int check(const igraph_vector_t *v1, const igraph_vector_t *v2, int code) {
igraph_vector_t v;
long int i, n=igraph_vector_size(v1);
igraph_real_t m;
igraph_vector_copy(&v, v1);
igraph_vector_sub(&v, v2);
for (i=0; i<n; i++) {
VECTOR(v)[i] = fabs(VECTOR(v)[i]);
}
if ( (m=igraph_vector_max(&v)) > 0.01) {
printf("Difference: %g\n", m);
exit(code);
}
igraph_vector_destroy(&v);
return 0;
}
/* Fan-in/ Fan-out method
*/
igraph_t *ggen_generate_fifo(gsl_rng *r, unsigned long n, unsigned long od, unsigned long id)
{
igraph_t *g = NULL;
igraph_vector_t available_od;
igraph_vector_t out_degrees;
igraph_vector_t vertices;
igraph_vector_t choice;
igraph_vector_t edges;
unsigned long max;
unsigned long i,j,k;
unsigned long vcount = 1;
int err;
ggen_error_start_stack();
if(r == NULL)
GGEN_SET_ERRNO(GGEN_EINVAL);
if(id == 0 || od == 0 || od > n || id > n)
GGEN_SET_ERRNO(GGEN_EINVAL);
g = malloc(sizeof(igraph_t));
GGEN_CHECK_ALLOC(g);
GGEN_FINALLY3(free,g,1);
GGEN_CHECK_IGRAPH(igraph_empty(g,1,1));
GGEN_FINALLY3(igraph_destroy,g,1);
GGEN_CHECK_IGRAPH(igraph_vector_init(&available_od,n));
GGEN_FINALLY(igraph_vector_destroy,&available_od);
GGEN_CHECK_IGRAPH(igraph_vector_init(&out_degrees,n));
GGEN_FINALLY(igraph_vector_destroy,&out_degrees);
GGEN_CHECK_IGRAPH(igraph_vector_init(&vertices,n));
GGEN_FINALLY(igraph_vector_destroy,&vertices);
GGEN_CHECK_IGRAPH(igraph_vector_init(&choice,n));
GGEN_FINALLY(igraph_vector_destroy,&choice);
GGEN_CHECK_IGRAPH(igraph_vector_init(&edges,n*2));
GGEN_FINALLY(igraph_vector_destroy,&edges);
while(vcount < n)
{
// never trigger errors as it doesn't allocate or free memory
igraph_vector_resize(&available_od,vcount);
igraph_vector_resize(&out_degrees,vcount);
igraph_vector_resize(&vertices,vcount);
// compute the available out degree of each vertex
GGEN_CHECK_IGRAPH(igraph_degree(g,&out_degrees,igraph_vss_all(),IGRAPH_OUT,0));
// fill available with od and substract out_degrees
igraph_vector_fill(&available_od,od);
GGEN_CHECK_IGRAPH(igraph_vector_sub(&available_od,&out_degrees));
if(gsl_ran_bernoulli(r,0.5)) //Fan-out Step
{
// find max
max = igraph_vector_max(&available_od);
// register all vertices having max as outdegree
j = 0;
for (i = 0; i < vcount; i++)
if(VECTOR(available_od)[i] == max)
VECTOR(vertices)[j++] = i;
// choose randomly a vertex among availables
GGEN_CHECK_GSL_DO(i = gsl_rng_uniform_int(r,j));
// how many children ?
GGEN_CHECK_GSL_DO(j = gsl_rng_uniform_int(r,max));
j = j+1;
// create all new nodes and add edges
GGEN_CHECK_IGRAPH(igraph_add_vertices(g,j,NULL));
// cannot fail
igraph_vector_resize(&edges,j*2);
for(k = 0; k < j; k++)
{
VECTOR(edges)[2*k] = i;
VECTOR(edges)[2*k+1] = vcount + k;
}
vcount+=k;
}
else //Fan-In Step
{
// register all vertices having an available outdegree
j = 0;
for (i = 0; i < vcount; i++)
if(VECTOR(available_od)[i] > 0)
VECTOR(vertices)[j++] = i;
// we can add at most id vertices
max =( j > id)? id: j;
// how many edges to add
GGEN_CHECK_GSL_DO(k = gsl_rng_uniform_int(r,max));
k = k+1;
// choose that many nodes and add edges from them to the new node
// cannot fail either
igraph_vector_resize(&choice,k);
gsl_ran_choose(r,VECTOR(choice),k,
VECTOR(vertices),j,sizeof(VECTOR(vertices)[0]));
// add a vertex to the graph
GGEN_CHECK_IGRAPH(igraph_add_vertices(g,1,NULL));
igraph_vector_resize(&edges,k*2);
// be carefull, vcount is the last ID of vertices not vcount +1
for(i = 0; i < k; i++)
{
VECTOR(edges)[2*i] = VECTOR(choice)[i];
VECTOR(edges)[2*i+1] = vcount;
}
vcount++;
}
// in all cases, edges should be added
GGEN_CHECK_IGRAPH(igraph_add_edges(g,&edges,NULL));
}
ggen_error_clean(1);
return g;
ggen_error_label:
return NULL;
}
