Update deprecated deal.II function `extract_boundary_dofs()`

diff --git a/coupled_laplace_problem/coupled_laplace_problem.cc b/coupled_laplace_problem/coupled_laplace_problem.cc
index e295a18b27ee6fbb2f4a5936131575d8403a5b6b..1330bec9653a47e4f138b8e48500fc41332d624b 100644 (file)
--- a/coupled_laplace_problem/coupled_laplace_problem.cc
+++ b/coupled_laplace_problem/coupled_laplace_problem.cc
@@ -177,10 +177,9 @@ Adapter<dim, ParameterClass>::initialize(
 
   // The `ComponentMask()` might be important in case we deal with vector valued
   // problems, because vector valued problems have a DoF for each component.
-  DoFTools::extract_boundary_dofs(dof_handler,
-                                  ComponentMask(),
-                                  coupling_dofs,
-                                  couplingBoundary);
+  coupling_dofs = DoFTools::extract_boundary_dofs(dof_handler,
+                                                  ComponentMask(),
+                                                  couplingBoundary);
 
   // The coupling DoFs are used to set up the `boundary_data` map. At the end,
   // we associate here each DoF with a respective boundary value.