Function second_ev_degree_zagreb 

pub fn second_ev_degree_zagreb(graph: &Graph) -> IgraphResult<u64>

Compute the second ev-degree Zagreb index.

M₂^{ev}(G) = Σ_{e~f, adjacent} d_{ev}(e) · d_{ev}(f)

Two edges are adjacent if they share exactly one endpoint.

Examples

use rust_igraph::{Graph, second_ev_degree_zagreb};

// K_3: 3 edges with d_ev=2 each, 3 adjacent pairs, M₂ev = 3×4 = 12
let g = Graph::from_edges(&[(0,1),(1,2),(0,2)], false, Some(3)).unwrap();
assert_eq!(second_ev_degree_zagreb(&g).unwrap(), 12);