Hello there,

I started using Boost graph library recently for one of my projects.I was trying to implement dijkstra's shortest path algorithm with the help of the following function,

dijkstra_shortest_paths
    (G, vertex(a, G), 
     distance_map(make_iterator_property_map(distance.begin(), vertex_id, 
                                             distance[0])).
     predecessor_map(make_iterator_property_map(parent.begin(), vertex_id,
                                                parent[0])).
     visitor(make_dijkstra_visitor(copy_graph(G_copy, on_examine_edge()))));

But while comparing the definition of the function as in http://www.boost.org/doc/libs/1_55_0/libs/graph/doc/dijkstra_shortest_paths.html, to the above written function,it doesnt make sense,

especially the third argument of the above written function.Can anyone help me with this?

Thanks in advance.