function auto_complete(_ou){
    if($(_ou)){
	    new Ajax.Autocompleter(_ou, _ou+'_ac', 
	        'http://www.investir.fr/api/autocomplete_valeur.php', 
	        {
		    method: 'get'
	        } 
	    );
	}
}
Event.observe(window, "load", function(){auto_complete('search')});
Event.observe(window, "load", function(){auto_complete('search_bas')});