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git-svn-id: https://svn.dealii.org/trunk@31637 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/include/deal.II/lac/block_sparse_matrix.h b/deal.II/include/deal.II/lac/block_sparse_matrix.h
index e5f91ad22bca386f38d681220828eee25ae6765e..75d3c5811e2d4e9d349c7ebc1e05e60a09f13d77 100644 (file)
--- a/deal.II/include/deal.II/lac/block_sparse_matrix.h
+++ b/deal.II/include/deal.II/lac/block_sparse_matrix.h
@@ -186,8 +186,11 @@ public:
    * sparsity patterns of the
    * parameter.
    *
-   * The elements of the matrix are
-   * set to zero by this function.
+   * You have to make sure that the lifetime of the sparsity structure is at
+   * least as long as that of this matrix or as long as reinit(const
+   * SparsityPattern &) is not called with a new sparsity structure.
+   *
+   * The elements of the matrix are set to zero by this function.
    */
   virtual void reinit (const BlockSparsityPattern &sparsity);
 //@}