Function grg_game 

pub fn grg_game(
    n: u32,
    radius: f64,
    torus: bool,
    seed: u64,
) -> IgraphResult<Graph>

Generate a geometric random graph on n uniformly placed points in the unit square, connecting pairs strictly closer than radius in Euclidean distance.

• n — vertex count. n = 0 returns an empty undirected graph; n = 1 returns a single isolated vertex.
• radius — Euclidean cut-off in the same units as the unit square. Negative values are coerced to 0 (matching upstream). The maximum meaningful value is sqrt(2) for the open square or sqrt(0.5) for the torus (above this every pair is in range).
• torus — periodic boundary conditions when true. The unit square is identified with a torus and y-distances wrap by 1 - |Δy| if shorter; x-wrapping is folded into the sweep tail.
• seed — seeds the internal SplitMix64 PRNG. Same (n, radius, torus, seed) always yields the same graph.

The generated graph is always undirected and free of self-loops (the sweep starts at j = i + 1). It is also simple — each pair (i, j) is inspected at most once, so no multi-edges arise.

Errors

Returns IgraphError::Internal if radius is NaN or infinite.

Examples

use rust_igraph::grg_game;

// Dense regime: radius near sqrt(2) connects almost every pair.
let dense = grg_game(20, 1.5, false, 0xA110).unwrap();
assert_eq!(dense.vcount(), 20);
assert!(dense.ecount() > 100);
assert!(!dense.is_directed());