Scilab function

graph_simp - converts a graph to a simple undirected graph

### Calling Sequence

  `g1 = graph_simp(g)`

### Parameters

- `g` : graph list of the old graph
- `g1` : graph list of the new graph

### Description

`graph_simp` returns the simple undirected graph `g1` corresponding to multigraph `g`. It deletes loops in `g`, replaces directed edges with undirected edges and replaces multiple edges with single edges.

### Examples

    ta=[1 1  1 2 2 2 3 4 4 4 5 5 6 7 7 8 8 9 9 10 10 10 10 10 11 12 12 13 13 13 14 15 16 16 17 17];
    he=[1 2 10 3 5 7 4 2 9 9 4 6 6 8 2 6 9 7 4  7 11 13 13 15 12 11 13 9 10 14 11 16 1 17 14 15];
    g=make_graph('foo',1,17,ta,he);
    g('node_x')=[283 163  63  98 164 162 273 235 267 384 504 493 409 573 601 627 642];
    g('node_y')=[ 59 133 223 311 227 299 221 288 384 141 209 299 398 383 187 121 301];
    show_graph(g);
    g1=graph_simp(g);
    show_graph(g1,'new');