Return the Estrada index of a the graph G.
Parameters : | G: graph : |
---|---|
Returns : | estrada index: float : |
Raises : | NetworkXError :
|
See also
estrada_index_exp
Notes
Let G=(V,E) be a simple undirected graph with n nodes and let \lambda_{1}\leq\lambda_{2}\leq\cdots\lambda_{n} be a non-increasing ordering of the eigenvalues of its adjacency matrix A. The Estrada index is
EE(G)=\sum_{j=1}^n e^{\lambda _j}.
References
[R174] | E. Estrada, Characterization of 3D molecular structure, Chem. Phys. Lett. 319, 713 (2000). |
Examples
>>> G=nx.Graph([(0,1),(1,2),(1,5),(5,4),(2,4),(2,3),(4,3),(3,6)])
>>> ei=nx.estrada_index(G)