adj = xbt_graph_get_length_matrix(graph);
buf = xbt_new0(char, n * 20);
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
sprintf(buf + strlen(buf), "%le\t", adj[i * n + j]);
}
adj = xbt_graph_get_length_matrix(graph);
buf = xbt_new0(char, n * 20);
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
sprintf(buf + strlen(buf), "%le\t", adj[i * n + j]);
}