From a6803742ece5afdfe163df61859f7b17b71ddade Mon Sep 17 00:00:00 2001
From: Baerbel Jannsen <baerbel.janssen@gmail.com>
Date: Thu, 11 Mar 2010 19:27:29 +0000
Subject: [PATCH] PreconditionIdentiy now provides the interface for use in a
 smoother for MG

git-svn-id: https://svn.dealii.org/trunk@20800 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/lac/include/lac/precondition.h | 44 ++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/deal.II/lac/include/lac/precondition.h b/deal.II/lac/include/lac/precondition.h
index 57582ecf81..e61b60a28c 100644
--- a/deal.II/lac/include/lac/precondition.h
+++ b/deal.II/lac/include/lac/precondition.h
@@ -55,6 +55,33 @@ template <typename number> class SparseMatrix;
 class PreconditionIdentity : public Subscriptor
 {
   public:
+
+				     /**
+				      * This function is only 
+                                      * present to 
+                                      * provide the interface of
+                                      * a precondtioner to be 
+                                      * handed to a smoother.
+                                      * This does nothing.
+				      */
+  struct AdditionalData
+  {
+                                       /**
+					* Constructor.
+					*/
+    AdditionalData (){}
+  };
+
+				     /**
+				      * The matrix
+				      * argument is ignored and here
+				      * just for compatibility with
+				      * more complex preconditioners.
+				      */
+  template <class MATRIX>
+  void initialize (const MATRIX         &matrix,
+		   const AdditionalData &additional_data = AdditionalData());
+
 				     /**
 				      * Apply preconditioner.
 				      */
@@ -86,6 +113,16 @@ class PreconditionIdentity : public Subscriptor
 				      */
     template<class VECTOR>
     void Tvmult_add (VECTOR&, const VECTOR&) const;
+
+				     /**
+				      * This function is only 
+                                      * present to 
+                                      * provide the interface of
+                                      * a precondtioner to be 
+                                      * handed to a smoother.
+                                      * This does nothing.
+				      */
+    void clear (){}
 };
 
 
@@ -1028,6 +1065,13 @@ class PreconditionChebyshev : public Subscriptor
 
 #ifndef DOXYGEN
 
+template <class MATRIX>
+inline void
+PreconditionIdentity::initialize (
+  const MATRIX&,
+  const PreconditionIdentity::AdditionalData&)
+{}
+
 
 template<class VECTOR>
 inline void
-- 
2.39.5