!--------------------------------------------------------------------------
   !---------------------------- scalar_laplacian ----------------------------------
   !$OMP DO SCHEDULE(STATIC)
   DO edge = 1, edge_num
      ij_left = left(edge)
      ij_right = right(edge)
      !DIR$ SIMD
      DO l = 1, llm
         grad(l,edge) = 1.*(b(l,ij_right)-b(l,ij_left))
      END DO
   END DO
   !$OMP END DO
   !$OMP DO SCHEDULE(STATIC)
   DO ij = 1, primal_num
      ! this VLOOP iterates over primal cell edges
      SELECT CASE(primal_deg(ij))
      CASE(4)
         edge1 = primal_edge(1,ij)
         edge2 = primal_edge(2,ij)
         edge3 = primal_edge(3,ij)
         edge4 = primal_edge(4,ij)
         le_de1 = le_de(edge1)
         le_de2 = le_de(edge2)
         le_de3 = le_de(edge3)
         le_de4 = le_de(edge4)
         sign1 = primal_ne(1,ij)
         sign2 = primal_ne(2,ij)
         sign3 = primal_ne(3,ij)
         sign4 = primal_ne(4,ij)
         !DIR$ SIMD
         DO l = 1, llm
            div_ij=0.
            div_ij = div_ij + sign1*le_de1*grad(l,edge1)
            div_ij = div_ij + sign2*le_de2*grad(l,edge2)
            div_ij = div_ij + sign3*le_de3*grad(l,edge3)
            div_ij = div_ij + sign4*le_de4*grad(l,edge4)
            divu(l,ij) = div_ij / Ai(ij)
         END DO
      CASE(5)
         edge1 = primal_edge(1,ij)
         edge2 = primal_edge(2,ij)
         edge3 = primal_edge(3,ij)
         edge4 = primal_edge(4,ij)
         edge5 = primal_edge(5,ij)
         le_de1 = le_de(edge1)
         le_de2 = le_de(edge2)
         le_de3 = le_de(edge3)
         le_de4 = le_de(edge4)
         le_de5 = le_de(edge5)
         sign1 = primal_ne(1,ij)
         sign2 = primal_ne(2,ij)
         sign3 = primal_ne(3,ij)
         sign4 = primal_ne(4,ij)
         sign5 = primal_ne(5,ij)
         !DIR$ SIMD
         DO l = 1, llm
            div_ij=0.
            div_ij = div_ij + sign1*le_de1*grad(l,edge1)
            div_ij = div_ij + sign2*le_de2*grad(l,edge2)
            div_ij = div_ij + sign3*le_de3*grad(l,edge3)
            div_ij = div_ij + sign4*le_de4*grad(l,edge4)
            div_ij = div_ij + sign5*le_de5*grad(l,edge5)
            divu(l,ij) = div_ij / Ai(ij)
         END DO
      CASE(6)
         edge1 = primal_edge(1,ij)
         edge2 = primal_edge(2,ij)
         edge3 = primal_edge(3,ij)
         edge4 = primal_edge(4,ij)
         edge5 = primal_edge(5,ij)
         edge6 = primal_edge(6,ij)
         le_de1 = le_de(edge1)
         le_de2 = le_de(edge2)
         le_de3 = le_de(edge3)
         le_de4 = le_de(edge4)
         le_de5 = le_de(edge5)
         le_de6 = le_de(edge6)
         sign1 = primal_ne(1,ij)
         sign2 = primal_ne(2,ij)
         sign3 = primal_ne(3,ij)
         sign4 = primal_ne(4,ij)
         sign5 = primal_ne(5,ij)
         sign6 = primal_ne(6,ij)
         !DIR$ SIMD
         DO l = 1, llm
            div_ij=0.
            div_ij = div_ij + sign1*le_de1*grad(l,edge1)
            div_ij = div_ij + sign2*le_de2*grad(l,edge2)
            div_ij = div_ij + sign3*le_de3*grad(l,edge3)
            div_ij = div_ij + sign4*le_de4*grad(l,edge4)
            div_ij = div_ij + sign5*le_de5*grad(l,edge5)
            div_ij = div_ij + sign6*le_de6*grad(l,edge6)
            divu(l,ij) = div_ij / Ai(ij)
         END DO
      CASE DEFAULT
         !DIR$ SIMD
         DO l = 1, llm
            div_ij=0.
            DO iedge = 1, primal_deg(ij)
               edge = primal_edge(iedge,ij)
               div_ij = div_ij + primal_ne(iedge,ij)*le_de(edge)*grad(l,edge)
            END DO
            divu(l,ij) = div_ij / Ai(ij)
         END DO
      END SELECT
   END DO
   !$OMP END DO
   !---------------------------- scalar_laplacian ----------------------------------
   !--------------------------------------------------------------------------