Simplify some code that uses SolutionTransfer.

examples/step-31/step-31.cc

@@ -1943,9 +1943,8 @@ namespace Step31
     // and temperature DoFHandler objects, by attaching them to the old dof
     // handlers. With this at place, we can prepare the triangulation and the
     // data vectors for refinement (in this order).
-    std::vector<TrilinosWrappers::MPI::Vector> x_temperature(2);
-    x_temperature[0]                            = temperature_solution;
-    x_temperature[1]                            = old_temperature_solution;
+    const std::vector<TrilinosWrappers::MPI::Vector> x_temperature = {
+      temperature_solution, old_temperature_solution};
     TrilinosWrappers::MPI::BlockVector x_stokes = stokes_solution;
 
     SolutionTransfer<dim, TrilinosWrappers::MPI::Vector> temperature_trans(
@@ -1971,13 +1970,13 @@ namespace Step31
     triangulation.execute_coarsening_and_refinement();
     setup_dofs();
 
-    std::vector<TrilinosWrappers::MPI::Vector> tmp(2);
-    tmp[0].reinit(temperature_solution);
-    tmp[1].reinit(temperature_solution);
+    std::vector<TrilinosWrappers::MPI::Vector> tmp = {
+      TrilinosWrappers::MPI::Vector(temperature_solution),
+      TrilinosWrappers::MPI::Vector(temperature_solution)};
     temperature_trans.interpolate(x_temperature, tmp);
 
-    temperature_solution     = tmp[0];
-    old_temperature_solution = tmp[1];
+    temperature_solution     = std::move(tmp[0]);
+    old_temperature_solution = std::move(tmp[1]);
 
     // After the solution has been transferred we then enforce the constraints
     // on the transferred solution.

examples/step-32/step-32.cc

@@ -3294,12 +3294,10 @@ namespace Step32
       // remainder of the function further down below is then concerned with
       // setting up the data structures again after mesh refinement and
       // restoring the solution vectors on the new mesh.
-      std::vector<const TrilinosWrappers::MPI::Vector *> x_temperature(2);
-      x_temperature[0] = &temperature_solution;
-      x_temperature[1] = &old_temperature_solution;
-      std::vector<const TrilinosWrappers::MPI::BlockVector *> x_stokes(2);
-      x_stokes[0] = &stokes_solution;
-      x_stokes[1] = &old_stokes_solution;
+      const std::vector<const TrilinosWrappers::MPI::Vector *> x_temperature = {
+        &temperature_solution, &old_temperature_solution};
+      const std::vector<const TrilinosWrappers::MPI::BlockVector *> x_stokes = {
+        &stokes_solution, &old_stokes_solution};
 
       triangulation.prepare_coarsening_and_refinement();
 
@@ -3319,27 +3317,25 @@ namespace Step32
         TrilinosWrappers::MPI::Vector distributed_temp1(temperature_rhs);
         TrilinosWrappers::MPI::Vector distributed_temp2(temperature_rhs);
 
-        std::vector<TrilinosWrappers::MPI::Vector *> tmp(2);
-        tmp[0] = &(distributed_temp1);
-        tmp[1] = &(distributed_temp2);
+        std::vector<TrilinosWrappers::MPI::Vector *> tmp = {&distributed_temp1,
+                                                            &distributed_temp2};
         temperature_trans.interpolate(tmp);
 
         // enforce constraints to make the interpolated solution conforming on
         // the new mesh:
         temperature_constraints.distribute(distributed_temp1);
         temperature_constraints.distribute(distributed_temp2);
 
-        temperature_solution     = distributed_temp1;
-        old_temperature_solution = distributed_temp2;
+        temperature_solution     = std::move(distributed_temp1);
+        old_temperature_solution = std::move(distributed_temp2);
       }
 
       {
         TrilinosWrappers::MPI::BlockVector distributed_stokes(stokes_rhs);
         TrilinosWrappers::MPI::BlockVector old_distributed_stokes(stokes_rhs);
 
-        std::vector<TrilinosWrappers::MPI::BlockVector *> stokes_tmp(2);
-        stokes_tmp[0] = &(distributed_stokes);
-        stokes_tmp[1] = &(old_distributed_stokes);
+        std::vector<TrilinosWrappers::MPI::BlockVector *> stokes_tmp = {
+          &distributed_stokes, &old_distributed_stokes};
 
         stokes_trans.interpolate(stokes_tmp);
 
@@ -3348,8 +3344,8 @@ namespace Step32
         stokes_constraints.distribute(distributed_stokes);
         stokes_constraints.distribute(old_distributed_stokes);
 
-        stokes_solution     = distributed_stokes;
-        old_stokes_solution = old_distributed_stokes;
+        stokes_solution     = std::move(distributed_stokes);
+        old_stokes_solution = std::move(old_distributed_stokes);
       }
     }
   }

examples/step-33/step-33.cc

@@ -2264,11 +2264,7 @@ namespace Step33
     // examples, so we won't comment much on the following code. The last
     // three lines simply re-set the sizes of some other vectors to the now
     // correct size:
-    std::vector<Vector<double>> transfer_in;
-    std::vector<Vector<double>> transfer_out;
-
-    transfer_in.push_back(old_solution);
-    transfer_in.push_back(predictor);
+    const std::vector<Vector<double>> transfer_in = {old_solution, predictor};
 
     triangulation.prepare_coarsening_and_refinement();
 
@@ -2280,26 +2276,17 @@ namespace Step33
     dof_handler.clear();
     dof_handler.distribute_dofs(fe);
 
-    {
-      Vector<double> new_old_solution(1);
-      Vector<double> new_predictor(1);
-
-      transfer_out.push_back(new_old_solution);
-      transfer_out.push_back(new_predictor);
-      transfer_out[0].reinit(dof_handler.n_dofs());
-      transfer_out[1].reinit(dof_handler.n_dofs());
-    }
-
+    std::vector<Vector<double>> transfer_out = {
+      Vector<double>(dof_handler.n_dofs()),
+      Vector<double>(dof_handler.n_dofs())};
     soltrans.interpolate(transfer_in, transfer_out);
 
-    old_solution.reinit(transfer_out[0].size());
-    old_solution = transfer_out[0];
-
-    predictor.reinit(transfer_out[1].size());
-    predictor = transfer_out[1];
+    old_solution = std::move(transfer_out[0]);
+    predictor    = std::move(transfer_out[1]);
 
     current_solution.reinit(dof_handler.n_dofs());
     current_solution = old_solution;
+
     right_hand_side.reinit(dof_handler.n_dofs());
   }
 

include/deal.II/numerics/solution_transfer.h

@@ -91,7 +91,8 @@ DEAL_II_NAMESPACE_OPEN
  * std::vector<Vector<double> > solutions(n_vectors, Vector<double> (n));
  * soltrans.refine_interpolate(solutions_old, solutions);
  * @endcode
- * This is used in several of the tutorial programs, for example step-31.
+ * This is used in several of the tutorial programs, for example step-31
+ * and step-33.
  *
  * <li> If the grid has cells that will be coarsened, then use @p
  * SolutionTransfer as follows: