Function exponential_inverse_degree 

pub fn exponential_inverse_degree(graph: &Graph) -> IgraphResult<f64>

Compute the exponential inverse degree index.

eID(G) = Σ_v e^{1/d(v)} for d(v) > 0.

Vertices with degree 0 are skipped. Returns 0.0 for edgeless graphs.

Examples

use rust_igraph::{Graph, exponential_inverse_degree};

// K_3: 3 vertices with d=2 → 3·e^{0.5}
let g = Graph::from_edges(&[(0,1),(1,2),(0,2)], false, Some(3)).unwrap();
assert!((exponential_inverse_degree(&g).unwrap() - 3.0 * 0.5_f64.exp()).abs() < 1e-10);