Telluride Matrix-Vector Multiplication Routine for Nonorthogonal Operator

SUBROUTINE Y_EQ_AX_PROJECTION (nunk, X, Y, status)

  [snip]
  type(JT_vector_type), intent(in) :: X
  [snip]

  ! Compute a vertex-averaged solution and gather it.
  call VERTEX_AVG (X%Values, Solution_Vtx, BOUNDARY=X%Aux2)
  call EN_GATHER (Solution_Vertex, Solution_Vtx, BOUNDARY=X%Aux3)

  ! Gather the solution from element neighbors.
  call EE_GATHER (Solution_Ngbr, X%Values, BOUNDARY=X%Aux1)

  ! Loop over faces, accumulating the product
  ! (Face_Area/Rho_Face)*(Grad_X*Face_Normal).
  Y = zero
  do f = 1,nfc

     ! Get the face solution gradient.
     call FACE_GRADIENT (..., X%Values, ...)

     ! Dot the solution gradient with the face unit normal.
     N_Dot_Grad_X = zero
     do n = 1,ndim
        N_Dot_Grad_X = N_Dot_Grad_X + Grad_X(n,:)*Cell%Face_Normal(n,f)
     end do

     [snip]

     ! Accumulate the contribution for this face.
     Y = Y + Coeff(f,:)*N_Dot_Grad_X
  end do

  return
END SUBROUTINE Y_EQ_AX_PROJECTION