Important: The networks package has been deprecated.  Use the superseding package GraphTheory instead.

This routine is used to recover the names of the vertices at the ends of a specified edge.

In the special case where only the graph G is specified then the ends of all of the edges of G are returned as a set.

If an edge e is directed then the ends are returned as a list of length 2 where the second element is the head.  For undirected edges the vertex names are returned as a set.  Undirected loops will appear as a set containing one vertex name.

Specific edges of interest may be specified either individually or as a set or list of edge names. The result will be a vertex pair, a set of vertex pairs, or a list of vertex pairs as appropriate.

This routine is normally loaded via the command with(networks) but may also be referenced using the full name networks[ends](...).