psblas3/base/serial/psb_sneigh.f90

!!$ 
!!$              Parallel Sparse BLAS  version 2.2
!!$    (C) Copyright 2006/2007/2008
!!$                       Salvatore Filippone    University of Rome Tor Vergata
!!$                       Alfredo Buttari        University of Rome Tor Vergata
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! File:  psb_sneigh.f90 
! Subroutine: 
! Arguments:

subroutine psb_sneigh(a,idx,neigh,n,info,lev)

  use psb_realloc_mod
  use psb_const_mod
  use psb_spmat_type
  use psb_serial_mod, psb_protect_name => psb_sneigh
  implicit none


  type(psb_sspmat_type), intent(in) :: a   ! the sparse matrix
  integer, intent(in)               :: idx ! the index whose neighbours we want to find
  integer, intent(out)              :: n, info   ! the number of neighbours and the info
  integer, allocatable              :: neigh(:) ! the neighbours
  integer, optional, intent(in)     :: lev ! level of neighbours to find

  integer :: lev_, i, nl, ifl,ill,&
       & n1, err_act, nn, nidx,ntl
  character(len=20)                 :: name
  integer, allocatable :: ia(:), ja(:)
  real(psb_spk_), allocatable :: val(:)

  name='psb_sneigh'
  info  = 0
  call psb_erractionsave(err_act)

  n    = 0
  info = 0
  if(present(lev)) then 
    lev_=lev
  else
    lev_=1
  end if

  call psb_sp_getrow(idx,a,n,ia,ja,val,info)
  if (info == 0) call psb_realloc(n,neigh,info)
  if (info /= 0) then 
    call psb_errpush(4000,name)
    goto 9999
  end if
  neigh(1:n) = ja(1:n)
  ifl = 1
  ill = n

  
  do nl = 2, lev_ 
    n1 = ill - ifl + 1
    call psb_ensure_size(ill+n1*n1,neigh,info)
    if (info /= 0) then 
      call psb_errpush(4000,name)
      goto 9999
    end if
    ntl = 0
    do i=ifl,ill
      nidx=neigh(i)
      if ((nidx /= idx).and.(nidx > 0).and.(nidx <= a%m)) then
        call psb_sp_getrow(nidx,a,nn,ia,ja,val,info)
        if (info==0) call psb_ensure_size(ill+ntl+nn,neigh,info)
        if (info /= 0) then 
          call psb_errpush(4000,name)
          goto 9999
        end if        
        neigh(ill+ntl+1:ill+ntl+nn)=ja(1:nn)
        ntl = ntl+nn
      end if
    end do
    call psb_msort_unique(neigh(ill+1:ill+ntl),nn)
    ifl = ill + 1
    ill = ill + nn
  end do
  call imsru(ill,neigh,psb_sort_up_,nn)
  n = nn

  call psb_erractionrestore(err_act)
  return
  
9999 continue
  call psb_erractionrestore(err_act)
  if (err_act == psb_act_abort_) then
     call psb_error()
     return
  end if
  return


end subroutine psb_sneigh