Function spectral_radius 

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

Compute the spectral radius of a graph.

ρ(G) = max_i |λ_i| — the largest eigenvalue in absolute value. For undirected graphs, this equals λ_1 (the largest eigenvalue).

Returns 0.0 for an empty graph.

Examples

use rust_igraph::{Graph, spectral_radius};

// K_3: eigenvalues {2, -1, -1} → spectral radius = 2
let g = Graph::from_edges(&[(0,1),(1,2),(0,2)], false, Some(3)).unwrap();
let rho = spectral_radius(&g).unwrap();
assert!((rho - 2.0).abs() < 0.01);