int main() {
igraph_t g;
igraph_integer_t result;
igraph_integer_t from, to;
igraph_vector_t path;
igraph_rng_t rng;
igraph_rng_init(&rng, &igraph_rngtype_mt19937);
igraph_barabasi_game(&g, 30, /*power=*/ 1, 30, 0, 0, /*A=*/ 1,
IGRAPH_DIRECTED, IGRAPH_BARABASI_BAG,
/*start_from=*/ 0, &rng);
igraph_diameter(&g, &result, 0, 0, 0, IGRAPH_UNDIRECTED, 1);
/* printf("Diameter: %li\n", (long int) result); */
igraph_destroy(&g);
igraph_ring(&g, 10, IGRAPH_DIRECTED, 0, 0);
igraph_vector_init(&path, 0);
igraph_diameter(&g, &result, &from, &to, &path, IGRAPH_DIRECTED, 1);
printf("diameter: %li, from %li to %li\n", (long int) result,
(long int) from, (long int) to);
print_vector(&path);
igraph_vector_destroy(&path);
igraph_destroy(&g);
igraph_rng_destroy(&rng);
return 0;
}
int main(void)
{
igraph_integer_t diameter;
igraph_t graph;
igraph_rng_seed(igraph_rng_default(), 42);
igraph_erdos_renyi_game(&graph, IGRAPH_ERDOS_RENYI_GNP, 1000, 5.0/1000, IGRAPH_UNDIRECTED, IGRAPH_NO_LOOPS);
igraph_diameter(&graph, &diameter, 0, 0, 0, IGRAPH_UNDIRECTED, 1);
printf("Diameter of a random graph with average degree 5: %d\n", (int) diameter);
igraph_destroy(&graph);
return 0;
}
int check_simple() {
igraph_t g;
long int nodes=100;
long int edges=1000;
igraph_real_t p=3.0/nodes;
long int runs=10;
long int r, e, ecount;
igraph_vector_t eids, pairs, path;
srand(time(0));
igraph_vector_init(&pairs, edges*2);
igraph_vector_init(&path, 0);
igraph_vector_init(&eids, 0);
for (r=0; r<runs; r++) {
igraph_erdos_renyi_game(&g, IGRAPH_ERDOS_RENYI_GNP, nodes, p,
/*directed=*/ 0, /*loops=*/ 0);
ecount=igraph_ecount(&g);
for (e=0; e<edges; e++) {
long int edge=RNG_INTEGER(0, ecount-1);
VECTOR(pairs)[2*e] = IGRAPH_FROM(&g, edge);
VECTOR(pairs)[2*e+1] = IGRAPH_TO(&g, edge);
}
igraph_get_eids(&g, &eids, &pairs, /*path=*/ 0, 0, /*error=*/ 1);
for (e=0; e<edges; e++) {
long int edge=VECTOR(eids)[e];
long int from1=VECTOR(pairs)[2*e];
long int to1=VECTOR(pairs)[2*e+1];
long int from2=IGRAPH_FROM(&g, edge);
long int to2=IGRAPH_TO(&g, edge);
long int min1= from1 < to1 ? from1 : to1;
long int max1= from1 < to1 ? to1 : from1;
long int min2= from2 < to2 ? from2 : to2;
long int max2= from2 < to2 ? to2 : from2;
if (min1 != min2 || max1 != max2) {
return 11;
}
}
igraph_diameter(&g, /*res=*/ 0, /*from=*/ 0, /*to=*/ 0, &path,
IGRAPH_UNDIRECTED, /*unconn=*/ 1);
igraph_get_eids(&g, &eids, /*pairs=*/ 0, &path, 0, /*error=*/ 1);
for (e=0; e<igraph_vector_size(&path)-1; e++) {
long int edge=VECTOR(eids)[e];
long int from1=VECTOR(path)[e];
long int to1=VECTOR(path)[e+1];
long int from2=IGRAPH_FROM(&g, edge);
long int to2=IGRAPH_TO(&g, edge);
long int min1= from1 < to1 ? from1 : to1;
long int max1= from1 < to1 ? to1 : from1;
long int min2= from2 < to2 ? from2 : to2;
long int max2= from2 < to2 ? to2 : from2;
if (min1 != min2 || max1 != max2) {
return 12;
}
}
igraph_destroy(&g);
}
igraph_vector_destroy(&path);
igraph_vector_destroy(&pairs);
igraph_vector_destroy(&eids);
return 0;
}
