amg4psblas/mlprec/mld_dslu_bld.f90

!!$ 
!!$ 
!!$                           MLD2P4  version 1.0
!!$  MultiLevel Domain Decomposition Parallel Preconditioners Package
!!$             based on PSBLAS (Parallel Sparse BLAS version 2.2)
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!!$
!!$                      Salvatore Filippone  University of Rome Tor Vergata       
!!$                      Alfredo Buttari      University of Rome Tor Vergata
!!$                      Pasqua D'Ambra       ICAR-CNR, Naples
!!$                      Daniela di Serafino  Second University of Naples
!!$ 
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! File: mld_dslu_bld.f90
!
! Subroutine: mld_dslu_bld
! Version:    real
!
!  This routine computes the LU factorization of the local part of the matrix
!  stored into a, by using SuperLU. 
!  
!  The matrix to be factorized is
!  - either a submatrix of the distributed matrix corresponding to any level
!    of a multilevel preconditioner, and its factorization is used to build
!    the 'base preconditioner' corresponding to that level,
!  - or a copy of the whole matrix corresponding to the coarsest level of
!    a multilevel preconditioner, and its factorization is used to build
!    the 'base preconditioner' corresponding to the coarsest level.
!
!  The data structure allocated by SuperLU to store the L and U factors is
!  pointed by p%iprcparm(mld_slu_ptr_).
!
!
! Arguments:
!    a       -  type(psb_dspmat_type), input/output.
!               The sparse matrix structure containing the local submatrix to
!               be factorized.
!    desc_a  -  type(psb_desc_type), input.
!               The communication descriptor associated to a.
!    p       -  type(mld_dbaseprec_type), input/output.
!               The 'base preconditioner' data structure containing the pointer, 
!               p%iprcparm(mld_slu_ptr_), to the data structure used by SuperLU
!               to store the L and U factors.
!    info    -  integer, output.                                                             
!               Error code.
! 
subroutine mld_dslu_bld(a,desc_a,p,info)

  use psb_base_mod
  use mld_inner_mod, mld_protect_name => mld_dslu_bld

  implicit none 

  ! Arguments
  type(psb_dspmat_type), intent(inout)   :: a
  type(psb_desc_type), intent(in)        :: desc_a
  type(mld_dbaseprec_type), intent(inout) :: p
  integer, intent(out)                   :: info

  ! Local variables
  integer                  :: nzt,ictxt,me,np,err_act
  character(len=20)  :: name, ch_err

  if(psb_get_errstatus().ne.0) return 
  info=0
  name='mld_dslu_bld'
  call psb_erractionsave(err_act)

  ictxt = psb_cd_get_context(desc_a)

  call psb_info(ictxt, me, np)

  if (psb_toupper(a%fida) /= 'CSR') then 
    info=135
    call psb_errpush(info,name,a_err=a%fida)
    goto 9999
  endif

  nzt = psb_sp_get_nnzeros(a)
  !
  ! Compute the LU factorization
  !
  call mld_dslu_fact(a%m,nzt,&
       & a%aspk,a%ia2,a%ia1,p%iprcparm(mld_slu_ptr_),info)

  if (info /= 0) then
    ch_err='mld_slu_fact'
    call psb_errpush(4110,name,a_err=ch_err,i_err=(/info,0,0,0,0/))
    goto 9999
  end if

  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_dslu_bld