf_)
      !
      ! LU factorization through the UMFPACK package.
      !
      call psb_spcnv(atmp,info,afmt='csc',dupl=psb_dupl_add_)
      if (info == 0) call mld_umf_bld(atmp,p%desc_data,p,info)
      if (info /= 0) then
        call psb_errpush(4010,name,a_err='mld_umf_bld')
        goto 9999
      end if

    case(mld_f_none_) 
      !
      ! Error: no factorization required.
      !
      info=4001
      call psb_errpush(info,name,a_err='Inconsistent prec  mld_f_none_')
      goto 9999

    case default
      info=4001
      call psb_errpush(info,name,a_err='Unknown mld_sub_solve_')
      goto 9999
    end select

    call psb_sp_free(atmp,info) 

    if (info/=0) then
      call psb_errpush(4010,name,a_err='psb_sp_free')
      goto 9999
    end if

    !
    ! No reordering of the local matrix is required
    !
  case(0)


    !
    ! In case of multiple block-Jacobi sweeps, clip into p%av(ap_nd_)
    ! the off block-diagonal part of the local extended matrix. The
    ! clipped matrix is then stored in CSR format.
    !
    
    if (p%iprcparm(mld_smooth_sweeps_) > 1) then 
      n_row = psb_cd_get_local_rows(p%desc_data)
      n_col = psb_cd_get_local_cols(p%desc_data)
      nrow_a = a%m 
      ! The following is known to work 
      ! given that the output from CLIP is in COO. 
      call psb_sp_clip(a,p%av(mld_ap_nd_),info,&
           & jmin=nrow_a+1,rscale=.false.,cscale=.false.)
      if (info == 0) call psb_sp_clip(blck_,atmp,info,&
           & jmin=nrow_a+1,rscale=.false.,cscale=.false.)
      if (info == 0) call psb_rwextd(n_row,p%av(mld_ap_nd_),info,b=atmp) 
      if (info == 0) call psb_spcnv(p%av(mld_ap_nd_),info,&
           & afmt='csr',dupl=psb_dupl_add_)
      if (info /= 0) then
        call psb_errpush(4010,name,a_err='clip & psb_spcnv csr 4')
        goto 9999
      end if
      
      k = psb_sp_get_nnzeros(p%av(mld_ap_nd_))
      call psb_sum(ictxt,k)
      
      if (k == 0) then 
        !
        ! If the off block-diagonal part is emtpy, there is no point in doing
        ! multiple Jacobi sweeps. This is certain to happen when running
        ! on a single processor.
        !
        p%iprcparm(mld_smooth_sweeps_) = 1
      end if
      call psb_sp_free(atmp,info) 
      if (info/=0) then
        call psb_errpush(4010,name,a_err='psb_sp_free')
        goto 9999
      end if
    end if

    ! 
    ! Compute a factorization of the diagonal block of the local matrix,
    ! according to the choice made by the user by setting p%iprcparm(sub_solve_)
    !
    select case(p%iprcparm(mld_sub_solve_))

    case(mld_ilu_n_,mld_milu_n_,mld_ilu_t_) 
      !
      ! ILU(k)/MILU(k)/ILU(k,t) factorization.
      !
      !
      ! Compute the incomplete LU factorization.
      !
      call mld_ilu_bld(a,p,upd,info,blck=blck_)
      if (info/=0) then
        call psb_errpush(4010,name,a_err='mld_ilu_bld')
        goto 9999
      end if

    case(mld_slu_)
      !
      ! LU factorization through the SuperLU package.
      ! 
      n_row = psb_cd_get_local_rows(p%desc_data)
      n_col = psb_cd_get_local_cols(p%desc_data)
      call psb_spcnv(a,atmp,info,afmt='coo')
      if (info == 0) call psb_rwextd(n_row,atmp,info,b=blck_) 

      !
      ! Compute the LU factorization.
      !
      if (info == 0) call psb_spcnv(atmp,info,afmt='csr',dupl=psb_dupl_add_)
      if (info == 0) call mld_slu_bld(atmp,p%desc_data,p,info)
      if (info /= 0) then
        call psb_errpush(4010,name,a_err='mld_slu_bld')
        goto 9999
      end if

      call psb_sp_free(atmp,info) 
      if (info/=0) then
        call psb_errpush(4010,name,a_err='psb_sp_free')
        goto 9999
      end if

    case(mld_sludist_)
      !
      ! LU factorization through the SuperLU_DIST package. This works only
      ! when the matrix is distributed among the processes.
      ! NOTE: Should have NO overlap here!!!!   
      !
      call psb_spcnv(a,atmp,info,afmt='csr')
      if (info == 0) call mld_sludist_bld(atmp,p%desc_data,p,info)
      if (info /= 0) then
        call psb_errpush(4010,name,a_err='mld_sludist_bld')
        goto 9999
      end if

      call psb_sp_free(atmp,info) 
      if (info/=0) then
        call psb_errpush(4010,name,a_err='psb_sp_free')
        goto 9999
      end if

    case(mld_umf_)
      !
      ! LU factorization through the UMFPACK package.
      !

      call psb_spcnv(a,atmp,info,afmt='coo')
      if (info /= 0) then
        call psb_errpush(4010,name,a_err='psb_spcnv')
        goto 9999
      end if

      n_row = psb_cd_get_local_rows(p%desc_data)
      n_col = psb_cd_get_local_cols(p%desc_data)
      call psb_rwextd(n_row,atmp,info,b=blck_) 

      !
      ! Compute the LU factorization.
      !
      if (info == 0) call psb_spcnv(atmp,info,afmt='csc',dupl=psb_dupl_add_)
      if (info == 0) call mld_umf_bld(atmp,p%desc_data,p,info)
      if (debug_level >= psb_debug_outer_) &
           & write(debug_unit,*) me,' ',trim(name),&
           & ': Done mld_umf_bld ',info
      if (info /= 0) then
        call psb_errpush(4010,name,a_err='mld_umf_bld')
        goto 9999
      end if

      call psb_sp_free(atmp,info) 
      if (info/=0) then
        call psb_errpush(4010,name,a_err='psb_sp_free')
        goto 9999
      end if

    case(mld_f_none_) 
      !
      ! Error: no factorization required.
      !
      info=4001
      call psb_errpush(info,name,a_err='Inconsistent prec  mld_f_none_')
      goto 9999

    case default
      info=4001
      call psb_errpush(info,name,a_err='Unknown mld_sub_solve_')
      goto 9999
    end select

  case default
    info=4001
    call psb_errpush(info,name,a_err='Invalid renum_')
    goto 9999
  end select
  
  if (.not.present(blck)) then 
    call psb_sp_free(blck_,info)
    if (info == 0) deallocate(blck_)
    if (info /= 0) then
      call psb_errpush(4010,name,a_err='psb_sp_free')
      goto 9999
    end if
  end if

  if (debug_level >= psb_debug_outer_) &
       & write(debug_unit,*) me,' ',trim(name),'End '

  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_dfact_bld