/**
* \ingroup interface
* \function igraph_empty_attrs
* \brief Creates an empty graph with some vertices, no edges and some graph attributes.
*
* </para><para>
* Use this instead of \ref igraph_empty() if you wish to add some graph
* attributes right after initialization. This function is currently
* not very interesting for the ordinary user, just supply 0 here or
* use \ref igraph_empty().
* \param graph Pointer to a not-yet initialized graph object.
* \param n The number of vertices in the graph, a non-negative
* integer number is expected.
* \param directed Whether the graph is directed or not.
* \param attr The attributes.
* \return Error code:
* \c IGRAPH_EINVAL: invalid number of vertices.
*
* Time complexity: O(|V|) for a graph with
* |V| vertices (and no edges).
*/
int igraph_empty_attrs(igraph_t *graph, igraph_integer_t n, igraph_bool_t directed, void* attr) {
if (n<0) {
IGRAPH_ERROR("cannot create empty graph with negative number of vertices",
IGRAPH_EINVAL);
}
if (!IGRAPH_FINITE(n)) {
IGRAPH_ERROR("number of vertices is not finite (NA, NaN or Inf)", IGRAPH_EINVAL);
}
graph->n=0;
graph->directed=directed;
IGRAPH_VECTOR_INIT_FINALLY(&graph->from, 0);
IGRAPH_VECTOR_INIT_FINALLY(&graph->to, 0);
IGRAPH_VECTOR_INIT_FINALLY(&graph->oi, 0);
IGRAPH_VECTOR_INIT_FINALLY(&graph->ii, 0);
IGRAPH_VECTOR_INIT_FINALLY(&graph->os, 1);
IGRAPH_VECTOR_INIT_FINALLY(&graph->is, 1);
VECTOR(graph->os)[0]=0;
VECTOR(graph->is)[0]=0;
/* init attributes */
graph->attr=0;
IGRAPH_CHECK(igraph_i_attribute_init(graph, attr));
/* add the vertices */
IGRAPH_CHECK(igraph_add_vertices(graph, n, 0));
IGRAPH_FINALLY_CLEAN(6);
return 0;
}
igraph_real_t igraph_biguint_get(igraph_biguint_t *b) {
long int size=igraph_biguint_size(b);
long int i;
double val=VECTOR(b->v)[size-1];
if (size==0) { return 0.0; }
for (i=size-2; i>=0; i--) {
val = val * LIMBMASK + VECTOR(b->v)[i];
if (!IGRAPH_FINITE(val)) break;
}
return val;
}
