From faa8cfa13f796e5ea22c64df751e7b7aa814fc63 Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Mon, 5 Nov 2012 00:56:21 +0000
Subject: [PATCH] Partial merge from the parallel_mg branch: Introduce a
 distribute_local_to_global function that writes a single element into a
 vector.

git-svn-id: https://svn.dealii.org/trunk@27381 0785d39b-7218-0410-832d-ea1e28bc413d
---
 .../include/deal.II/lac/constraint_matrix.h   | 64 ++++++++++++++-----
 1 file changed, 47 insertions(+), 17 deletions(-)

diff --git a/deal.II/include/deal.II/lac/constraint_matrix.h b/deal.II/include/deal.II/lac/constraint_matrix.h
index a79738f20e..6baf697998 100644
--- a/deal.II/include/deal.II/lac/constraint_matrix.h
+++ b/deal.II/include/deal.II/lac/constraint_matrix.h
@@ -1055,7 +1055,16 @@ class ConstraintMatrix : public Subscriptor
                                 VectorType                      &global_vector,
                                 const FullMatrix<double>        &local_matrix) const;
 
-
+				     /**
+				      * Enter a single value into a
+				      * result vector, obeying constraints.
+				      */
+    template <class VectorType>
+    void
+    distribute_local_to_global (unsigned int index,
+				double value,
+				VectorType        &global_vector) const;
+   
                                      /**
                                       * This function takes a pointer to a
                                       * vector of local contributions (@p
@@ -1983,30 +1992,36 @@ ConstraintMatrix::can_store_line (unsigned int line_index) const
 
 
 
-template <class InVector, class OutVector>
+template <class VectorType>
 inline
-void
-ConstraintMatrix::
-distribute_local_to_global (const InVector                  &local_vector,
-                            const std::vector<unsigned int> &local_dof_indices,
-                            OutVector                       &global_vector) const
+void ConstraintMatrix::distribute_local_to_global (
+  unsigned int index,
+  double value,
+  VectorType        &global_vector) const
 {
-  Assert (local_vector.size() == local_dof_indices.size(),
-          ExcDimensionMismatch(local_vector.size(), local_dof_indices.size()));
-  distribute_local_to_global (local_vector.begin(), local_vector.end(),
-                              local_dof_indices.begin(), global_vector);
+  Assert (sorted == true, ExcMatrixNotClosed());
+  
+  if (is_constrained(index) == false)
+    global_vector(index) += value;
+  else
+    {
+      const ConstraintLine& position =
+	lines[lines_cache[calculate_line_index(index)]];
+      for (unsigned int j=0; j<position.entries.size(); ++j)
+	global_vector(position.entries[j].first)
+	  += value * position.entries[j].second;
+    }
 }
 
 
-
 template <typename ForwardIteratorVec, typename ForwardIteratorInd,
           class VectorType>
 inline
-void ConstraintMatrix::
-  distribute_local_to_global (ForwardIteratorVec local_vector_begin,
-                              ForwardIteratorVec local_vector_end,
-                              ForwardIteratorInd local_indices_begin,
-                              VectorType        &global_vector) const
+void ConstraintMatrix::distribute_local_to_global (
+  ForwardIteratorVec local_vector_begin,
+  ForwardIteratorVec local_vector_end,
+  ForwardIteratorInd local_indices_begin,
+  VectorType        &global_vector) const
 {
   Assert (sorted == true, ExcMatrixNotClosed());
   for ( ; local_vector_begin != local_vector_end;
@@ -2026,6 +2041,21 @@ void ConstraintMatrix::
 }
 
 
+template <class InVector, class OutVector>
+inline
+void
+ConstraintMatrix::distribute_local_to_global (
+  const InVector                  &local_vector,
+  const std::vector<unsigned int> &local_dof_indices,
+  OutVector                       &global_vector) const
+{
+  Assert (local_vector.size() == local_dof_indices.size(),
+          ExcDimensionMismatch(local_vector.size(), local_dof_indices.size()));
+  distribute_local_to_global (local_vector.begin(), local_vector.end(),
+                              local_dof_indices.begin(), global_vector);
+}
+
+
 
 template <typename ForwardIteratorVec, typename ForwardIteratorInd,
           class VectorType>
-- 
2.39.5