void draw_automaton(Automaton* a){
  int state, arc;
  FILE *fic;
  int local_xfig = 0; /* mettre à 1 pour utiliser la version de xdot locale */
  
  if(a == NULL) return;

  fic = fopen(".tmp", "w");
  if (fic == NULL){
      fprintf(stderr, "impossible d'ouvrir le fichier .tmp\n");
      return;
  }

  fprintf(fic, "digraph fsm {\n");
  fprintf(fic, "graph [margin=\"0,0\"];\n");
  fprintf(fic, "node [shape = circle];\n");
  fprintf(fic, "rankdir=LR;\n");

  for(state = 0; state < a->num_states; state++) 
    for(arc = 0; arc < a->states[state].num_arcs; arc++)
      fprintf(fic, "%d -> %d [label=\"%d\"];\n", state, a->states[state].arcs[arc].destination, a->states[state].arcs[arc].symbol) ;
  

  for(state = 0; state < a->num_states; state++)
    if(a->states[state].is_final == TRUE)
      if (state == a->initial_state)
	fprintf(fic, "%d [shape=doublecircle style=bold];\n", state);
      else
	fprintf(fic, "%d [shape=doublecircle style=solid];\n", state);

  if(a->states[a->initial_state].is_final == FALSE)
    fprintf(fic, "%d [shape=circle style=bold];\n", a->initial_state);

  fprintf(fic, "}\n");
  if(fic != stdout)
      fclose(fic);
  
  if(local_xfig)
    system("./xdot .tmp &");
  else
    system("dot .tmp | xdot - &");
}