From ebde55caabf73acdca7a584df4dbd512e866b8ac Mon Sep 17 00:00:00 2001
From: Aaron Windsor <aaron.windsor@gmail.com>
Date: Thu, 16 Oct 2008 12:02:37 +0000
Subject: [PATCH] Patch from David Gleich to fix underflow and overflow that
 can happen when computing vertex positions in
 chroback_payne_straight_line_drawing

[SVN r49358]
---
 include/boost/graph/chrobak_payne_drawing.hpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/boost/graph/chrobak_payne_drawing.hpp b/include/boost/graph/chrobak_payne_drawing.hpp
index 6fb7b56d..e8a9104b 100644
--- a/include/boost/graph/chrobak_payne_drawing.hpp
+++ b/include/boost/graph/chrobak_payne_drawing.hpp
@@ -193,8 +193,8 @@ namespace boost
             delta_p_q += delta_x[temp];
           }
 
-        delta_x[v] = (y[rightmost] - y[leftmost] + delta_p_q)/2;
-        y[v] = (y[rightmost] + y[leftmost] + delta_p_q)/2;
+        delta_x[v] = ((y[rightmost] + delta_p_q) - y[leftmost])/2;
+        y[v] = y[leftmost] + delta_x[v];
         delta_x[rightmost] = delta_p_q - delta_x[v];
         
         bool leftmost_and_rightmost_adjacent = right[leftmost] == rightmost;