From dfb674a25ead137118eebf0230c4c8a4c81db5d0 Mon Sep 17 00:00:00 2001
From: Gael Guennebaud <g.gael@free.fr>
Date: Tue, 31 Mar 2015 20:17:10 +0200
Subject: Make reverseInPlace really work in-place.

---
 Eigen/src/Core/Reverse.h | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

(limited to 'Eigen/src/Core/Reverse.h')

diff --git a/Eigen/src/Core/Reverse.h b/Eigen/src/Core/Reverse.h
index 291300a4a..b3fba9704 100644
--- a/Eigen/src/Core/Reverse.h
+++ b/Eigen/src/Core/Reverse.h
@@ -210,7 +210,26 @@ DenseBase<Derived>::reverse() const
 template<typename Derived>
 inline void DenseBase<Derived>::reverseInPlace()
 {
-  derived() = derived().reverse().eval();
+  if(cols()>rows())
+  {
+    Index half = cols()/2;
+    leftCols(half).swap(rightCols(half).reverse());
+    if((cols()%2)==1)
+    {
+      Index half2 = rows()/2;
+      col(half).head(half2).swap(col(half).tail(half2).reverse());
+    }
+  }
+  else
+  {
+    Index half = rows()/2;
+    topRows(half).swap(bottomRows(half).reverse());
+    if((rows()%2)==1)
+    {
+      Index half2 = cols()/2;
+      row(half).head(half2).swap(row(half).tail(half2).reverse());
+    }
+  }
 }
 
 } // end namespace Eigen
-- 
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