amg4psblas/mlprec/mld_zbaseprec_aply.f90

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!!$ 
!!$                                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_zbaseprec_aply.f90.
!
! Subroutine: mld_zbaseprec_aply.
! Version:    complex.
!
!  This routine applies a base preconditioner by computing
!
!                          Y = beta*Y + alpha*op(K^(-1))*X,
!  where
!  - K is the base preconditioner, stored in prec,
!  - op(K^(-1)) is K^(-1) or its transpose, according to the value of trans,
!  - X and Y are vectors,
!  - alpha and beta are scalars.
!
!  The routine is used by mld_dmlprec_aply, to apply the multilevel preconditioners,
!  or directly by mld_dprec_aply, to apply the basic one-level preconditioners (diagonal,
!  block-Jacobi or additive Schwarz), or to have no preconditioning.
!
!
! Arguments:
!   alpha      -  complex(kind(0.d0)), input.
!                 The scalar alpha.
!   prec       -  type(<mld_zbaseprc_type>), input.
!                 The base preconditioner data structure containing the local part
!                 of the preconditioner K.
!   x          -  complex(kind(0.d0)), dimension(:), input.
!                 The local part of the vector X.
!   beta       -  complex(kind(0.d0)), input.
!                 The scalar beta.
!   y          -  complex(kind(0.d0)), dimension(:), input/output.
!                 The local part of the vector Y.
!   desc_data  -  type(<psb_desc_type>), input.
!                 The communication descriptor associated to the matrix to be
!                 preconditioned.
!   trans      -  character, optional.
!                 If trans='N','n' then op(K^(-1)) = K^(-1);
!                 if trans='T','t' then op(K^(-1)) = K^(-T) (transpose of K^(-1)).
!   work       -  real(kind(0.d0)), dimension (:), optional, target.
!                 Workspace. Its size must be at least 4*psb_cd_get_local_cols(desc_data).
!   info       -  integer, output.
!                 Error code.
!  
subroutine mld_zbaseprec_aply(alpha,prec,x,beta,y,desc_data,trans,work,info)

  use psb_base_mod
  use mld_prec_mod, mld_protect_name => mld_zbaseprec_aply

  implicit none 

! Arguments
  type(psb_desc_type),intent(in)      :: desc_data
  type(mld_zbaseprc_type), intent(in) :: prec
  complex(kind(0.d0)),intent(in)      :: x(:)
  complex(kind(0.d0)),intent(inout)   :: y(:)
  complex(kind(0.d0)),intent(in)      :: alpha,beta
  character(len=1)                    :: trans
  complex(kind(0.d0)),target          :: work(:)
  integer, intent(out)                :: info

  ! Local variables
  integer :: n_row,n_col, int_err(5), nrow_d
  complex(kind(1.d0)), pointer :: ww(:), aux(:), tx(:),ty(:)
  character     ::diagl, diagu
  integer :: ictxt,np,me, isz, err_act
  logical,parameter                 :: debug=.false., debugprt=.false.
  character(len=20)   :: name, ch_err
  
  name='mld_zbaseprec_aply'
  info = 0
  call psb_erractionsave(err_act)

  ictxt = psb_cd_get_context(desc_data)

  call psb_info(ictxt, me, np)

  diagl='U'
  diagu='U'

  select case(trans)
  case('N','n')
  case('T','t','C','c')
  case default
     info=40
     int_err(1)=6
     ch_err(2:2)=trans
     goto 9999
  end select

  select case(prec%iprcparm(mld_prec_type_))

  case(mld_noprec_)
  !
  ! No preconditioner
  !

    call psb_geaxpby(alpha,x,beta,y,desc_data,info)

  case(mld_diag_)
  !
  ! Diagonal preconditioner
  !
    
    if (size(work) >= size(x)) then 
      ww => work
    else
      allocate(ww(size(x)),stat=info)
      if (info /= 0) then 
        call psb_errpush(4025,name,i_err=(/size(x),0,0,0,0/),a_err='complex(kind(1.d0))')
        goto 9999      
      end if
    end if

    n_row = psb_cd_get_local_rows(desc_data)
    ww(1:n_row) = x(1:n_row)*prec%d(1:n_row)
    call psb_geaxpby(alpha,ww,beta,y,desc_data,info)

    if (size(work) < size(x)) then 
      deallocate(ww,stat=info)
      if (info /= 0) then 
        call psb_errpush(4010,name,a_err='Deallocate')
        goto 9999      
      end if
    end if

  case(mld_bjac_)
  !
  ! Block-Jacobi preconditioner
  !

    call mld_bjac_aply(alpha,prec,x,beta,y,desc_data,trans,work,info)
    if(info.ne.0) then
       info=4010
       ch_err='mld_bjac_aply'
       goto 9999
    end if

  case(mld_as_)
  !
  ! Additive Schwarz preconditioner
  !

    if (prec%iprcparm(mld_n_ovr_)==0) then
      ! 
      ! shortcut: this fixes performance for RAS(0) == BJA
      !
      call mld_bjac_aply(alpha,prec,x,beta,y,desc_data,trans,work,info)
      if(info.ne.0) then
        info=4010
        ch_err='psb_bjacaply'
        goto 9999
      end if

    else

      !
      ! Note: currently trans is unused
      !

      n_row  = psb_cd_get_local_rows(prec%desc_data)
      n_col  = psb_cd_get_local_cols(prec%desc_data)
      nrow_d = psb_cd_get_local_rows(desc_data)
      isz=max(n_row,N_COL)
      if ((6*isz) <= size(work)) then 
        ww => work(1:isz)
        tx => work(isz+1:2*isz)
        ty => work(2*isz+1:3*isz)
        aux => work(3*isz+1:)
      else if ((4*isz) <= size(work)) then 
        aux => work(1:)
        allocate(ww(isz),tx(isz),ty(isz),stat=info)
        if (info /= 0) then 
          call psb_errpush(4025,name,i_err=(/3*isz,0,0,0,0/),&
               & a_err='complex(kind(1.d0))')
          goto 9999      
        end if
      else if ((3*isz) <= size(work)) then 
        ww => work(1:isz)
        tx => work(isz+1:2*isz)
        ty => work(2*isz+1:3*isz)
        allocate(aux(4*isz),stat=info)
        if (info /= 0) then 
          call psb_errpush(4025,name,i_err=(/4*isz,0,0,0,0/),&
               & a_err='complex(kind(1.d0))')
          goto 9999      
        end if
      else 
        allocate(ww(isz),tx(isz),ty(isz),&
             &aux(4*isz),stat=info)
        if (info /= 0) then 
          call psb_errpush(4025,name,i_err=(/4*isz,0,0,0,0/),&
               & a_err='complex(kind(1.d0))')
          goto 9999      
        end if

      endif

      if (debugprt) write(0,*)' vdiag: ',prec%d(:)
      if (debug) write(0,*) 'Bi-CGSTAB with Additive Schwarz prec' 

      tx(1:nrow_d)     = x(1:nrow_d) 
      tx(nrow_d+1:isz) = zzero

      !
      ! Get the overlap entries of tx (tx==x)
      ! 
        if (prec%iprcparm(mld_sub_restr_)==psb_halo_) then 
        call psb_halo(tx,prec%desc_data,info,work=aux,data=psb_comm_ext_)
        if(info /=0) then
          info=4010
          ch_err='psb_halo'
          goto 9999
        end if
      else if (prec%iprcparm(mld_sub_restr_) /= psb_none_) then 
        write(0,*) 'Problem in PREC_APLY: Unknown value for restriction ',&
             &prec%iprcparm(mld_sub_restr_)
      end if

      !
      ! If required, reorder tx according to the row/column permutation of the
      ! local extended matrix, stored into the permutation vector prec%perm
      !
      if (prec%iprcparm(mld_sub_ren_)>0) then 
        call psb_gelp('n',prec%perm,tx,info)
        if(info /=0) then
          info=4010
          ch_err='psb_gelp'
          goto 9999
        end if
      endif

      !
      ! Apply to tx the block-Jacobi preconditioner/solver (multiple sweeps of the
      ! block-Jacobi solver can be applied at the coarsest level of a multilevel
      ! preconditioner). The resulting vector is ty.
      !
      call mld_bjac_aply(zone,prec,tx,zzero,ty,prec%desc_data,trans,aux,info)
      if(info.ne.0) then
        info=4010
        ch_err='mld_bjac_aply'
        goto 9999
      end if

      !
      ! Apply to ty the inverse permutation of prec%perm
      !
      if (prec%iprcparm(mld_sub_ren_)>0) then 
        call psb_gelp('n',prec%invperm,ty,info)
        if(info /=0) then
          info=4010
          ch_err='psb_gelp'
          goto 9999
        end if
      endif

      select case (prec%iprcparm(mld_sub_prol_)) 

      case(psb_none_)
        ! 
        ! Would work anyway, but since it is supposed to do nothing ...
        ! call f90_psovrl(ty,prec%desc_data,update=prec%a_restrict)
        !

      case(psb_sum_,psb_avg_) 
        !
        ! Update the overlap of ty
        !
        call psb_ovrl(ty,prec%desc_data,info,&
             & update=prec%iprcparm(mld_sub_prol_),work=aux)
        if(info /=0) then
          info=4010
          ch_err='psb_ovrl'
          goto 9999
        end if

      case default
        write(0,*) 'Problem in PREC_APLY: Unknown value for prolongation ',&
             & prec%iprcparm(mld_sub_prol_)
      end select

      !
      ! Compute y = beta*y + alpha*ty (ty==K^(-1)*tx)
      !
      call psb_geaxpby(alpha,ty,beta,y,desc_data,info) 


      if ((6*isz) <= size(work)) then 
      else if ((4*isz) <= size(work)) then 
        deallocate(ww,tx,ty)
      else if ((3*isz) <= size(work)) then 
        deallocate(aux)
      else 
        deallocate(ww,aux,tx,ty)
      endif
    end if

  case default
    write(0,*) 'Invalid PRE%PREC ',prec%iprcparm(mld_prec_type_),':',&
         & mld_min_prec_,mld_noprec_,mld_diag_,mld_bjac_,mld_as_
  
  end select

  call psb_erractionrestore(err_act)
  return

9999 continue
  call psb_errpush(info,name,i_err=int_err,a_err=ch_err)
  call psb_erractionrestore(err_act)
  if (err_act.eq.psb_act_abort_) then
    call psb_error()
    return
  end if
  return

end subroutine mld_zbaseprec_aply