From 623155e10863954e32ea6546745170b062491c50 Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Wed, 5 Apr 2017 10:38:11 -0600
Subject: [PATCH] Implement
 FE::convert_generalized_support_point_values_to_nodal_values() for FE_Q,
 FE_DGQ, FE_DGQArbitraryNodes.

---
 doc/news/changes/minor/20170405Bangerth |  6 ++++
 include/deal.II/fe/fe_dgq.h             | 24 +++++++++++++
 include/deal.II/fe/fe_q.h               | 14 +++++++-
 include/deal.II/fe/fe_q_base.h          |  2 +-
 source/fe/fe_dgq.cc                     | 48 +++++++++++++++++++++++++
 source/fe/fe_q.cc                       | 26 +++++++++++++-
 6 files changed, 117 insertions(+), 3 deletions(-)
 create mode 100644 doc/news/changes/minor/20170405Bangerth

diff --git a/doc/news/changes/minor/20170405Bangerth b/doc/news/changes/minor/20170405Bangerth
new file mode 100644
index 0000000000..d9c9c347fd
--- /dev/null
+++ b/doc/news/changes/minor/20170405Bangerth
@@ -0,0 +1,6 @@
+New: The classes FE_Q, FE_DGQ, and FE_DGQArbitraryNodes now implement
+the
+FiniteElement::convert_generalized_support_point_values_to_nodal_values()
+interface.
+<br>
+(Wolfgang Bangerth, 2017/04/05)
diff --git a/include/deal.II/fe/fe_dgq.h b/include/deal.II/fe/fe_dgq.h
index 1c04563d41..693cc52bca 100644
--- a/include/deal.II/fe/fe_dgq.h
+++ b/include/deal.II/fe/fe_dgq.h
@@ -300,6 +300,18 @@ public:
   virtual std::pair<Table<2,bool>, std::vector<unsigned int> >
   get_constant_modes () const;
 
+  /**
+   * Implementation of the corresponding function in the FiniteElement
+   * class.  Since the current element is interpolatory, the nodal
+   * values are exactly the support point values. Furthermore, since
+   * the current element is scalar, the support point values need to
+   * be vectors of length 1.
+   */
+  virtual
+  void
+  convert_generalized_support_point_values_to_nodal_values (const std::vector<Vector<double> > &support_point_values,
+                                                            std::vector<double>                &nodal_values) const;
+
   /**
    * Determine an estimate for the memory consumption (in bytes) of this
    * object.
@@ -409,6 +421,18 @@ public:
    */
   virtual std::string get_name () const;
 
+  /**
+   * Implementation of the corresponding function in the FiniteElement
+   * class.  Since the current element is interpolatory, the nodal
+   * values are exactly the support point values. Furthermore, since
+   * the current element is scalar, the support point values need to
+   * be vectors of length 1.
+   */
+  virtual
+  void
+  convert_generalized_support_point_values_to_nodal_values (const std::vector<Vector<double> > &support_point_values,
+                                                            std::vector<double>                &nodal_values) const;
+
 protected:
   /**
    * @p clone function instead of a copy constructor.
diff --git a/include/deal.II/fe/fe_q.h b/include/deal.II/fe/fe_q.h
index a19aa9bf4e..7c08e61e45 100644
--- a/include/deal.II/fe/fe_q.h
+++ b/include/deal.II/fe/fe_q.h
@@ -1,6 +1,6 @@
 // ---------------------------------------------------------------------
 //
-// Copyright (C) 2000 - 2016 by the deal.II authors
+// Copyright (C) 2000 - 2017 by the deal.II authors
 //
 // This file is part of the deal.II library.
 //
@@ -586,6 +586,18 @@ public:
    */
   virtual std::string get_name () const;
 
+  /**
+   * Implementation of the corresponding function in the FiniteElement
+   * class.  Since the current element is interpolatory, the nodal
+   * values are exactly the support point values. Furthermore, since
+   * the current element is scalar, the support point values need to
+   * be vectors of length 1.
+   */
+  virtual
+  void
+  convert_generalized_support_point_values_to_nodal_values (const std::vector<Vector<double> > &support_point_values,
+                                                            std::vector<double>                &nodal_values) const;
+
 protected:
 
   /**
diff --git a/include/deal.II/fe/fe_q_base.h b/include/deal.II/fe/fe_q_base.h
index 2a39e81e90..4b9e35e82e 100644
--- a/include/deal.II/fe/fe_q_base.h
+++ b/include/deal.II/fe/fe_q_base.h
@@ -1,6 +1,6 @@
 // ---------------------------------------------------------------------
 //
-// Copyright (C) 2000 - 2016 by the deal.II authors
+// Copyright (C) 2000 - 2017 by the deal.II authors
 //
 // This file is part of the deal.II library.
 //
diff --git a/source/fe/fe_dgq.cc b/source/fe/fe_dgq.cc
index af344ba3fb..bc9159982d 100644
--- a/source/fe/fe_dgq.cc
+++ b/source/fe/fe_dgq.cc
@@ -16,6 +16,7 @@
 
 #include <deal.II/base/quadrature.h>
 #include <deal.II/base/quadrature_lib.h>
+#include <deal.II/lac/vector.h>
 #include <deal.II/fe/fe.h>
 #include <deal.II/fe/fe_dgq.h>
 #include <deal.II/fe/fe_tools.h>
@@ -102,6 +103,29 @@ FE_DGQ<dim, spacedim>::get_name () const
 
 
 
+template <int dim, int spacedim>
+void
+FE_DGQ<dim,spacedim>::
+convert_generalized_support_point_values_to_nodal_values (const std::vector<Vector<double> > &support_point_values,
+                                                          std::vector<double>                &nodal_values) const
+{
+  AssertDimension (support_point_values.size(),
+                   this->get_unit_support_points().size());
+  AssertDimension (support_point_values.size(),
+                   nodal_values.size());
+  AssertDimension (this->dofs_per_cell,
+                   nodal_values.size());
+
+  for (unsigned int i=0; i<this->dofs_per_cell; ++i)
+    {
+      AssertDimension (support_point_values[i].size(), 1);
+
+      nodal_values[i] = support_point_values[i](0);
+    }
+}
+
+
+
 template <int dim, int spacedim>
 FiniteElement<dim,spacedim> *
 FE_DGQ<dim, spacedim>::clone() const
@@ -759,6 +783,30 @@ FE_DGQArbitraryNodes<dim,spacedim>::get_name () const
 
 
 
+template <int dim, int spacedim>
+void
+FE_DGQArbitraryNodes<dim,spacedim>::
+convert_generalized_support_point_values_to_nodal_values (const std::vector<Vector<double> > &support_point_values,
+                                                          std::vector<double>                &nodal_values) const
+{
+  AssertDimension (support_point_values.size(),
+                   this->get_unit_support_points().size());
+  AssertDimension (support_point_values.size(),
+                   nodal_values.size());
+  AssertDimension (this->dofs_per_cell,
+                   nodal_values.size());
+
+  for (unsigned int i=0; i<this->dofs_per_cell; ++i)
+    {
+      AssertDimension (support_point_values[i].size(), 1);
+
+      nodal_values[i] = support_point_values[i](0);
+    }
+}
+
+
+
+
 template <int dim, int spacedim>
 FiniteElement<dim,spacedim> *
 FE_DGQArbitraryNodes<dim,spacedim>::clone() const
diff --git a/source/fe/fe_q.cc b/source/fe/fe_q.cc
index af64fe48c6..f0e272f4a4 100644
--- a/source/fe/fe_q.cc
+++ b/source/fe/fe_q.cc
@@ -1,6 +1,6 @@
 // ---------------------------------------------------------------------
 //
-// Copyright (C) 2000 - 2016 by the deal.II authors
+// Copyright (C) 2000 - 2017 by the deal.II authors
 //
 // This file is part of the deal.II library.
 //
@@ -15,6 +15,7 @@
 
 
 #include <deal.II/base/quadrature_lib.h>
+#include <deal.II/lac/vector.h>
 #include <deal.II/fe/fe_q.h>
 
 #include <vector>
@@ -132,6 +133,29 @@ FE_Q<dim,spacedim>::get_name () const
 
 
 
+template <int dim, int spacedim>
+void
+FE_Q<dim,spacedim>::
+convert_generalized_support_point_values_to_nodal_values (const std::vector<Vector<double> > &support_point_values,
+                                                          std::vector<double>                &nodal_values) const
+{
+  AssertDimension (support_point_values.size(),
+                   this->get_unit_support_points().size());
+  AssertDimension (support_point_values.size(),
+                   nodal_values.size());
+  AssertDimension (this->dofs_per_cell,
+                   nodal_values.size());
+
+  for (unsigned int i=0; i<this->dofs_per_cell; ++i)
+    {
+      AssertDimension (support_point_values[i].size(), 1);
+
+      nodal_values[i] = support_point_values[i](0);
+    }
+}
+
+
+
 template <int dim, int spacedim>
 FiniteElement<dim,spacedim> *
 FE_Q<dim,spacedim>::clone() const
-- 
2.39.5