From b96d414854587943ce870eeeb7c2caa803ea726b Mon Sep 17 00:00:00 2001
From: guido <guido@0785d39b-7218-0410-832d-ea1e28bc413d>
Date: Wed, 6 Dec 2000 16:41:04 +0000
Subject: [PATCH] BlockDiagonalMatrix

git-svn-id: https://svn.dealii.org/trunk@3524 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/lac/include/lac/block_matrix.h | 114 +++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 deal.II/lac/include/lac/block_matrix.h

diff --git a/deal.II/lac/include/lac/block_matrix.h b/deal.II/lac/include/lac/block_matrix.h
new file mode 100644
index 0000000000..ac4c7fc99f
--- /dev/null
+++ b/deal.II/lac/include/lac/block_matrix.h
@@ -0,0 +1,114 @@
+//-------------------------------------------------------------------
+//    $Id$
+//    Version: $Name$
+//
+//    Copyright (C) 1998, 1999, 2000 by the deal.II authors
+//
+//    This file is subject to QPL and may not be  distributed
+//    without copyright and license information. Please refer
+//    to the file deal.II/doc/license.html for the  text  and
+//    further information on this license.
+//
+//-------------------------------------------------------------------
+#ifndef __deal2__block_matrix_h
+#define __deal2__block_matrix_h
+
+
+#include <base/exceptions.h>
+#include <base/smartpointer.h>
+#include <lac/block_vector.h>
+
+/**
+ * A matrix with several copies of the same block on the diagonal.
+ *
+ * This matrix implements an @p{m} by @p{m} block matrix. Each
+ * diagonal block consists of the same (non-block) matrix, while
+ * off-diagonal blocks are void.
+ *
+ * One special application is a one by one block matrix, allowing to
+ * apply the @p{vmult} of the original matrix (or preconditioner) to a
+ * block vector.
+ *
+ * @author Guido Kanschat, 2000
+ */
+template <class MATRIX>
+class BlockDiagonalMatrix : public Subscriptor
+{
+public:
+				   /**
+				    * Constructor for an @p{n_blocks}
+				    * by @p{n_blocks} matrix with
+				    * diagonal blocks @p{M}.
+				    */
+  BlockDiagonalMatrix (const MATRIX& M,
+		       unsigned int n_blocks);
+
+				   /**
+				    * Matrix-vector-multiplication.
+				    */
+  template <typename number1, typename number2>
+  void vmult (BlockVector<number1>& dst,
+	      const BlockVector<number2>& src) const;
+  
+				   /**
+				    * Transposed matrix-vector-multiplication.
+				    */
+  template <typename number1, typename number2>
+  void Tvmult (BlockVector<number1>& dst,
+	       const BlockVector<number2>& src) const;
+private:
+				   /**
+				    * Number of blocks.
+				    */
+  unsigned int num_blocks;
+				   /**
+				    * Diagonal entry.
+				    */
+  SmartPointer<const MATRIX> matrix;
+};
+
+
+//----------------------------------------------------------------------//
+
+template <class MATRIX>
+BlockDiagonalMatrix<MATRIX>::BlockDiagonalMatrix (const MATRIX& M,
+						  unsigned int num_blocks)
+  : num_blocks (num_blocks),
+    matrix(&M)
+{}
+
+
+template <class MATRIX>
+template <typename number1, typename number2>
+void
+BlockDiagonalMatrix<MATRIX>::vmult (BlockVector<number1>& dst,
+				     const BlockVector<number2>& src) const
+{
+  Assert (dst.n_blocks()==num_blocks,
+	  ExcDimensionMismatch(dst.n_blocks(),num_blocks));
+  Assert (src.n_blocks()==num_blocks,
+	  ExcDimensionMismatch(src.n_blocks(),num_blocks));
+
+  for (unsigned int i=0;i<num_blocks;++i)
+    matrix->vmult (dst.block(i), src.block(i));
+}
+
+
+template <class MATRIX>
+template <typename number1, typename number2>
+void
+BlockDiagonalMatrix<MATRIX>::Tvmult (BlockVector<number1>& dst,
+				     const BlockVector<number2>& src) const
+{
+  Assert (dst.n_blocks()==num_blocks,
+	  ExcDimensionMismatch(dst.n_blocks(),num_blocks));
+  Assert (src.n_blocks()==num_blocks,
+	  ExcDimensionMismatch(src.n_blocks(),num_blocks));
+
+  for (unsigned int i=0;i<num_blocks;++i)
+    matrix->Tvmult (dst.block(i), src.block(i));
+}
+
+
+#endif
+
-- 
2.39.5