function IsNumeric(strString)
{
  var strValidChars = "0123456789,.-";
  var strChar;
  var blnResult = true;

  if (strString.length == 0) return false;

  for (i = 0; i < strString.length && blnResult == true; i++)
  {
    strChar = strString.charAt(i);
    if (strValidChars.indexOf(strChar) == -1)
    {
      blnResult = false;
    }
  }
  return blnResult;
}


function calculerCommission() {
  var prix_billet = document.calcul_commission.prix_billet.value;
  if (!IsNumeric(prix_billet))
    return;
  var commission;
  var resultat;
  prix_billet = prix_billet.replace(",",".");

  if (prix_billet == 0) {
    commission = 0;
  }
  else {
    if (prix_billet < 40 && prix_billet != 0) {
      commission = 0.99;
    }
    else {
      if ((prix_billet * 2.5 / 100) < 9.95) {
	commission = prix_billet * 2.5 / 100;
      }
      else {
	commission = 9.95;
      }
    }
  }

  resultat = prix_billet - commission;

  commission = commission.toFixed(2);
  resultat = resultat.toFixed(2);

  document.calcul_commission.resultat_commission.value = commission + " Euro(s)";
  document.calcul_commission.resultat_organisateur.value = resultat + " Euro(s)";
}