function calcul_panier() {

if (document.getElementById('souscription___nb_livre').value <= 0 || isNaN(document.getElementById('souscription___nb_livre').value)) {
	document.getElementById('souscription___tot_livre').value = "";
	document.getElementById('souscription___aff_tot_livre').value = "";
	document.getElementById('souscription___nb_livre').value = "";}
	
else {
	document.getElementById('souscription___tot_livre').value = 
		document.getElementById('souscription___p_livre').value * document.getElementById('souscription___nb_livre').value;
	document.getElementById('souscription___aff_tot_livre').value = document.getElementById('souscription___tot_livre').value + '.-';
	}

}