predecessors - tail nodes of incoming arcs of a node
predecessors returns the row vector of the numbers of the tail nodes of the incoming arcs to node i for a directed graph g .
ta=[1 6 2 4 7 5 6 8 4 3 5 1];
he=[2 1 3 6 4 8 8 7 2 7 3 5];
g=make_graph('foo',1,8,ta,he);
g('node_x')=[285 284 335 160 405 189 118 45];
g('node_y')=[266 179 83 176 368 252 64 309];
show_graph(g);
a=predecessors(8,g)
show_nodes(a);