PRACE NPT

      Subroutine sym7pol( n1, n2, n3, m, mp, a, al, rmr, x, y, gamma )

! ---------------------------------------------------------------------

! --- Polynomial (Neumann) preconditioner.

! ---------------------------------------------------------------------

      Use         numerics

      Use         floptime

      Use         mpi_module

      Implicit    None

      Integer  :: n1, n2, n3, m, mp

      Real(l_) :: a(m,0:3), al(m,1:3), x(n1*n2*n3), y(n1*n2*n3)

      Real(l_) :: gamma(mp+1)

      Real(l_) :: rmr

      Real(l_) :: w(n1*n2*n3)

      Integer  :: i

      Real(l_) :: nrm2

      External    nrm2

! ---------------------------------------------------------------------

      y(lb:gub) = gamma(mp+1)*x(lb:gub)

      Do i = 1, mp

         Call sym7mxv( n1, n2, n3, m, a, al, y, w )

         y(lb:gub) = y(lb:gub) - w(lb:gub)

         y(lb:gub) = y(lb:gub) + gamma(mp-i+1)*x(lb:gub)

      End Do

! ---------------------------------------------------------------------

! --- Computation of (r,Mr) where M is the preconditioner.

      rmr = nrm2( m, y(lb) )

      flops = flops + m*( 1 + 3*mp )

! ---------------------------------------------------------------------

      End Subroutine sym7pol