description of the main graph data structure
A graph in Scilab is represented by a Scilab typed list with type graph
and 5 fields:
version
a simple string which contains the graph data structure version identifier.
name
a simple string which contains the graph name.
directed
a number with possible values 0 and 1.
The value 1 means that the graph edges are oriented.
nodes
A Scilab mlist data structure,
which stores the information relative to nodes (see nodes_data_structure).
edges
A Scilab mlist data structure,
which stores the information relative to edges (see edges_data_structure).