Function modular_product 

pub fn modular_product(g1: &Graph, g2: &Graph) -> IgraphResult<Graph>

Computes the modular product of two graphs.

The result has |V1| * |V2| vertices. Vertex (i, j) is identified by i * |V2| + j. An edge exists between (i1, j1) and (i2, j2) iff:

• (i1, i2) is an edge in g1 AND (j1, j2) is an edge in g2, OR
• (i1, i2) is NOT an edge in g1 AND (j1, j2) is NOT an edge in g2 (with i1 ≠ i2 and j1 ≠ j2).

Both graphs must be simple (no self-loops, no multi-edges) and have the same directedness.

Computed as tensor(g1, g2) ∪ tensor(complement(g1), complement(g2)).

Arguments

• g1 — the first factor graph.
• g2 — the second factor graph.

Errors

Returns InvalidArgument if:

• the graphs differ in directedness,
• either graph is not simple,
• the product vertex count overflows u32.

Examples

use rust_igraph::{Graph, modular_product};

// P3 modular P3: modular product of two paths on 3 vertices
let mut g1 = Graph::with_vertices(3);
g1.add_edge(0, 1).unwrap();
g1.add_edge(1, 2).unwrap();
let mut g2 = Graph::with_vertices(3);
g2.add_edge(0, 1).unwrap();
g2.add_edge(1, 2).unwrap();

let p = modular_product(&g1, &g2).unwrap();
assert_eq!(p.vcount(), 9);