Clean up the headers in step-6.

diff --git a/examples/step-6/step-6.cc b/examples/step-6/step-6.cc
index 186c3f48829aa850e4dbe00a7ab0c7a959271fba..ab7d72f5acad14e5427b9b8e1b8f1beba09b8782 100644 (file)
--- a/examples/step-6/step-6.cc
+++ b/examples/step-6/step-6.cc
@@ -23,29 +23,27 @@
 // The first few files have already been covered in previous examples and will
 // thus not be further commented on.
 #include <deal.II/base/quadrature_lib.h>
-#include <deal.II/base/function.h>
-#include <deal.II/base/logstream.h>
-#include <deal.II/lac/vector.h>
-#include <deal.II/lac/full_matrix.h>
-#include <deal.II/lac/sparse_matrix.h>
-#include <deal.II/lac/dynamic_sparsity_pattern.h>
-#include <deal.II/lac/solver_cg.h>
-#include <deal.II/lac/precondition.h>
-#include <deal.II/grid/tria.h>
+#include <deal.II/base/function_lib.h>
+
 #include <deal.II/dofs/dof_handler.h>
-#include <deal.II/grid/grid_generator.h>
-#include <deal.II/grid/tria_accessor.h>
-#include <deal.II/grid/tria_iterator.h>
-#include <deal.II/grid/manifold_lib.h>
-#include <deal.II/dofs/dof_accessor.h>
 #include <deal.II/dofs/dof_tools.h>
+
 #include <deal.II/fe/fe_values.h>
-#include <deal.II/numerics/vector_tools.h>
-#include <deal.II/numerics/matrix_tools.h>
+
+#include <deal.II/grid/tria.h>
+#include <deal.II/grid/grid_generator.h>
+
+#include <deal.II/lac/dynamic_sparsity_pattern.h>
+#include <deal.II/lac/full_matrix.h>
+#include <deal.II/lac/precondition.h>
+#include <deal.II/lac/solver_cg.h>
+#include <deal.II/lac/sparse_matrix.h>
+#include <deal.II/lac/vector.h>
+
 #include <deal.II/numerics/data_out.h>
+#include <deal.II/numerics/vector_tools.h>
 
 #include <fstream>
-#include <iostream>
 
 // From the following include file we will import the declaration of
 // H1-conforming finite element shape functions. This family of finite