2.5. igraph_automorphisms — Number of automorphisms using BLISS

2.5. `igraph_automorphisms` — Number of automorphisms using BLISS

int igraph_automorphisms(const igraph_t *graph,
			 igraph_bliss_sh_t sh, igraph_bliss_info_t *info);

The number of automorphisms of a graph is computed using BLISS. The result is returned as part of the info structure, in tag group_size. It is returned as a string, as it can be very high even for relatively small graphs. If the GNU MP library is used then this number is exact, otherwise a long double is used and it is only approximate. See also igraph_bliss_info_t.

Arguments:

`graph`:	The input graph, it is treated as undirected and the multiple edges are ignored.
`sh`:	The split heuristics to be used in BLISS. See `igraph_bliss_sh_t`.
`info`:	The result is stored here, in particular in the `group_size` tag of `info`.

Returns:

Error code.

Time complexity: exponential, in practice it is fast for many graphs.