From 7458364c57d185337f99a1dbf81e283dc642dc29 Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@math.tamu.edu>
Date: Thu, 3 Jun 2004 04:27:53 +0000
Subject: [PATCH] Fix small problem where clear() didn't do what it was
 supposed to do.

git-svn-id: https://svn.dealii.org/trunk@9368 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/doc/news/c-5.0.html                 | 10 ++++++++++
 deal.II/lac/include/lac/block_matrix_base.h |  3 ++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/deal.II/doc/news/c-5.0.html b/deal.II/doc/news/c-5.0.html
index 671e5c190c..15d2422e37 100644
--- a/deal.II/doc/news/c-5.0.html
+++ b/deal.II/doc/news/c-5.0.html
@@ -86,6 +86,16 @@ inconvenience this causes.
 <h3>lac</h3>
 
 <ol>
+  <li> <p>
+       Fixed: <code class="member">BlockSparseMatrix::clear()</code> did not
+       do what it was supposed to do: it emptied the individual blocks and
+       removed them, but it still kept the number of blocks
+       unchanged. Subsequent accesses to these blocks, or to their information
+       yielded segmentation faults.
+       <br> 
+       (WB 2004/06/02)
+       </p>
+
   <li> <p>
        New: Block matrices and vectors have been factored into abstract base
        classes and concrete implementation classes. While the previous classes
diff --git a/deal.II/lac/include/lac/block_matrix_base.h b/deal.II/lac/include/lac/block_matrix_base.h
index 2fe4402d2b..99b49b3d64 100644
--- a/deal.II/lac/include/lac/block_matrix_base.h
+++ b/deal.II/lac/include/lac/block_matrix_base.h
@@ -1076,7 +1076,8 @@ BlockMatrixBase<MatrixType>::clear ()
   for (unsigned int r=0; r<n_block_rows(); ++r)
     for (unsigned int c=0; c<n_block_cols(); ++c)
       block(r,c).clear ();
-  sub_objects.clear ();
+  sub_objects.reinit (0,0);
+  row_block_indices = column_block_indices = BlockIndices();
 
                                    // reset block indices to empty
   row_block_indices = column_block_indices = BlockIndices ();
-- 
2.39.5