subroutine MATRIX_VECTOR &
   (ifile_in,name_in,NENS_START,NENS,MPIRANK,NPROC,jsta,jend,N_1,x,sum_loc)
!**********************************************************************
! *          
! * ABSTRACT: MATRIX * VECTOR product 
! *           (N_1 x NENS) * (NENS) = (N_1)
! *
! * 09/01/2003    ..... M. ZUPANSKI:
! *
! **********************************************************************
!-----
     integer :: ifile_in
     integer :: NENS,NENS_START
     integer :: N_1
     integer :: NPROC,MPIRANK
     integer :: jsta,jend
     character*20 :: name_in
     character*30 :: filein
     real,dimension(1:N_1) :: sum_loc
     real,dimension(NENS_START:NENS)  :: x
     integer :: NN

     real,allocatable :: x_in(:)

!=========================================================
        if(MPIRANK.eq.0) then
        write(*,*) "start MATRIX_VECTOR"
        end if

  100 format(A,i4.4)

      allocate(x_in(1:N_1))

!==============start calculation===================

      sum_loc(:)=0.0
      ii=0
       do jj=jsta,jend
      ii=ii+1

         write(filein,100) trim(name_in),jj

      CLOSE(ifile_in)
      OPEN(UNIT=ifile_in,FILE=filein,FORM='UNFORMATTED',IOSTAT=IER)
      IF(IER.NE.0) WRITE(*,*) ifile_in,' OPEN UNIT ERROR IER=',IER
      READ(ifile_in) NN
      if(NN.ne.N_1) then
      write(*,*) "MATRIX_VECTOR: PROBLEM WITH DIMENSIONS NN=",NN," N_1=",N_1
      end if
      READ(ifile_in) x_in
      CLOSE(ifile_in,STATUS='KEEP')

       do m=1,N_1
       sum_loc(m)=sum_loc(m)+x_in(m)*x(jj)
       end do

       end do       !jj

      deallocate(x_in)

        if(MPIRANK.eq.0) then
        write(*,*) "end MATRIX_VECTOR"
        end if

            return
            end subroutine MATRIX_VECTOR