From: kronbichler <kronbichler@0785d39b-7218-0410-832d-ea1e28bc413d>
Date: Wed, 18 Feb 2009 12:14:56 +0000 (+0000)
Subject: When Trilinos matrices are based on the same sparsity pattern, they can share the... 
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=015488d4861b674bb369977481bd62f3066b991f;p=dealii-svn.git

When Trilinos matrices are based on the same sparsity pattern, they can share the SP data if we initialize them correctly. This has been applied to step-31.

git-svn-id: https://svn.dealii.org/trunk@18394 0785d39b-7218-0410-832d-ea1e28bc413d
---

diff --git a/deal.II/examples/step-31/step-31.cc b/deal.II/examples/step-31/step-31.cc
index 0d1da76c16..eead40b517 100644
--- a/deal.II/examples/step-31/step-31.cc
+++ b/deal.II/examples/step-31/step-31.cc
@@ -1272,7 +1272,19 @@ void BoussinesqFlowProblem<dim>::setup_dofs ()
 				   // of the Stokes matrix &ndash; except
 				   // that it is much easier here since we
 				   // do not need to take care of any blocks
-				   // or coupling between components:
+				   // or coupling between components. Note
+				   // how we initialize the three
+				   // temperature matrices: We only use the
+				   // sparsity pattern for reinitialization
+				   // of the first matrix, whereas we use
+				   // the previously generated matrix for
+				   // the two remaining reinits. The reason
+				   // for doing so is that reinitialization
+				   // from an already generated matrix
+				   // allows Trilinos to reuse the sparsity
+				   // pattern instead of generating a new
+				   // one for each copy. This saves both
+				   // some time and memory.
   {
     temperature_mass_matrix.clear ();
     temperature_stiffness_matrix.clear ();
@@ -1283,8 +1295,8 @@ void BoussinesqFlowProblem<dim>::setup_dofs ()
 				     temperature_constraints, false);
 
     temperature_matrix.reinit (csp);
-    temperature_mass_matrix.reinit (csp);
-    temperature_stiffness_matrix.reinit (csp);
+    temperature_mass_matrix.reinit (temperature_matrix);
+    temperature_stiffness_matrix.reinit (temperature_matrix);
   }
 
 				   // Lastly, we set the vectors for the
diff --git a/deal.II/lac/include/lac/trilinos_sparse_matrix.h b/deal.II/lac/include/lac/trilinos_sparse_matrix.h
index ecd9b56e96..922aa01c29 100755
--- a/deal.II/lac/include/lac/trilinos_sparse_matrix.h
+++ b/deal.II/lac/include/lac/trilinos_sparse_matrix.h
@@ -2,7 +2,7 @@
 //    $Id$
 //    Version: $Name$
 //
-//    Copyright (C) 2008 by the deal.II authors
+//    Copyright (C) 2008, 2009 by the deal.II authors
 //
 //    This file is subject to QPL and may not be  distributed
 //    without copyright and license information. Please refer
@@ -290,7 +290,7 @@ namespace TrilinosWrappers
  * 
  * @ingroup TrilinosWrappers
  * @ingroup Matrix1
- * @author Martin Kronbichler, Wolfgang Bangerth, 2008
+ * @author Martin Kronbichler, Wolfgang Bangerth, 2008, 2009
  */
   class SparseMatrix : public Subscriptor
   {
diff --git a/deal.II/lac/source/trilinos_sparse_matrix.cc b/deal.II/lac/source/trilinos_sparse_matrix.cc
index 580bcb552b..74de21cb8e 100755
--- a/deal.II/lac/source/trilinos_sparse_matrix.cc
+++ b/deal.II/lac/source/trilinos_sparse_matrix.cc
@@ -2,7 +2,7 @@
 //    $Id$
 //    Version: $Name$
 //
-//    Copyright (C) 2008 by the deal.II authors
+//    Copyright (C) 2008, 2009 by the deal.II authors
 //
 //    This file is subject to QPL and may not be  distributed
 //    without copyright and license information. Please refer
@@ -251,6 +251,7 @@ namespace TrilinosWrappers
     row_map = m.row_map;
     col_map = m.col_map;
     *matrix = *m.matrix;
+    compress();
     return *this;
   }
   
@@ -563,9 +564,10 @@ namespace TrilinosWrappers
 
     row_map = sparse_matrix.row_map;
     col_map = sparse_matrix.col_map;
-    matrix = std::auto_ptr<Epetra_FECrsMatrix>(new Epetra_FECrsMatrix(
-				                   *sparse_matrix.matrix));
-    compressed = true;
+    matrix = std::auto_ptr<Epetra_FECrsMatrix>
+      (new Epetra_FECrsMatrix(Copy, sparse_matrix.matrix->Graph(), false));
+
+    compress();
   }