Function multiplicative_ga 

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

Compute the multiplicative geometric-arithmetic index.

Πga(G) = Π_{(u,v)∈E} 2√(du·dv)/(du+dv)

Edges with du+dv == 0 are skipped. Self-loops are skipped. Returns 1.0 for edgeless graphs.

For regular graphs, each factor is 1, so Πga = 1.

Examples

use rust_igraph::{Graph, multiplicative_ga};

// K_3: regular → each factor = 1 → product = 1
let g = Graph::from_edges(&[(0,1),(1,2),(0,2)], false, Some(3)).unwrap();
assert!((multiplicative_ga(&g).unwrap() - 1.0).abs() < 1e-10);