--- vector_expression.hpp.orig	2008-05-13 14:16:29.000000000 +0100
+++ vector_expression.hpp	2008-06-10 17:38:44.748916000 +0100
@@ -10,6 +10,10 @@
 //  GeNeSys mbH & Co. KG in producing this work.
 //
 
+// Modified vector_reference to construct reference<const E> from reference<E>
+//                                properly, by Kian Ming A. Chai (10 Jun 2008) 
+
+
 #ifndef _BOOST_UBLAS_VECTOR_EXPRESSION_
 #define _BOOST_UBLAS_VECTOR_EXPRESSION_
 
@@ -49,12 +53,29 @@ namespace boost { namespace numeric { na
         explicit vector_reference (referred_type &e):
             e_ (e) {}
 
+      
+        // Construction from a reference to a non-const E
+        template <typename nonconstE>
+        BOOST_UBLAS_INLINE
+        explicit vector_reference (const vector_reference<nonconstE> &e, 
+				   typename boost::enable_if_c<
+                                         boost::is_const<E>::value &&
+				         boost::is_same<typename boost::remove_const<E>::type,
+				                        nonconstE>::value>::type* = 0):
+	  e_(e.expression()) 
+        {}
+
         // Accessors
         BOOST_UBLAS_INLINE
         size_type size () const {
             return expression ().size ();
         }