[igraph] Modularity on the igraph_community_spinglass()

[Guilherme Ferraz de Arruda]

Hi,

I have a doubt about the modularity function implemented on the igraph_community_spinglass() function for weighted graphs. It is normalized on the number of edges or the sum of edge weights?

I got some negative values, like -2, for some graphs.

Is it correct? On the unweighted case the modularity varys between -1 to 1. But on the weighted generalization I think that it is not true.

Thanks a lot!

Guilherme.