function previous_next_photo(path_photos, nom_diapo, nb_photos, language, previous) {
	tmp = eval("document." + nom_diapo);
//alert("toto");
	if((tmp.ind_this_photo==null)) {
		tmp.ind_this_photo = (previous==true ? nb_photos : 2);
	} else {
		tmp.ind_this_photo = (previous==true ? (tmp.ind_this_photo-1) : (tmp.ind_this_photo + 1));
	}
//alert(tmp.ind_this_photo);
	if(tmp.ind_this_photo > nb_photos) {
		tmp.ind_this_photo = 1;
	}
	if(tmp.ind_this_photo <= 0) {
		tmp.ind_this_photo = nb_photos;
	}
	tmp.src = path_photos + nom_diapo + "_" + tmp.ind_this_photo + (language!="" ? ("_" + language) : "") + ".jpg";
}
// changes to next photo and programs the next change (setTimeout) by calling itself recursively.
function automaticNext(path_photos, nom_diapo, nb_photos, language, delay_ms) {
	previous_next_photo(path_photos,nom_diapo,nb_photos,language);
	cmdstr = "automaticNext('" + path_photos + "','" + nom_diapo + "'," + nb_photos + ",'" + language + "'," + delay_ms + ")";
	window.setTimeout(cmdstr, delay_ms);
}