What is the rationale behind division by 2 for the undirected Brandes calcuation? Also, can someone show me how to get the weighted version of brandes? The following code calculates the unweighted version. #include "boost/graph/adjacency_list.hpp" #include "boost/graph/graph_utility.hpp" #include "boost/graph/betweenness_centrality.hpp" using namespace boost; int main(int argc, char * argv[]){ const int N = 6; typedef property < edge_weight_t, double > WeightMap; typedef property < vertex_centrality_t, double > CentralityMap; typedef adjacency_list<vecS, vecS, undirectedS, CentralityMap, WeightMap> UndirectedGraph; UndirectedGraph g(N); add_edge(0, 1, 3, g); add_edge(0, 2, 2, g); add_edge(0, 3, 6, g); add_edge(0, 4, 4, g); add_edge(1, 3, 5, g); add_edge(1, 5, 5, g); add_edge(2, 4, 1, g); add_edge(3, 4, 2, g); add_edge(3, 5, 1, g); add_edge(4, 5, 4, g); print_graph(g); brandes_betweenness_centrality(g, get(vertex_centrality,g), get(edge_weight, g) ); boost::property_map<UndirectedGraph, vertex_centrality_t>::type b = get(vertex_centrality, g); graph_traits < UndirectedGraph >::vertex_iterator vi, vi_end; for (tie(vi, vi_end) = vertices(g); vi != vi_end; ++vi) { printf("BRANDES centr[%d] = %g\n", *vi, b[*vi]); } } Boost/graph gives the following: 0 <--> 1 2 3 4 1 <--> 0 3 5 2 <--> 0 4 3 <--> 0 1 4 5 4 <--> 0 2 3 5 5 <--> 1 3 4 I AM HERE dispatch2 CALLING UNWEIGHTED BRANDES centr[0] = 1.83333 BRANDES centr[1] = 0.333333 BRANDES centr[2] = 0 BRANDES centr[3] = 0.666667 BRANDES centr[4] = 1.83333 BRANDES centr[5] = 0.333333 While networkx gives: http://networkx.lanl.gov/reference/generated/networkx.betweenness_centrality... {0: 3.6666666666666665, 1: 0.66666666666666663, 2: 0.0, 3: 1.3333333333333333, 4: 3.6666666666666661, 5: 0.66666666666666663} So, boost is exactly 1/2 of networkx's solution. Is one version wrong? Or is this some kind of convention that boost and networkx disagree on? Thanks, Matt