Пример #1
0
int main(int argc, char* argv[])
{
  // Choose a Butcher's table or define your own.
  ButcherTable bt(butcher_table_type);
  if (bt.is_explicit()) Hermes::Mixins::Loggable::Static::info("Using a %d-stage explicit R-K method.", bt.get_size());
  if (bt.is_diagonally_implicit()) Hermes::Mixins::Loggable::Static::info("Using a %d-stage diagonally implicit R-K method.", bt.get_size());
  if (bt.is_fully_implicit()) Hermes::Mixins::Loggable::Static::info("Using a %d-stage fully implicit R-K method.", bt.get_size());

  // Turn off adaptive time stepping if R-K method is not embedded.
  if (bt.is_embedded() == false && ADAPTIVE_TIME_STEP_ON == true) {
    Hermes::Mixins::Loggable::Static::warn("R-K method not embedded, turning off adaptive time stepping.");
    ADAPTIVE_TIME_STEP_ON = false;
  }

  // Load the mesh.
  MeshSharedPtr mesh(new Mesh), basemesh(new Mesh);
  MeshReaderH2D mloader;
  mloader.load("wall.mesh", basemesh);
  mesh->copy(basemesh);

  // Perform initial mesh refinements.
  for(int i = 0; i < INIT_REF_NUM; i++) mesh->refine_all_elements();
  mesh->refine_towards_boundary(BDY_RIGHT, 2);
  mesh->refine_towards_boundary(BDY_FIRE, INIT_REF_NUM_BDY);

  // Initialize essential boundary conditions (none).
  EssentialBCs<double> bcs;

  // Initialize an H1 space with default shapeset.
  SpaceSharedPtr<double> space(new H1Space<double>(mesh, &bcs, P_INIT));
  int ndof = Space<double>::get_num_dofs(space);
  Hermes::Mixins::Loggable::Static::info("ndof = %d.", ndof);

  // Convert initial condition into a Solution.
  MeshFunctionSharedPtr<double> sln_prev_time(new ConstantSolution<double> (mesh, TEMP_INIT));

  // Initialize the weak formulation.
  double current_time = 0;
  CustomWeakFormHeatRK wf(BDY_FIRE, BDY_AIR, ALPHA_FIRE, ALPHA_AIR,
    RHO, HEATCAP, TEMP_EXT_AIR, TEMP_INIT, &current_time);

  // Initialize the FE problem.
  DiscreteProblem<double> dp(&wf, space);

  // Create a refinement selector.
  H1ProjBasedSelector<double> selector(CAND_LIST);

  // Visualize initial condition.
  char title[100];
  ScalarView sln_view("Initial condition", new WinGeom(0, 0, 1500, 360));
  OrderView ordview("Initial mesh", new WinGeom(0, 410, 1500, 360));
  ScalarView time_error_view("Temporal error", new WinGeom(0, 800, 1500, 360));
  time_error_view.fix_scale_width(40);
  ScalarView space_error_view("Spatial error", new WinGeom(0, 1220, 1500, 360));
  space_error_view.fix_scale_width(40);
  sln_view.show(sln_prev_time);
  ordview.show(space);

  // Graph for time step history.
  SimpleGraph time_step_graph;
  if (ADAPTIVE_TIME_STEP_ON) Hermes::Mixins::Loggable::Static::info("Time step history will be saved to file time_step_history.dat.");

  // Class for projections.
  OGProjection<double> ogProjection;

  // Time stepping loop:
  int ts = 1;
  do 
  {
    Hermes::Mixins::Loggable::Static::info("Begin time step %d.", ts);
    // Periodic global derefinement.
    if (ts > 1 && ts % UNREF_FREQ == 0) 
    {
      Hermes::Mixins::Loggable::Static::info("Global mesh derefinement.");
      switch (UNREF_METHOD) {
      case 1: mesh->copy(basemesh);
        space->set_uniform_order(P_INIT);
        break;
      case 2: space->unrefine_all_mesh_elements();
        space->set_uniform_order(P_INIT);
        break;
      case 3: space->unrefine_all_mesh_elements();
        //space->adjust_element_order(-1, P_INIT);
        space->adjust_element_order(-1, -1, P_INIT, P_INIT);
        break;
      default: throw Hermes::Exceptions::Exception("Wrong global derefinement method.");
      }

      space->assign_dofs();
      ndof = Space<double>::get_num_dofs(space);
    }

    // Spatial adaptivity loop. Note: sln_prev_time must not be 
    // changed during spatial adaptivity. 
    MeshFunctionSharedPtr<double> ref_sln(new Solution<double>());
    MeshFunctionSharedPtr<double> time_error_fn(new Solution<double>(mesh));
    bool done = false; int as = 1;
    double err_est;
    do {
      // Construct globally refined reference mesh and setup reference space.
      Mesh::ReferenceMeshCreator refMeshCreator(mesh);
      MeshSharedPtr ref_mesh = refMeshCreator.create_ref_mesh();

      Space<double>::ReferenceSpaceCreator refSpaceCreator(space, ref_mesh);
      SpaceSharedPtr<double> ref_space = refSpaceCreator.create_ref_space();

      // Initialize Runge-Kutta time stepping on the reference mesh.
      RungeKutta<double> runge_kutta(&wf, ref_space, &bt);

      try
      {
        ogProjection.project_global(ref_space, sln_prev_time, 
          sln_prev_time);
      }
      catch(Exceptions::Exception& e)
      {
        std::cout << e.what() << std::endl;
        Hermes::Mixins::Loggable::Static::error("Projection failed.");

        return -1;
      }

      // Runge-Kutta step on the fine mesh->
      Hermes::Mixins::Loggable::Static::info("Runge-Kutta time step on fine mesh (t = %g s, tau = %g s, stages: %d).", 
        current_time, time_step, bt.get_size());
      bool verbose = true;
      bool jacobian_changed = false;

      try
      {
        runge_kutta.set_time(current_time);
        runge_kutta.set_time_step(time_step);
        runge_kutta.set_max_allowed_iterations(NEWTON_MAX_ITER);
        runge_kutta.set_tolerance(NEWTON_TOL_FINE);
        runge_kutta.rk_time_step_newton(sln_prev_time, ref_sln, bt.is_embedded() ? time_error_fn : NULL);
      }
      catch(Exceptions::Exception& e)
      {
        std::cout << e.what() << std::endl;
        Hermes::Mixins::Loggable::Static::error("Runge-Kutta time step failed");

        return -1;
      }

      /* If ADAPTIVE_TIME_STEP_ON == true, estimate temporal error. 
      If too large or too small, then adjust it and restart the time step. */

      double rel_err_time = 0;
      if (bt.is_embedded() == true) 
      {
        Hermes::Mixins::Loggable::Static::info("Calculating temporal error estimate.");

        // Show temporal error.
        char title[100];
        sprintf(title, "Temporal error est, spatial adaptivity step %d", as);     
        time_error_view.set_title(title);
        //time_error_view.show_mesh(false);
        time_error_view.show(time_error_fn);

        rel_err_time = Global<double>::calc_norm(time_error_fn.get(), HERMES_H1_NORM) 
          / Global<double>::calc_norm(ref_sln.get(), HERMES_H1_NORM) * 100;
        if (ADAPTIVE_TIME_STEP_ON == false) Hermes::Mixins::Loggable::Static::info("rel_err_time: %g%%", rel_err_time);
      }

      if (ADAPTIVE_TIME_STEP_ON) 
      {
        if (rel_err_time > TIME_ERR_TOL_UPPER) 
        {
          Hermes::Mixins::Loggable::Static::info("rel_err_time %g%% is above upper limit %g%%", rel_err_time, TIME_ERR_TOL_UPPER);
          Hermes::Mixins::Loggable::Static::info("Decreasing tau from %g to %g s and restarting time step.", 
            time_step, time_step * TIME_STEP_DEC_RATIO);
          time_step *= TIME_STEP_DEC_RATIO;
          continue;
        }
        else if (rel_err_time < TIME_ERR_TOL_LOWER) 
        {
          Hermes::Mixins::Loggable::Static::info("rel_err_time = %g%% is below lower limit %g%%", rel_err_time, TIME_ERR_TOL_LOWER);
          Hermes::Mixins::Loggable::Static::info("Increasing tau from %g to %g s.", time_step, time_step * TIME_STEP_INC_RATIO);
          time_step *= TIME_STEP_INC_RATIO;
        }
        else 
        {
          Hermes::Mixins::Loggable::Static::info("rel_err_time = %g%% is in acceptable interval (%g%%, %g%%)", 
            rel_err_time, TIME_ERR_TOL_LOWER, TIME_ERR_TOL_UPPER);
        }

        // Add entry to time step history graph.
        time_step_graph.add_values(current_time, time_step);
        time_step_graph.save("time_step_history.dat");
      }

      /* Estimate spatial errors and perform mesh refinement */

      Hermes::Mixins::Loggable::Static::info("Spatial adaptivity step %d.", as);

      // Project the fine mesh solution onto the coarse mesh.
      MeshFunctionSharedPtr<double> sln(new Solution<double>());
      Hermes::Mixins::Loggable::Static::info("Projecting fine mesh solution on coarse mesh for error estimation.");
      ogProjection.project_global(space, ref_sln, sln); 

      // Show spatial error.
      sprintf(title, "Spatial error est, spatial adaptivity step %d", as);  
      MeshFunctionSharedPtr<double> space_error_fn(new DiffFilter<double>(Hermes::vector<MeshFunctionSharedPtr<double> >(ref_sln, sln)));
      space_error_view.set_title(title);
      //space_error_view.show_mesh(false);
      MeshFunctionSharedPtr<double> abs_sef(new AbsFilter(space_error_fn));

      space_error_view.show(abs_sef);

      // Calculate element errors and spatial error estimate.
      Hermes::Mixins::Loggable::Static::info("Calculating spatial error estimate.");
      adaptivity.set_space(space);
      double err_rel_space = errorCalculator.get_total_error_squared() * 100;

      // Report results.
      Hermes::Mixins::Loggable::Static::info("ndof: %d, ref_ndof: %d, err_rel_space: %g%%", 
        Space<double>::get_num_dofs(space), Space<double>::get_num_dofs(ref_space), err_rel_space);

      // If err_est too large, adapt the mesh.
      if (err_rel_space < SPACE_ERR_TOL) done = true;
      else 
      {
        Hermes::Mixins::Loggable::Static::info("Adapting the coarse mesh.");
        done = adaptivity.adapt(&selector);

        if (Space<double>::get_num_dofs(space) >= NDOF_STOP) 
          done = true;
        else
          // Increase the counter of performed adaptivity steps.
          as++;
      }

      // Clean up.
      if(!done)

        
    }
    while (done == false);

    // Visualize the solution and mesh->
    char title[100];
    sprintf(title, "Solution, time %g s", current_time);
    sln_view.set_title(title);
    //sln_view.show_mesh(false);
    sln_view.show(ref_sln);
    sprintf(title, "Mesh, time %g s", current_time);
    ordview.set_title(title);
    ordview.show(space);

    // Copy last reference solution into sln_prev_time
    sln_prev_time->copy(ref_sln);

    // Increase current time and counter of time steps.
    current_time += time_step;
    ts++;
  }
  while (current_time < T_FINAL);

  // Wait for all views to be closed.
  View::wait();
  return 0;
}
Пример #2
0
int main(int argc, char* argv[])
{
  // Choose a Butcher's table or define your own.
  ButcherTable bt(butcher_table_type);
  if (bt.is_explicit()) Hermes::Mixins::Loggable::Static::info("Using a %d-stage explicit R-K method.", bt.get_size());
  if (bt.is_diagonally_implicit()) Hermes::Mixins::Loggable::Static::info("Using a %d-stage diagonally implicit R-K method.", bt.get_size());
  if (bt.is_fully_implicit()) Hermes::Mixins::Loggable::Static::info("Using a %d-stage fully implicit R-K method.", bt.get_size());

  // Load the mesh.
  MeshSharedPtr mesh(new Mesh), basemesh(new Mesh);
  MeshReaderH2D mloader;
  mloader.load("square.mesh", basemesh);
  mesh->copy(basemesh);

  // Initial mesh refinements.
  for(int i = 0; i < INIT_GLOB_REF_NUM; i++) mesh->refine_all_elements();
  mesh->refine_towards_boundary("Top", INIT_REF_NUM_BDY);

  // Initialize boundary conditions.
  CustomEssentialBCNonConst bc_essential(Hermes::vector<std::string>("Bottom", "Right", "Top", "Left"));
  EssentialBCs<double> bcs(&bc_essential);

  // Create an H1 space with default shapeset.
  SpaceSharedPtr<double> space(new H1Space<double>(mesh, &bcs, P_INIT));
  int ndof_coarse = Space<double>::get_num_dofs(space);
  adaptivity.set_space(space);
  Hermes::Mixins::Loggable::Static::info("ndof_coarse = %d.", ndof_coarse);

  // Zero initial solution. This is why we use H_OFFSET.
  MeshFunctionSharedPtr<double> h_time_prev(new ZeroSolution<double>(mesh)), h_time_new(new ZeroSolution<double>(mesh));

  // Initialize the constitutive relations.
  ConstitutiveRelations* constitutive_relations;
  if(constitutive_relations_type == CONSTITUTIVE_GENUCHTEN)
    constitutive_relations = new ConstitutiveRelationsGenuchten(ALPHA, M, N, THETA_S, THETA_R, K_S, STORATIVITY);
  else
    constitutive_relations = new ConstitutiveRelationsGardner(ALPHA, THETA_S, THETA_R, K_S);

  // Initialize the weak formulation.
  CustomWeakFormRichardsRK wf(constitutive_relations);

  // Initialize the FE problem.
  DiscreteProblem<double> dp(&wf, space);

  // Create a refinement selector.
  H1ProjBasedSelector<double> selector(CAND_LIST);

  // Visualize initial condition.
  char title[100];
  ScalarView view("Initial condition", new WinGeom(0, 0, 440, 350));
  OrderView ordview("Initial mesh", new WinGeom(445, 0, 440, 350));
  view.show(h_time_prev);
  ordview.show(space);

  // DOF and CPU convergence graphs initialization.
  SimpleGraph graph_dof, graph_cpu;
  
  // Time measurement.
  Hermes::Mixins::TimeMeasurable cpu_time;
  cpu_time.tick();
  
  // Time stepping loop.
  double current_time = 0; int ts = 1;
  do 
  {
    // Periodic global derefinement.
    if (ts > 1 && ts % UNREF_FREQ == 0) 
    {
      Hermes::Mixins::Loggable::Static::info("Global mesh derefinement.");
      switch (UNREF_METHOD) {
        case 1: mesh->copy(basemesh);
                space->set_uniform_order(P_INIT);
                break;
        case 2: mesh->unrefine_all_elements();
                space->set_uniform_order(P_INIT);
                break;
        case 3: space->unrefine_all_mesh_elements();
                space->adjust_element_order(-1, -1, P_INIT, P_INIT);
                break;
        default: throw Hermes::Exceptions::Exception("Wrong global derefinement method.");
      }

      space->assign_dofs();
      ndof_coarse = Space<double>::get_num_dofs(space);
    }

    // Spatial adaptivity loop. Note: h_time_prev must not be changed 
    // during spatial adaptivity. 
    bool done = false; int as = 1;
    double err_est;
    do {
      Hermes::Mixins::Loggable::Static::info("Time step %d, adaptivity step %d:", ts, as);

      // Construct globally refined reference mesh and setup reference space.
      Mesh::ReferenceMeshCreator refMeshCreator(mesh);
      MeshSharedPtr ref_mesh = refMeshCreator.create_ref_mesh();

      Space<double>::ReferenceSpaceCreator refSpaceCreator(space, ref_mesh);
      SpaceSharedPtr<double> ref_space = refSpaceCreator.create_ref_space();
      int ndof_ref = Space<double>::get_num_dofs(ref_space);

      // Time measurement.
      cpu_time.tick();

      // Initialize Runge-Kutta time stepping.
      RungeKutta<double> runge_kutta(&wf, ref_space, &bt);

      // Perform one Runge-Kutta time step according to the selected Butcher's table.
      Hermes::Mixins::Loggable::Static::info("Runge-Kutta time step (t = %g s, tau = %g s, stages: %d).",
           current_time, time_step, bt.get_size());
      try
      {
        runge_kutta.set_time(current_time);
        runge_kutta.set_time_step(time_step);
        runge_kutta.set_max_allowed_iterations(NEWTON_MAX_ITER);
        runge_kutta.set_tolerance(NEWTON_TOL);
        runge_kutta.rk_time_step_newton(h_time_prev, h_time_new);
      }
      catch(Exceptions::Exception& e)
      {
        e.print_msg();
        throw Hermes::Exceptions::Exception("Runge-Kutta time step failed");
      }

      // Project the fine mesh solution onto the coarse mesh.
      MeshFunctionSharedPtr<double> sln_coarse(new Solution<double>);
      Hermes::Mixins::Loggable::Static::info("Projecting fine mesh solution on coarse mesh for error estimation.");
      OGProjection<double> ogProjection; ogProjection.project_global(space, h_time_new, sln_coarse); 

      // Calculate element errors and total error estimate.
      Hermes::Mixins::Loggable::Static::info("Calculating error estimate.");
      errorCalculator.calculate_errors(sln_coarse, h_time_new, true);
      double err_est_rel_total = errorCalculator.get_total_error_squared() * 100;

      // Report results.
      Hermes::Mixins::Loggable::Static::info("ndof_coarse: %d, ndof_ref: %d, err_est_rel: %g%%", 
           Space<double>::get_num_dofs(space), Space<double>::get_num_dofs(ref_space), err_est_rel_total);

      // Time measurement.
      cpu_time.tick();

      // If err_est too large, adapt the mesh.
      if (err_est_rel_total < ERR_STOP) done = true;
      else 
      {
        Hermes::Mixins::Loggable::Static::info("Adapting the coarse mesh.");
        done = adaptivity.adapt(&selector);

        // Increase the counter of performed adaptivity steps.
        as++;
      }
    }
    while (done == false);

    // Add entry to DOF and CPU convergence graphs.
    graph_dof.add_values(current_time, Space<double>::get_num_dofs(space));
    graph_dof.save("conv_dof_est.dat");
    graph_cpu.add_values(current_time, cpu_time.accumulated());
    graph_cpu.save("conv_cpu_est.dat");

    // Visualize the solution and mesh->
    char title[100];
    sprintf(title, "Solution, time %g", current_time);
    view.set_title(title);
    view.show_mesh(false);
    view.show(h_time_new);
    sprintf(title, "Mesh, time %g", current_time);
    ordview.set_title(title);
    ordview.show(space);

    // Copy last reference solution into h_time_prev.
    h_time_prev->copy(h_time_new);

    // Increase current time and counter of time steps.
    current_time += time_step;
    ts++;
  }
  while (current_time < T_FINAL);

  // Wait for all views to be closed.
  View::wait();
  return 0;
}
Пример #3
0
int main(int argc, char* argv[])
{
  // Initialize refinement selector.
  MySelector selector(hORpSelectionBasedOnDOFs);

  HermesCommonApi.set_integral_param_value(Hermes::showInternalWarnings, false);

  // Time measurement.
  Hermes::Mixins::TimeMeasurable cpu_time;
  cpu_time.tick();

  // Load the mesh.
  MeshSharedPtr mesh(new Mesh);
  MeshReaderH2D mloader;
  mloader.load("domain.mesh", mesh);

  // Error calculation & adaptivity.
  DefaultErrorCalculator<complex, HERMES_H1_NORM> errorCalculator(RelativeErrorToGlobalNorm, 1);
  // Stopping criterion for an adaptivity step.
  AdaptStoppingCriterionSingleElement<complex> stoppingCriterion(THRESHOLD);
  // Adaptivity processor class.
  Adapt<complex> adaptivity(&errorCalculator, &stoppingCriterion);

  // Perform initial mesh refinements.
  for (int i = 0; i < INIT_REF_NUM; i++) mesh->refine_all_elements();

  // Initialize boundary conditions.
  DefaultEssentialBCConst<complex> bc_essential("Source", P_SOURCE);
  EssentialBCs<complex> bcs(&bc_essential);

  // Create an H1 space with default shapeset.
  SpaceSharedPtr<complex> space(new H1Space<complex> (mesh, &bcs, P_INIT));
  int ndof = Space<complex>::get_num_dofs(space);
  //Hermes::Mixins::Loggable::Static::info("ndof = %d", ndof);

  // Initialize the weak formulation.
  CustomWeakFormAcoustics wf("Wall", RHO, SOUND_SPEED, OMEGA);

  // Initialize coarse and reference mesh solution.
  MeshFunctionSharedPtr<complex>  sln(new Solution<complex>), ref_sln(new Solution<complex>);

  // Initialize views.
  ScalarView sview("Acoustic pressure", new WinGeom(600, 0, 600, 350));
  sview.show_contours(.2);
  ScalarView eview("Error", new WinGeom(600, 377, 600, 350));
  sview.show_mesh(false);
  sview.fix_scale_width(50);
  OrderView  oview("Polynomial orders", new WinGeom(1208, 0, 600, 350));
  ScalarView ref_view("Refined elements", new WinGeom(1208, 377, 600, 350));
  ref_view.show_scale(false);
  ref_view.set_min_max_range(0, 2);

  // DOF and CPU convergence graphs initialization.
  SimpleGraph graph_dof, graph_cpu;

  //Hermes::Mixins::Loggable::Static::info("Solving on reference mesh.");
  // Time measurement.
  cpu_time.tick();

  // Perform Newton's iteration.
  Hermes::Hermes2D::NewtonSolver<complex> newton(&wf, space);
  newton.set_verbose_output(false);

  // Adaptivity loop:
  int as = 1;
  adaptivity.set_space(space);
  bool done = false;
  do
  {
    //Hermes::Mixins::Loggable::Static::info("---- Adaptivity step %d:", as);

    // Construct globally refined reference mesh and setup reference space.
    Mesh::ReferenceMeshCreator refMeshCreator(mesh);
    MeshSharedPtr ref_mesh = refMeshCreator.create_ref_mesh();

    Space<complex>::ReferenceSpaceCreator refSpaceCreator(space, ref_mesh);
    SpaceSharedPtr<complex> ref_space = refSpaceCreator.create_ref_space();

    int ndof_ref = Space<complex>::get_num_dofs(ref_space);
    wf.set_verbose_output(false);
    newton.set_space(ref_space);

    // Assemble the reference problem.
    try
    {
      newton.solve();
    }
    catch(Hermes::Exceptions::Exception e)
    {
      e.print_msg();
      throw Hermes::Exceptions::Exception("Newton's iteration failed.");
    };
    // Translate the resulting coefficient vector into the Solution<complex> sln->
    Hermes::Hermes2D::Solution<complex>::vector_to_solution(newton.get_sln_vector(), ref_space, ref_sln);

    // Project the fine mesh solution onto the coarse mesh.
    //Hermes::Mixins::Loggable::Static::info("Projecting reference solution on coarse mesh.");
    OGProjection<complex> ogProjection; ogProjection.project_global(space, ref_sln, sln);

    // Time measurement.
    cpu_time.tick();

    // View the coarse mesh solution and polynomial orders.
    MeshFunctionSharedPtr<double> acoustic_pressure(new RealFilter(sln));
    sview.show(acoustic_pressure);
    oview.show(space);

    // Calculate element errors and total error estimate.
    //Hermes::Mixins::Loggable::Static::info("Calculating error estimate.");
    errorCalculator.calculate_errors(sln, ref_sln);
    double err_est_rel = errorCalculator.get_total_error_squared() * 100;

    eview.show(errorCalculator.get_errorMeshFunction());

    // Report results.
    //Hermes::Mixins::Loggable::Static::info("ndof_coarse: %d, ndof_fine: %d, err_est_rel: %g%%", Space<complex>::get_num_dofs(space), Space<complex>::get_num_dofs(ref_space), err_est_rel);

    // Time measurement.
    cpu_time.tick();

    // Add entry to DOF and CPU convergence graphs.
    graph_dof.add_values(Space<complex>::get_num_dofs(space), err_est_rel);
    graph_dof.save("conv_dof_est.dat");
    graph_cpu.add_values(cpu_time.accumulated(), err_est_rel);
    graph_cpu.save("conv_cpu_est.dat");

    // If err_est too large, adapt the mesh.
    if (err_est_rel < ERR_STOP) done = true;
    else
    {
      //Hermes::Mixins::Loggable::Static::info("Adapting coarse mesh.");
      done = adaptivity.adapt(&selector);
      ref_view.show(adaptivity.get_refinementInfoMeshFunction());
      cpu_time.tick();
      std::cout << "Adaptivity step: " << as << ", running CPU time: " << cpu_time.accumulated_str() << std::endl;
    }

    // Increase counter.
    as++;
  }
  while (done == false);

  //Hermes::Mixins::Loggable::Static::info("Total running time: %g s", cpu_time.accumulated());

  // Show the reference solution - the final result.
  sview.set_title("Fine mesh solution magnitude");

  MeshFunctionSharedPtr<double>  ref_mag(new RealFilter(ref_sln));
  sview.show(ref_mag);

  // Output solution in VTK format.
  Linearizer lin(FileExport);
  bool mode_3D = true;
  lin.save_solution_vtk(ref_mag, "sln.vtk", "Acoustic pressure", mode_3D);
  //Hermes::Mixins::Loggable::Static::info("Solution in VTK format saved to file %s.", "sln.vtk");

  // Wait for all views to be closed.
  View::wait();
  return 0;
}
Пример #4
0
int main(int argc, char* argv[])
{
#ifdef THREAD_TESTING
  HermesCommonApi.set_integral_param_value(numThreads, 8);
#endif
  // Load the mesh.
  MeshSharedPtr mesh(new Mesh);
  Hermes::vector<MeshSharedPtr> meshes;
  meshes.push_back(mesh);
  MeshReaderH2DXML mloader;
  mloader.load("agrosMesh.msh", meshes);

  // Perform initial mesh refinements.
  for (int i = 0; i < INIT_REF_NUM; i++)
    mesh->refine_all_elements();

  // Initialize boundary conditions.
  DefaultEssentialBCConst<complex> bc_essential("4", P_SOURCE);
  EssentialBCs<complex> bcs(&bc_essential);

  // Create an H1 space with default shapeset.
  SpaceSharedPtr<complex> space(new H1Space<complex> (mesh, &bcs, P_INIT));
  adaptivity.set_space(space);

  // Initialize the weak formulation.
  CustomWeakFormAcoustics wf("0", RHO, SOUND_SPEED, OMEGA);

  // Initialize coarse and reference mesh solution.
  MeshFunctionSharedPtr<complex>  sln(new Solution<complex>), ref_sln(new Solution<complex>);

  // Initialize refinement selector.
  H1ProjBasedSelector<complex> selector(CAND_LIST);

  Hermes::Hermes2D::NewtonSolver<complex> newton;
  newton.set_weak_formulation(&wf);

  // 2 Adaptivity steps:
  int as = 1;
  bool done = false;
  do
  {
    // Construct globally refined reference mesh and setup reference space.
    Mesh::ReferenceMeshCreator refMeshCreator(mesh);
    MeshSharedPtr ref_mesh = refMeshCreator.create_ref_mesh();

    Space<complex>::ReferenceSpaceCreator refSpaceCreator(space, ref_mesh);
    SpaceSharedPtr<complex> ref_space = refSpaceCreator.create_ref_space();

    // Perform Newton's iteration.
    try
    {
      newton.set_space(ref_space);
      newton.solve();
    }
    catch(Hermes::Exceptions::Exception& e)
    {
      e.print_msg();
      throw Hermes::Exceptions::Exception("Newton's iteration failed.");
    };

    // Translate the resulting coefficient vector into the Solution<complex> sln->
    Hermes::Hermes2D::Solution<complex>::vector_to_solution(newton.get_sln_vector(), ref_space, ref_sln);

    // Project the fine mesh solution onto the coarse mesh.
    OGProjection<complex> ogProjection; ogProjection.project_global(space, ref_sln, sln);
    
    // Calculate element errors and total error estimate.
    errorCalculator.calculate_errors(sln, ref_sln);
    adaptivity.adapt(&selector);
  }
  while (as++ < 2);
  return 0;
}
Пример #5
0
int main(int argc, char* argv[])
{
  // Load the mesh.
  Mesh mesh;
  MeshReaderH2D mloader;
  if (ALIGN_MESH) 
    mloader.load("oven_load_circle.mesh", &mesh);
  else 
    mloader.load("oven_load_square.mesh", &mesh);

  // Perform initial mesh refinemets.
  for (int i = 0; i < INIT_REF_NUM; i++) mesh.refine_all_elements();

  // Initialize boundary conditions
  DefaultEssentialBCConst<std::complex<double> > bc_essential(BDY_PERFECT_CONDUCTOR, std::complex<double>(0.0, 0.0));

  EssentialBCs<std::complex<double> > bcs(&bc_essential);

  // Create an Hcurl space with default shapeset.
  HcurlSpace<std::complex<double> > space(&mesh, &bcs, P_INIT);
  int ndof = space.get_num_dofs();
  Hermes::Mixins::Loggable::Static::info("ndof = %d", ndof);

  // Initialize the weak formulation.
  CustomWeakForm wf(e_0, mu_0, mu_r, kappa, omega, J, ALIGN_MESH, &mesh, BDY_CURRENT);

  // Initialize coarse and reference mesh solution.
  Solution<std::complex<double> > sln, ref_sln;

  // Initialize refinements selector.
  HcurlProjBasedSelector<std::complex<double> > selector(CAND_LIST, CONV_EXP, H2DRS_DEFAULT_ORDER);

  // Initialize views.
  ScalarView eview("Electric field", new WinGeom(0, 0, 580, 400));
  OrderView  oview("Polynomial orders", new WinGeom(590, 0, 550, 400));
  
  // DOF and CPU convergence graphs initialization.
  SimpleGraph graph_dof, graph_cpu;
  
  // Time measurement.
  Hermes::Mixins::TimeMeasurable cpu_time;
  cpu_time.tick();

  // Adaptivity loop:
  int as = 1; bool done = false;
  do
  {
    Hermes::Mixins::Loggable::Static::info("---- Adaptivity step %d:", as);

    // Construct globally refined reference mesh and setup reference space.
    Mesh::ReferenceMeshCreator refMeshCreator(&mesh);
    Mesh* ref_mesh = refMeshCreator.create_ref_mesh();

    Space<std::complex<double> >::ReferenceSpaceCreator refSpaceCreator(&space, ref_mesh);
    Space<std::complex<double> >* ref_space = refSpaceCreator.create_ref_space();
    int ndof_ref = Space<std::complex<double> >::get_num_dofs(ref_space);

    // Initialize reference problem.
    Hermes::Mixins::Loggable::Static::info("Solving on reference mesh.");
    DiscreteProblem<std::complex<double> > dp(&wf, ref_space);

    // Time measurement.
    cpu_time.tick();

    // Perform Newton's iteration.
    Hermes::Hermes2D::NewtonSolver<std::complex<double> > newton(&dp);
    try
    {
      newton.set_newton_max_iter(NEWTON_MAX_ITER);
      newton.set_newton_tol(NEWTON_TOL);
      newton.solve();
    }
    catch(Hermes::Exceptions::Exception e)
    {
      e.print_msg();
      throw Hermes::Exceptions::Exception("Newton's iteration failed.");
    };
    // Translate the resulting coefficient vector into the Solution<std::complex<double> > sln.
    Hermes::Hermes2D::Solution<std::complex<double> >::vector_to_solution(newton.get_sln_vector(), ref_space, &ref_sln);
  
    // Project the fine mesh solution onto the coarse mesh.
    Hermes::Mixins::Loggable::Static::info("Projecting reference solution on coarse mesh.");
    OGProjection<std::complex<double> > ogProjection; ogProjection.project_global(&space, &ref_sln, &sln); 
   
    // View the coarse mesh solution and polynomial orders.
    RealFilter real(&sln);
    MagFilter<double> magn(&real);
    ValFilter limited_magn(&magn, 0.0, 4e3);
    char title[100];
    sprintf(title, "Electric field, adaptivity step %d", as);
    eview.set_title(title);
    //eview.set_min_max_range(0.0, 4e3);
    eview.show(&limited_magn);
    sprintf(title, "Polynomial orders, adaptivity step %d", as);
    oview.set_title(title);
    oview.show(&space);

    // Calculate element errors and total error estimate.
    Hermes::Mixins::Loggable::Static::info("Calculating error estimate."); 
    Adapt<std::complex<double> >* adaptivity = new Adapt<std::complex<double> >(&space);

    // Set custom error form and calculate error estimate.
    CustomErrorForm cef(kappa);
    adaptivity->set_error_form(0, 0, &cef);
    double err_est_rel = adaptivity->calc_err_est(&sln, &ref_sln) * 100;

    // Report results.
    Hermes::Mixins::Loggable::Static::info("ndof_coarse: %d, ndof_fine: %d, err_est_rel: %g%%", 
      Space<std::complex<double> >::get_num_dofs(&space), 
      Space<std::complex<double> >::get_num_dofs(ref_space), err_est_rel);

    // Time measurement.
    cpu_time.tick();

    // Add entry to DOF and CPU convergence graphs.
    graph_dof.add_values(Space<std::complex<double> >::get_num_dofs(&space), err_est_rel);
    graph_dof.save("conv_dof_est.dat");
    graph_cpu.add_values(cpu_time.accumulated(), err_est_rel);
    graph_cpu.save("conv_cpu_est.dat");

    // If err_est too large, adapt the mesh.
    if (err_est_rel < ERR_STOP) done = true;
    else 
    {
      Hermes::Mixins::Loggable::Static::info("Adapting coarse mesh.");
      done = adaptivity->adapt(&selector, THRESHOLD, STRATEGY, MESH_REGULARITY);
    }
    if (space.get_num_dofs() >= NDOF_STOP) done = true;

    delete adaptivity;
    if(!done)
    {
      delete ref_space->get_mesh();
      delete ref_space;
    }
    
    // Increase counter.
    as++;
  }
  while (done == false);
  
  Hermes::Mixins::Loggable::Static::info("Total running time: %g s", cpu_time.accumulated());

  RealFilter ref_real(&sln);
  MagFilter<double> ref_magn(&ref_real);
  ValFilter ref_limited_magn(&ref_magn, 0.0, 4e3);
  eview.set_title("Fine mesh solution - magnitude");
  eview.show(&ref_limited_magn);

  // Output solution in VTK format.
  Linearizer lin;
  bool mode_3D = true;
  lin.save_solution_vtk(&ref_limited_magn, "sln.vtk", "Magnitude of E", mode_3D);
  Hermes::Mixins::Loggable::Static::info("Solution in VTK format saved to file %s.", "sln.vtk");

  // Wait for all views to be closed.
  View::wait();
  return 0;
}
Пример #6
0
int main(int argc, char* argv[])
{
  // Choose a Butcher's table or define your own.
  ButcherTable bt(butcher_table_type);
  if (bt.is_explicit()) Hermes::Mixins::Loggable::Static::info("Using a %d-stage explicit R-K method.", bt.get_size());
  if (bt.is_diagonally_implicit()) Hermes::Mixins::Loggable::Static::info("Using a %d-stage diagonally implicit R-K method.", bt.get_size());
  if (bt.is_fully_implicit()) Hermes::Mixins::Loggable::Static::info("Using a %d-stage fully implicit R-K method.", bt.get_size());

  // Turn off adaptive time stepping if R-K method is not embedded.
  if (bt.is_embedded() == false && ADAPTIVE_TIME_STEP_ON == true) {
    Hermes::Mixins::Loggable::Static::warn("R-K method not embedded, turning off adaptive time stepping.");
    ADAPTIVE_TIME_STEP_ON = false;
  }

  // Load the mesh.
  MeshSharedPtr mesh(new Mesh), basemesh(new Mesh);
  MeshReaderH2D mloader;
  mloader.load("square.mesh", basemesh);
  mesh->copy(basemesh);

  // Initial mesh refinements.
  for(int i = 0; i < INIT_REF_NUM; i++) mesh->refine_all_elements();

  // Convert initial condition into a Solution<complex>.
  MeshFunctionSharedPtr<complex> psi_time_prev(new CustomInitialCondition(mesh));

  // Initialize the weak formulation.
  double current_time = 0;

  // Initialize weak formulation.
  CustomWeakFormGPRK wf(h, m, g, omega);

  // Initialize boundary conditions.
  DefaultEssentialBCConst<complex> bc_essential("Bdy", 0.0);
  EssentialBCs<complex> bcs(&bc_essential);

  // Create an H1 space with default shapeset.
  SpaceSharedPtr<complex> space(new H1Space<complex> (mesh, &bcs, P_INIT));
  int ndof = space->get_num_dofs();
  Hermes::Mixins::Loggable::Static::info("ndof = %d", ndof);

  // Initialize the FE problem.
  DiscreteProblem<complex> dp(&wf, space);

  // Create a refinement selector.
  H1ProjBasedSelector<complex> selector(CAND_LIST);

  // Visualize initial condition.
  char title[100];

  ScalarView sview_real("Initial condition - real part", new WinGeom(0, 0, 600, 500));
  ScalarView sview_imag("Initial condition - imaginary part", new WinGeom(610, 0, 600, 500));

  sview_real.show_mesh(false);
  sview_imag.show_mesh(false);
  sview_real.fix_scale_width(50);
  sview_imag.fix_scale_width(50);
  OrderView ord_view("Initial mesh", new WinGeom(445, 0, 440, 350));
  ord_view.fix_scale_width(50);
  ScalarView time_error_view("Temporal error", new WinGeom(0, 400, 440, 350));
  time_error_view.fix_scale_width(50);
  time_error_view.fix_scale_width(60);
  ScalarView space_error_view("Spatial error", new WinGeom(445, 400, 440, 350));
  space_error_view.fix_scale_width(50);
  MeshFunctionSharedPtr<double> real(new RealFilter(psi_time_prev));

  MeshFunctionSharedPtr<double> imag(new ImagFilter(psi_time_prev));

  sview_real.show(real);
  sview_imag.show(imag);
  ord_view.show(space);

  // Graph for time step history.
  SimpleGraph time_step_graph;
  if (ADAPTIVE_TIME_STEP_ON) Hermes::Mixins::Loggable::Static::info("Time step history will be saved to file time_step_history.dat.");

  // Time stepping:
  int num_time_steps = (int)(T_FINAL/time_step + 0.5);
  for(int ts = 1; ts <= num_time_steps; ts++)
    // Time stepping loop.
      double current_time = 0.0; int ts = 1;
  do 
  {
    Hermes::Mixins::Loggable::Static::info("Begin time step %d.", ts);
    // Periodic global derefinement.
    if (ts > 1 && ts % UNREF_FREQ == 0) 
    {
      Hermes::Mixins::Loggable::Static::info("Global mesh derefinement.");
      switch (UNREF_METHOD) {
      case 1: mesh->copy(basemesh);
        space->set_uniform_order(P_INIT);
        break;
      case 2: space->unrefine_all_mesh_elements();
        space->set_uniform_order(P_INIT);
        break;
      case 3: space->unrefine_all_mesh_elements();
        space->adjust_element_order(-1, -1, P_INIT, P_INIT);
        break;
      default: throw Hermes::Exceptions::Exception("Wrong global derefinement method.");
      }

      ndof = Space<complex>::get_num_dofs(space);
    }
    Hermes::Mixins::Loggable::Static::info("ndof: %d", ndof);

    // Spatial adaptivity loop. Note: psi_time_prev must not be 
    // changed during spatial adaptivity. 
    MeshFunctionSharedPtr<complex> ref_sln(new Solution<complex>());
    MeshFunctionSharedPtr<complex> time_error_fn(new Solution<complex>);
    bool done = false;
    int as = 1;
    double err_est;
    do {
      // Construct globally refined reference mesh and setup reference space.
      Mesh::ReferenceMeshCreator refMeshCreator(mesh);
      MeshSharedPtr ref_mesh = refMeshCreator.create_ref_mesh();

      Space<complex>::ReferenceSpaceCreator refSpaceCreator(space, ref_mesh);
      SpaceSharedPtr<complex> ref_space = refSpaceCreator.create_ref_space();

      // Initialize discrete problem on reference mesh.
      DiscreteProblem<complex>* ref_dp = new DiscreteProblem<complex>(&wf, ref_space);

      RungeKutta<complex> runge_kutta(&wf, ref_space, &bt);

      // Runge-Kutta step on the fine mesh->
      Hermes::Mixins::Loggable::Static::info("Runge-Kutta time step on fine mesh (t = %g s, time step = %g s, stages: %d).", 
        current_time, time_step, bt.get_size());
      bool verbose = true;

      try
      {
        runge_kutta.set_time(current_time);
        runge_kutta.set_time_step(time_step);
        runge_kutta.set_max_allowed_iterations(NEWTON_MAX_ITER);
        runge_kutta.set_tolerance(NEWTON_TOL_FINE);
        runge_kutta.rk_time_step_newton(psi_time_prev, ref_sln, time_error_fn);
      }
      catch(Exceptions::Exception& e)
      {
        e.print_msg();
        throw Hermes::Exceptions::Exception("Runge-Kutta time step failed");
      }

      /* If ADAPTIVE_TIME_STEP_ON == true, estimate temporal error. 
      If too large or too small, then adjust it and restart the time step. */

      double rel_err_time = 0;
      if (bt.is_embedded() == true) {
        Hermes::Mixins::Loggable::Static::info("Calculating temporal error estimate.");

        // Show temporal error.
        char title[100];
        sprintf(title, "Temporal error est, spatial adaptivity step %d", as);     
        time_error_view.set_title(title);
        time_error_view.show_mesh(false);
        MeshFunctionSharedPtr<double> abs_time(new RealFilter(time_error_fn));

        MeshFunctionSharedPtr<double> abs_tef(new AbsFilter(abs_time));

        time_error_view.show(abs_tef);

        rel_err_time = Global<complex>::calc_norm(time_error_fn.get(), HERMES_H1_NORM) / 
          Global<complex>::calc_norm(ref_sln.get(), HERMES_H1_NORM) * 100;
        if (ADAPTIVE_TIME_STEP_ON == false) Hermes::Mixins::Loggable::Static::info("rel_err_time: %g%%", rel_err_time);
      }

      if (ADAPTIVE_TIME_STEP_ON) {
        if (rel_err_time > TIME_ERR_TOL_UPPER) {
          Hermes::Mixins::Loggable::Static::info("rel_err_time %g%% is above upper limit %g%%", rel_err_time, TIME_ERR_TOL_UPPER);
          Hermes::Mixins::Loggable::Static::info("Decreasing time step from %g to %g s and restarting time step.", 
            time_step, time_step * TIME_STEP_DEC_RATIO);
          time_step *= TIME_STEP_DEC_RATIO;

          delete ref_dp;
          continue;
        }
        else if (rel_err_time < TIME_ERR_TOL_LOWER) {
          Hermes::Mixins::Loggable::Static::info("rel_err_time = %g%% is below lower limit %g%%", rel_err_time, TIME_ERR_TOL_LOWER);
          Hermes::Mixins::Loggable::Static::info("Increasing time step from %g to %g s.", time_step, time_step * TIME_STEP_INC_RATIO);
          time_step *= TIME_STEP_INC_RATIO;

          delete ref_dp;
          continue;
        }
        else {
          Hermes::Mixins::Loggable::Static::info("rel_err_time = %g%% is in acceptable interval (%g%%, %g%%)", 
            rel_err_time, TIME_ERR_TOL_LOWER, TIME_ERR_TOL_UPPER);
        }

        // Add entry to time step history graph.
        time_step_graph.add_values(current_time, time_step);
        time_step_graph.save("time_step_history.dat");
      }

      /* Estimate spatial errors and perform mesh refinement */

      Hermes::Mixins::Loggable::Static::info("Spatial adaptivity step %d.", as);

      // Project the fine mesh solution onto the coarse mesh.
      MeshFunctionSharedPtr<complex> sln(new Solution<complex>);
      Hermes::Mixins::Loggable::Static::info("Projecting fine mesh solution on coarse mesh for error estimation.");
      OGProjection<complex> ogProjection; ogProjection.project_global(space, ref_sln, sln); 

      // Show spatial error.
      sprintf(title, "Spatial error est, spatial adaptivity step %d", as);  
      MeshFunctionSharedPtr<complex> space_error_fn(new DiffFilter<complex>(Hermes::vector<MeshFunctionSharedPtr<complex> >(ref_sln, sln)));

      space_error_view.set_title(title);
      space_error_view.show_mesh(false);

      MeshFunctionSharedPtr<double> abs_space(new RealFilter(space_error_fn));
      MeshFunctionSharedPtr<double> abs_sef(new AbsFilter(abs_space));

      space_error_view.show(abs_sef);

      // Calculate element errors and spatial error estimate.
      Hermes::Mixins::Loggable::Static::info("Calculating spatial error estimate.");
      Adapt<complex> adaptivity(space);
      double err_rel_space = errorCalculator.get_total_error_squared() * 100;

      // Report results.
      Hermes::Mixins::Loggable::Static::info("ndof: %d, ref_ndof: %d, err_rel_space: %g%%", 
        Space<complex>::get_num_dofs(space), Space<complex>::get_num_dofs(ref_space), err_rel_space);

      // If err_est too large, adapt the mesh.
      if (err_rel_space < SPACE_ERR_TOL) done = true;
      else 
      {
        Hermes::Mixins::Loggable::Static::info("Adapting the coarse mesh.");
        done = adaptivity.adapt(&selector);

        // Increase the counter of performed adaptivity steps.
        as++;
      }

      // Clean up.
      
      delete ref_dp;
    }
    while (done == false);

    // Visualize the solution and mesh->
    char title[100];
    sprintf(title, "Solution - real part, Time %3.2f s", current_time);
    sview_real.set_title(title);
    sprintf(title, "Solution - imaginary part, Time %3.2f s", current_time);
    sview_imag.set_title(title);
    MeshFunctionSharedPtr<double> real(new RealFilter(ref_sln));
    MeshFunctionSharedPtr<double> imag(new ImagFilter(ref_sln));
    sview_real.show(real);
    sview_imag.show(imag);
    sprintf(title, "Mesh, time %g s", current_time);
    ord_view.set_title(title);
    ord_view.show(space);

    // Copy last reference solution into psi_time_prev.
    psi_time_prev->copy(ref_sln);

    // Increase current time and counter of time steps.
    current_time += time_step;
    ts++;
  }
  while (current_time < T_FINAL);

  // Wait for all views to be closed.
  View::wait();
  return 0;
}
Пример #7
0
int main(int argc, char* argv[])
{
  // Load the mesh.
  MeshSharedPtr mesh(new Mesh);
  MeshReaderH2D mloader;
  mloader.load("square_quad.mesh", mesh);
  // mloader.load("square_tri.mesh", mesh);

  // Perform initial mesh refinement.
  for (int i = 0; i < INIT_REF_NUM; i++) mesh->refine_all_elements();
  mesh->refine_towards_boundary("Layer", INIT_REF_NUM_BDY);

  // Initialize the weak formulation.
  WeakFormSharedPtr<double> wf(new WeakFormLinearAdvectionDiffusion(STABILIZATION_ON, SHOCK_CAPTURING_ON, B1, B2, EPSILON));

  // Initialize boundary conditions
  DefaultEssentialBCConst<double> bc_rest("Rest", 1.0);
  EssentialBCNonConst bc_layer("Layer");

  EssentialBCs<double> bcs({ &bc_rest, &bc_layer });

  // Create an H1 space with default shapeset.
  SpaceSharedPtr<double> space(new H1Space<double>(mesh, &bcs, P_INIT));

  WinGeom* sln_win_geom = new WinGeom(0, 0, 440, 350);
  WinGeom* mesh_win_geom = new WinGeom(450, 0, 400, 350);

  // Initialize coarse and reference mesh solution.
  MeshFunctionSharedPtr<double> sln(new Solution<double>), ref_sln(new Solution<double>);

  // Initialize refinement selector.
  H1ProjBasedSelector<double> selector(CAND_LIST);

  // Initialize views.
  ScalarView sview("Solution", new WinGeom(0, 0, 440, 350));
  sview.fix_scale_width(50);
  sview.show_mesh(false);
  OrderView  oview("Polynomial orders", new WinGeom(450, 0, 400, 350));

  // DOF and CPU convergence graphs initialization.
  SimpleGraph graph_dof, graph_cpu;

  // Time measurement.
  Hermes::Mixins::TimeMeasurable cpu_time;
  cpu_time.tick();

  // Adaptivity loop:
  int as = 1;
  bool done = false;
  do
  {
    Hermes::Mixins::Loggable::Static::info("---- Adaptivity step %d:", as);

    // Construct globally refined reference mesh and setup reference space.
    Mesh::ReferenceMeshCreator refMeshCreator(mesh);
    MeshSharedPtr ref_mesh = refMeshCreator.create_ref_mesh();

    Space<double>::ReferenceSpaceCreator refSpaceCreator(space, ref_mesh);
    SpaceSharedPtr<double> ref_space = refSpaceCreator.create_ref_space();

    // Assemble the reference problem.
    Hermes::Mixins::Loggable::Static::info("Solving on reference mesh.");
    LinearSolver<double> solver(wf, ref_space);

    // Time measurement.
    cpu_time.tick();

    // Solve the linear system of the reference problem.
    // If successful, obtain the solution.
    solver.solve();
    Solution<double>::vector_to_solution(solver.get_sln_vector(), ref_space, ref_sln);

    // Project the fine mesh solution onto the coarse mesh.
    Hermes::Mixins::Loggable::Static::info("Projecting reference solution on coarse mesh.");
    OGProjection<double>::project_global(space, ref_sln, sln);

    // Time measurement.
    cpu_time.tick();

    // View the coarse mesh solution and polynomial orders.
    sview.show(sln);
    oview.show(space);

    // Skip visualization time.
    cpu_time.tick(Hermes::Mixins::TimeMeasurable::HERMES_SKIP);

    // Calculate element errors and total error estimate.
    Hermes::Mixins::Loggable::Static::info("Calculating error estimate.");
    adaptivity.set_space(space);
    errorCalculator.calculate_errors(sln, ref_sln);
    double err_est_rel = errorCalculator.get_total_error_squared() * 100;

    // Report results.
    Hermes::Mixins::Loggable::Static::info("ndof_coarse: %d, ndof_fine: %d, err_est_rel: %g%%",
      Space<double>::get_num_dofs(space), Space<double>::get_num_dofs(ref_space), err_est_rel);

    // Time measurement.
    cpu_time.tick();

    // Add entry to DOF and CPU convergence graphs.
    graph_dof.add_values(Space<double>::get_num_dofs(space), err_est_rel);
    graph_dof.save("conv_dof_est.dat");
    graph_cpu.add_values(cpu_time.accumulated(), err_est_rel);
    graph_cpu.save("conv_cpu_est.dat");

    // If err_est too large, adapt the mesh.
    if (err_est_rel < ERR_STOP) done = true;
    else
    {
      Hermes::Mixins::Loggable::Static::info("Adapting coarse mesh.");
      done = adaptivity.adapt(&selector);

      // Increase the counter of performed adaptivity steps.
      if (done == false)  as++;
    }
  } while (done == false);

  Hermes::Mixins::Loggable::Static::info("Total running time: %g s", cpu_time.accumulated());

  // Show the reference solution - the final result.
  sview.set_title("Fine mesh solution");
  sview.show_mesh(false);
  sview.show(ref_sln);

  // Wait for all views to be closed.
  View::wait();
  return 0;
}