Index: vector_sparse.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/numeric/ublas/vector_sparse.hpp,v
retrieving revision 1.76
diff -u -r1.76 vector_sparse.hpp
--- vector_sparse.hpp	4 Feb 2006 15:13:25 -0000	1.76
+++ vector_sparse.hpp	3 Nov 2006 22:05:44 -0000
@@ -868,13 +868,21 @@
     public:
         BOOST_UBLAS_INLINE
         void resize (size_type size, bool preserve = true) {
-            // FIXME preserve unimplemented
-            BOOST_UBLAS_CHECK (!preserve, internal_logic ());
-            size_ = size;
             capacity_ = restrict_capacity (capacity_);
-            index_data_. resize (capacity_);
-            value_data_. resize (capacity_);
-            filled_ = 0;
+            if (preserve) {
+                index_data_. resize (capacity_, size_type ());
+                value_data_. resize (capacity_, value_type ());
+                filled_ = (std::min) (capacity_, filled_);
+                while (filled_ && (zero_based(index_data_[filled_ - 1]) >= size)) {
+                    --filled_;
+                }
+            }
+            else {
+                index_data_. resize (capacity_);
+                value_data_. resize (capacity_);
+                filled_ = 0;
+            }
+            size_ = size;
             storage_invariants ();
         }
 
@@ -1316,6 +1324,7 @@
             BOOST_UBLAS_CHECK (capacity_ == index_data_.size (), internal_logic ());
             BOOST_UBLAS_CHECK (capacity_ == value_data_.size (), internal_logic ());
             BOOST_UBLAS_CHECK (filled_ <= capacity_, internal_logic ());
+            BOOST_UBLAS_CHECK (!filled_ || (zero_based(index_data_[filled_ - 1]) < size_), internal_logic ());
         }
 
         size_type size_;