diff --git a/include/boost/polygon/detail/polygon_arbitrary_formation.hpp b/include/boost/polygon/detail/polygon_arbitrary_formation.hpp
index 1cdb706..e1acdbb 100644
--- a/include/boost/polygon/detail/polygon_arbitrary_formation.hpp
+++ b/include/boost/polygon/detail/polygon_arbitrary_formation.hpp
@@ -326,12 +326,11 @@ namespace boost { namespace polygon{
           } else if(elm1y == elm2y) {
             if(elm1 == elm2)
               return false;
-            typedef typename coordinate_traits<Unit>::manhattan_area_type at;
-            at dx1 = at(elm1.second.get(HORIZONTAL)) - at(elm1.first.get(HORIZONTAL));
-            at dy1 = at(elm1.second.get(VERTICAL)) - at(elm1.first.get(VERTICAL));
-            at dx2 = at(elm2.second.get(HORIZONTAL)) - at(elm2.first.get(HORIZONTAL));
-            at dy2 = at(elm2.second.get(VERTICAL)) - at(elm2.first.get(VERTICAL));
-            retval = ((*justBefore_) != 0) ^ less_slope(dx1, dy1, dx2, dy2);
+            retval = less_slope(elm1.second.get(HORIZONTAL) - elm1.first.get(HORIZONTAL),
+                                     elm1.second.get(VERTICAL) - elm1.first.get(VERTICAL),
+                                     elm2.second.get(HORIZONTAL) - elm2.first.get(HORIZONTAL),
+                                     elm2.second.get(VERTICAL) - elm2.first.get(VERTICAL));
+            retval = ((*justBefore_) != 0) ^ retval;
           }
         }
         return retval;
@@ -827,12 +826,11 @@ namespace boost { namespace polygon{
           } else if(elm1y == elm2y) {
             if(elm1.pt == elm2.pt && elm1.other_pt == elm2.other_pt)
               return false;
-            typedef typename coordinate_traits<Unit>::manhattan_area_type at;
-            at dx1 = at(elm1.other_pt.get(HORIZONTAL)) - at(elm1.pt.get(HORIZONTAL));
-            at dy1 = at(elm1.other_pt.get(VERTICAL)) - at(elm1.pt.get(VERTICAL));
-            at dx2 = at(elm2.other_pt.get(HORIZONTAL)) - at(elm2.pt.get(HORIZONTAL));
-            at dy2 = at(elm2.other_pt.get(VERTICAL)) - at(elm2.pt.get(VERTICAL));
-            retval = ((*justBefore_) != 0) ^ less_slope(dx1, dy1, dx2, dy2);
+            retval = less_slope(elm1.other_pt.get(HORIZONTAL) - elm1.pt.get(HORIZONTAL),
+                                     elm1.other_pt.get(VERTICAL) - elm1.pt.get(VERTICAL),
+                                     elm2.other_pt.get(HORIZONTAL) - elm2.pt.get(HORIZONTAL),
+                                     elm2.other_pt.get(VERTICAL) - elm2.pt.get(VERTICAL));
+            retval = ((*justBefore_) != 0) ^ retval;
           }
         }
         return retval;
@@ -1235,11 +1233,10 @@ namespace boost { namespace polygon{
       inline less_incoming_count(Point point) : pt_(point) {}
       inline bool operator () (const std::pair<std::pair<std::pair<Point, Point>, int>, active_tail_arbitrary*>& elm1,
                                const std::pair<std::pair<std::pair<Point, Point>, int>, active_tail_arbitrary*>& elm2) const {
-        typedef typename coordinate_traits<Unit>::manhattan_area_type at;
-        at dx1 = at(elm1.first.first.first.get(HORIZONTAL)) - at(elm1.first.first.second.get(HORIZONTAL));
-        at dx2 = at(elm2.first.first.first.get(HORIZONTAL)) - at(elm2.first.first.second.get(HORIZONTAL));
-        at dy1 = at(elm1.first.first.first.get(VERTICAL)) - at(elm1.first.first.second.get(VERTICAL));
-        at dy2 = at(elm2.first.first.first.get(VERTICAL)) - at(elm2.first.first.second.get(VERTICAL));
+        Unit dx1 = elm1.first.first.first.get(HORIZONTAL) - elm1.first.first.second.get(HORIZONTAL);
+        Unit dx2 = elm2.first.first.first.get(HORIZONTAL) - elm2.first.first.second.get(HORIZONTAL);
+        Unit dy1 = elm1.first.first.first.get(VERTICAL) - elm1.first.first.second.get(VERTICAL);
+        Unit dy2 = elm2.first.first.first.get(VERTICAL) - elm2.first.first.second.get(VERTICAL);
         return scanline_base<Unit>::less_slope(dx1, dy1, dx2, dy2);
       }
     };
diff --git a/include/boost/polygon/point_data.hpp b/include/boost/polygon/point_data.hpp
index e37f82f..23c23ed 100644
--- a/include/boost/polygon/point_data.hpp
+++ b/include/boost/polygon/point_data.hpp
@@ -46,7 +46,7 @@ class point_data {
   }
 
   template <typename PointType>
-  explicit point_data(const PointType& that) {
+  point_data(const PointType& that) {
     *this = that;
   }
 
diff --git a/include/boost/polygon/polygon_traits.hpp b/include/boost/polygon/polygon_traits.hpp
index b4d0e9d..6055bc7 100644
--- a/include/boost/polygon/polygon_traits.hpp
+++ b/include/boost/polygon/polygon_traits.hpp
@@ -1418,18 +1418,6 @@ namespace boost { namespace polygon{
   }
   */
 
-  template <typename T1, typename T2>
-  typename enable_if<
-    typename gtl_and< typename is_mutable_point_concept<typename geometry_concept<T1>::type>::type,
-                      typename is_polygon_with_holes_type<T2>::type>::type,
-    bool>::type
-  center(T1& center_point, const T2& polygon) {
-    typedef typename polygon_traits<T2>::coordinate_type coordinate_type;
-    rectangle_data<coordinate_type> bbox;
-    extents(bbox, polygon);
-    return center(center_point, bbox);
-  }
-
   template <typename T1, typename T2>
   typename enable_if<
     typename gtl_and< typename is_mutable_rectangle_concept<typename geometry_concept<T1>::type>::type,
@@ -1451,6 +1439,18 @@ namespace boost { namespace polygon{
     return true;
   }
 
+  template <typename T1, typename T2>
+  typename enable_if<
+    typename gtl_and< typename is_mutable_point_concept<typename geometry_concept<T1>::type>::type,
+                      typename is_polygon_with_holes_type<T2>::type>::type,
+    bool>::type
+  center(T1& center_point, const T2& polygon) {
+    typedef typename polygon_traits<T2>::coordinate_type coordinate_type;
+    rectangle_data<coordinate_type> bbox;
+    extents(bbox, polygon);
+    return center(center_point, bbox);
+  }
+
   template <class T>
   template <class T2>
   polygon_90_data<T>& polygon_90_data<T>::operator=(const T2& rvalue) {