Return the Estrada index of a the graph G.
Parameters: | G: graph : |
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Returns: | estrada index: float : |
Raises: | NetworkXError :
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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
References
[R189] | 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)