From 548217283fd84f7b9eef0598c3acd9285ec97547 Mon Sep 17 00:00:00 2001
From: bangerth <bangerth@0785d39b-7218-0410-832d-ea1e28bc413d>
Date: Tue, 12 Feb 2013 16:09:54 +0000
Subject: [PATCH] Follow the documented advice of not looping over all elements
 of a matrix but do so row by row.

git-svn-id: https://svn.dealii.org/trunk@28330 0785d39b-7218-0410-832d-ea1e28bc413d
---
 deal.II/include/deal.II/lac/full_matrix.h | 30 +++++++++++++++++------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/deal.II/include/deal.II/lac/full_matrix.h b/deal.II/include/deal.II/lac/full_matrix.h
index 6a2854ef91..6fab9285d2 100644
--- a/deal.II/include/deal.II/lac/full_matrix.h
+++ b/deal.II/include/deal.II/lac/full_matrix.h
@@ -1520,10 +1520,17 @@ void
 FullMatrix<number>::copy_from (const MATRIX &M)
 {
   this->reinit (M.m(), M.n());
-  const typename MATRIX::const_iterator end = M.end();
-  for (typename MATRIX::const_iterator entry = M.begin();
-       entry != end; ++entry)
-    this->el(entry->row(), entry->column()) = entry->value();
+
+  // loop over the elements of the argument matrix row by row, as suggested
+  // in the documentation of the sparse matrix iterator class, and
+  // copy them into the current object
+  for (unsigned int row = 0; row < M.n(); ++row)
+    {
+      const typename MATRIX::const_iterator end_row = M.end(row);
+      for (typename MATRIX::const_iterator entry = M.begin(row);
+          entry != end_row; ++entry)
+        this->el(row, entry->column()) = entry->value();
+    }
 }
 
 
@@ -1534,10 +1541,17 @@ void
 FullMatrix<number>::copy_transposed (const MATRIX &M)
 {
   this->reinit (M.n(), M.m());
-  const typename MATRIX::const_iterator end = M.end();
-  for (typename MATRIX::const_iterator entry = M.begin();
-       entry != end; ++entry)
-    this->el(entry->column(), entry->row()) = entry->value();
+
+  // loop over the elements of the argument matrix row by row, as suggested
+  // in the documentation of the sparse matrix iterator class, and
+  // copy them into the current object
+  for (unsigned int row = 0; row < M.n(); ++row)
+    {
+      const typename MATRIX::const_iterator end_row = M.end(row);
+      for (typename MATRIX::const_iterator entry = M.begin(row);
+          entry != end_row; ++entry)
+        this->el(entry->column(), row) = entry->value();
+    }
 }
 
 
-- 
2.39.5