Use the new CellSimilarity capability of FEValues in order to speed up assembly.

git-svn-id: https://svn.dealii.org/trunk@18468 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/examples/step-32/step-32.cc b/deal.II/examples/step-32/step-32.cc
index 35adcfff592009c115fe56da9c10c36553ea018d..79fc28af5545485073ba88c7325d055d3ef3cc90 100644 (file)
--- a/deal.II/examples/step-32/step-32.cc
+++ b/deal.II/examples/step-32/step-32.cc
@@ -792,24 +792,30 @@ BoussinesqFlowProblem<dim>::assemble_stokes_preconditioner ()
        Utilities::Trilinos::get_this_mpi_process(trilinos_communicator))
       {
        stokes_fe_values.reinit (cell);
-       local_matrix = 0;
 
-       for (unsigned int q=0; q<n_q_points; ++q)
+                                  // only need to recalculate local matrix
+                                  // if FEValues data has changed.
+       if (stokes_fe_values.get_cell_similarity() != CellSimilarity::translation)
          {
-           for (unsigned int k=0; k<dofs_per_cell; ++k)
+           local_matrix = 0;
+
+           for (unsigned int q=0; q<n_q_points; ++q)
              {
-               phi_grad_u[k] = stokes_fe_values[velocities].gradient(k,q);
-               phi_p[k]      = stokes_fe_values[pressure].value (k, q);
-             }
+               for (unsigned int k=0; k<dofs_per_cell; ++k)
+                 {
+                   phi_grad_u[k] = stokes_fe_values[velocities].gradient(k,q);
+                   phi_p[k]      = stokes_fe_values[pressure].value (k, q);
+                 }
 
-           for (unsigned int i=0; i<dofs_per_cell; ++i)
-             for (unsigned int j=0; j<dofs_per_cell; ++j)
-               local_matrix(i,j) += (EquationData::eta *
-                                     scalar_product (phi_grad_u[i], phi_grad_u[j])
-                                     +
-                                     (1./EquationData::eta) *
-                                     phi_p[i] * phi_p[j])
-                                    * stokes_fe_values.JxW(q);
+               for (unsigned int i=0; i<dofs_per_cell; ++i)
+                 for (unsigned int j=0; j<dofs_per_cell; ++j)
+                   local_matrix(i,j) += (EquationData::eta *
+                                         scalar_product (phi_grad_u[i], phi_grad_u[j])
+                                         +
+                                         (1./EquationData::eta) *
+                                         phi_p[i] * phi_p[j])
+                                        * stokes_fe_values.JxW(q);
+             }
          }
 
        cell->get_dof_indices (local_dof_indices);
@@ -926,7 +932,8 @@ void BoussinesqFlowProblem<dim>::assemble_stokes_system ()
        stokes_fe_values.reinit (cell);
        temperature_fe_values.reinit (temperature_cell);
        
-       local_matrix = 0;
+       if (stokes_fe_values.get_cell_similarity() != CellSimilarity::translation)
+         local_matrix = 0;
        local_rhs = 0;
   
        temperature_fe_values.get_function_values (old_temperature_solution, 
@@ -939,7 +946,8 @@ void BoussinesqFlowProblem<dim>::assemble_stokes_system ()
            for (unsigned int k=0; k<dofs_per_cell; ++k)
              {
                phi_u[k] = stokes_fe_values[velocities].value (k,q);
-               if (rebuild_stokes_matrix)
+               if (rebuild_stokes_matrix && 
+                   stokes_fe_values.get_cell_similarity() != CellSimilarity::translation)
                  {
                    grads_phi_u[k] = stokes_fe_values[velocities].symmetric_gradient(k,q);
                    div_phi_u[k]   = stokes_fe_values[velocities].divergence (k, q);
@@ -947,14 +955,15 @@ void BoussinesqFlowProblem<dim>::assemble_stokes_system ()
                  }
              }
   
-           if (rebuild_stokes_matrix)
+           if (rebuild_stokes_matrix &&
+               stokes_fe_values.get_cell_similarity() != CellSimilarity::translation)
              for (unsigned int i=0; i<dofs_per_cell; ++i)
                for (unsigned int j=0; j<dofs_per_cell; ++j)
                  local_matrix(i,j) += (EquationData::eta * 2 *
                                        grads_phi_u[i] * grads_phi_u[j]
                                        - div_phi_u[i] * phi_p[j]
                                        - phi_p[i] * div_phi_u[j])
-                                     * stokes_fe_values.JxW(q);
+                                      * stokes_fe_values.JxW(q);
 
            const Point<dim> gravity = ( (dim == 2) ? (Point<dim> (0,1)) : 
                                         (Point<dim> (0,0,1)) );
@@ -968,12 +977,14 @@ void BoussinesqFlowProblem<dim>::assemble_stokes_system ()
   
        if (rebuild_stokes_matrix == true)
          stokes_constraints.distribute_local_to_global (local_matrix,
+                                                        local_rhs,
                                                         local_dof_indices,
-                                                        stokes_matrix);
-  
-       stokes_constraints.distribute_local_to_global (local_rhs,
-                                                      local_dof_indices,
-                                                      stokes_rhs);
+                                                        stokes_matrix,
+                                                        stokes_rhs);
+       else
+         stokes_constraints.distribute_local_to_global (local_rhs,
+                                                        local_dof_indices,
+                                                        stokes_rhs);
       }
 
   stokes_matrix.compress();
@@ -1024,31 +1035,34 @@ void BoussinesqFlowProblem<dim>::assemble_temperature_matrix ()
     if (cell->subdomain_id() == 
        Utilities::Trilinos::get_this_mpi_process(trilinos_communicator) )
       {
-       local_mass_matrix = 0;
-       local_stiffness_matrix = 0;
-  
        temperature_fe_values.reinit (cell);
        
-       for (unsigned int q=0; q<n_q_points; ++q)
+       if (temperature_fe_values.get_cell_similarity() != CellSimilarity::translation)
          {
-           for (unsigned int k=0; k<dofs_per_cell; ++k)
+           local_mass_matrix = 0;
+           local_stiffness_matrix = 0;
+  
+           for (unsigned int q=0; q<n_q_points; ++q)
              {
-               grad_phi_T[k] = temperature_fe_values.shape_grad (k,q);
-               phi_T[k]      = temperature_fe_values.shape_value (k, q);
+               for (unsigned int k=0; k<dofs_per_cell; ++k)
+                 {
+                   grad_phi_T[k] = temperature_fe_values.shape_grad (k,q);
+                   phi_T[k]      = temperature_fe_values.shape_value (k, q);
+                 }
+
+               for (unsigned int i=0; i<dofs_per_cell; ++i)
+                 for (unsigned int j=0; j<dofs_per_cell; ++j)
+                   {
+                     local_mass_matrix(i,j)
+                       += (phi_T[i] * phi_T[j]
+                           *
+                           temperature_fe_values.JxW(q));
+                     local_stiffness_matrix(i,j)
+                       += (EquationData::kappa * grad_phi_T[i] * grad_phi_T[j]
+                           *
+                           temperature_fe_values.JxW(q));
+                   }
              }
-           
-           for (unsigned int i=0; i<dofs_per_cell; ++i)
-             for (unsigned int j=0; j<dofs_per_cell; ++j)
-               {
-                 local_mass_matrix(i,j)
-                   += (phi_T[i] * phi_T[j]
-                       *
-                       temperature_fe_values.JxW(q));
-                 local_stiffness_matrix(i,j)
-                   += (EquationData::kappa * grad_phi_T[i] * grad_phi_T[j]
-                       *
-                       temperature_fe_values.JxW(q));
-               }
          }
        
        cell->get_dof_indices (local_dof_indices);