Function sir 

pub fn sir(
    graph: &Graph,
    beta: f64,
    gamma: f64,
    no_sim: usize,
    seed: u64,
) -> IgraphResult<Vec<Sir>>

Runs no_sim independent SIR epidemic simulations on graph.

Edge directions are ignored: an edge contributes to both endpoints’ neighbourhoods. The graph must be simple in its undirected view (no self-loops, no parallel or mutual edges).

• beta — per-edge infection rate (rate for a susceptible with one infected neighbour); the rate scales linearly with the number of infected neighbours. Must be non-negative.
• gamma — recovery rate of an infected individual. Must be strictly positive (otherwise the process would never terminate).
• no_sim — number of independent runs. Must be positive.
• seed — seed for the deterministic SplitMix64 PRNG.

Returns one Sir trajectory per simulation.

Errors

• The graph is empty (vcount == 0).
• beta < 0, gamma <= 0, or no_sim == 0.
• The graph is not simple in its undirected view.

Examples

use rust_igraph::{Graph, sir};

// A small ring; every run starts with exactly one infected vertex.
let mut g = Graph::with_vertices(5);
g.add_edge(0, 1).unwrap();
g.add_edge(1, 2).unwrap();
g.add_edge(2, 3).unwrap();
g.add_edge(3, 4).unwrap();
g.add_edge(4, 0).unwrap();

let runs = sir(&g, 2.0, 1.0, 3, 0x5152).unwrap();
assert_eq!(runs.len(), 3);
for run in &runs {
    // Every trajectory starts at t = 0 with one infected, four susceptible.
    assert_eq!(run.times[0], 0.0);
    assert_eq!(run.no_i[0], 1);
    assert_eq!(run.no_s[0], 4);
    assert_eq!(run.no_r[0], 0);
    // Population is conserved at every step and ends with no infected.
    for k in 0..run.times.len() {
        assert_eq!(run.no_s[k] + run.no_i[k] + run.no_r[k], 5);
    }
    assert_eq!(*run.no_i.last().unwrap(), 0);
}