function Kalkulator(kurz_eur,kurz_usd) {
vlozeno = eval(kalkulator.czk.value);

vysledek_usd= vlozeno / kurz_usd;
vysledek_eur= vlozeno / kurz_eur;
document.getElementById("usd").innerHTML=formatCurrency(vysledek_usd);
document.getElementById("eur").innerHTML=formatCurrency(vysledek_eur);
}

function formatCurrency(num) {
  num = num.toString().replace(/\$|\,/g,'');
  if(isNaN(num))
    num = "0";
  sign = (num == (num = Math.abs(num)));
  num = Math.floor(num*100+0.50000000001);
  cents = num%100;
  num = Math.floor(num/100).toString();
  if(cents<10)
    cents = "0" + cents;
  for (var i = 0; i < Math.floor((num.length-(1+i))/3); i++)
    num = num.substring(0,num.length-(4*i+3))+' '+
  num.substring(num.length-(4*i+3));
  return (((sign)?'':'-') + num + ',' + cents);
}