Hi! I'm not sure but I think, that the function computing Katz Centrality - void central_katz() is not correct. I do not think that this formula is correct:

               C[i] = 0.0;
               for(int j=0;j<NV;++j) if(i!=j)
                       C[i] += pow(alpha,dist[i+NV*j]);

Assuming that 'alpha' is decay factor and 'dist[i+NV*j]' is shortest path from i to j.

Regards

Przemek