PRACE NPT

      Subroutine checkreg( n1, n2, n3, a, b, x, maxdf, mindf )

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

      Use       numerics

      Implicit None

      Integer  :: n1, n2, n3

      Real(l_) :: a(n1*n2*n3,0:3), b(n1*n2*n3), x(n1*n2*n3)

      Real(l_) :: maxdf, mindf

      Real(l_) :: y(n1*n2*n3), r(n1*n2*n3)

      Real(l_) :: nrm2

      External :: nrm2

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

      Call sym7mxv( n1, n2, n3, a, x, y )

      r = b - y

      PRINT *, 'Check L2 norm = ', Sqrt( nrm2( n1*n2*3, r ) )

      maxdf = Maxval( r )

      mindf = Minval( r )

      PRINT 1000, r

 1000 Format( 5g13.5 )

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

      End Subroutine checkreg