From 2017955d089c74a675d6e752c38b731ebd6fc38d Mon Sep 17 00:00:00 2001
From: Markus Blatt <markus@dr-blatt.de>
Date: Thu, 8 Dec 2022 13:56:51 +0100
Subject: [PATCH] Fixes implicit build mode of BCRSMatrix with zero rows.
Corner case that sometimes happens and produced a segmentation fault.
---
dune/istl/bcrsmatrix.hh | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/dune/istl/bcrsmatrix.hh b/dune/istl/bcrsmatrix.hh
index 9384fcdf6..987acf612 100644
--- a/dune/istl/bcrsmatrix.hh
+++ b/dune/istl/bcrsmatrix.hh
@@ -1465,10 +1465,18 @@ namespace Dune {
overflow.clear();
//determine average number of entries and memory usage
- std::ptrdiff_t diff = (r[n-1].getindexptr() + r[n-1].getsize() - j_.get());
- nnz_ = diff;
- stats.avg = (double) (nnz_) / (double) n;
- stats.mem_ratio = (double) (nnz_) / (double) allocationSize_;
+ if ( n == 0)
+ {
+ stats.avg = 0;
+ stats.mem_ratio = 1;
+ }
+ else
+ {
+ std::ptrdiff_t diff = (r[n-1].getindexptr() + r[n-1].getsize() - j_.get());
+ nnz_ = diff;
+ stats.avg = (double) (nnz_) / (double) n;
+ stats.mem_ratio = (double) (nnz_) / (double) allocationSize_;
+ }
//matrix is now built
ready = built;
--
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