function round(num, mp) {
          if (mp == null)
            mp = 2;

          mpm = Math.pow(10, mp);
          if (num < 0) {
            num = -num;
            sign = "-";
          } else {
            sign = "";
          }
          pomnum = num * mpm;
          pomnum = Math.ceil(pomnum - 0.5);
          j = -1;
          retstring = "";
          while  ((pomnum > 0) || (mp > 0)) {
            cyfra = (pomnum % 10);
            retstring = cyfra + retstring;
            pomnum = pomnum / 10;
            pomnum = Math.floor(pomnum);
            if (j >= 0) {
              j++;
              if (((j % 3) == 0) && pomnum)
                retstring = " " + retstring;
            } else {
              mp--;
              if (mp == 0) {
                retstring = "," + retstring;
                j = 0;
              }
            }
          }
          if (retstring != 0)
            return sign + retstring;
          else
            return retstring;
        }


function calculate() {
       var wplata = parseFloat(document.getElementById("kwota").value);
       var rs = document.getElementById("stopa").value;
       var o = document.getElementById("okres").value;
  
    pattern=/^[0-9]+((\.|,)[0-9]+)?$/;
    document.kalkul.kwota.value = document.kalkul.kwota.value.replace(/,/,".");
    document.kalkul.stopa.value = document.kalkul.stopa.value.replace(/,/,".");
    document.kalkul.okres.value = document.kalkul.okres.value.replace(/,/,".");
    if ( document.kalkul.kwota.value>10000 || document.kalkul.kwota.value==0 || pattern.test(document.kalkul.kwota.value)==false)
        {
          document.getElementById("div02").style.display = "block";
          document.getElementById("div02").style.visibility = "visible";
        }   
    else {
        if (document.kalkul.stopa.value > 30 || document.kalkul.stopa.value==0 || pattern.test(document.kalkul.stopa.value)==false) {
          document.getElementById("div01").style.display = "block";
          document.getElementById("div01").style.visibility = "visible";
        }
        else {
          pattern = /^[0-9]+$/;
          if (document.kalkul.okres.value > 99 || document.kalkul.okres.value==0 || pattern.test(document.kalkul.okres.value)==false) {
          document.getElementById("div03").style.display = "block";
          document.getElementById("div03").style.visibility = "visible";
          }
          else {
            document.getElementById("div01").style.display = "none";
            document.getElementById("div01").style.visibility = "hidden";
            document.getElementById("div02").style.display = "none";
            document.getElementById("div02").style.visibility = "hidden";
            document.getElementById("div03").style.display = "none";
            document.getElementById("div03").style.visibility = "hidden";
            licz_kapital(wplata, rs, o);
          }
        }     
         }
    }

    function licz_kapital(wplata,rs,o)
  {
      var mw = wplata;     
      var rzs = rs / 100;
      var oi = o * 12;
      var odsetki = 0;    
      var kapital = 0;
            
      for ( i = 1; i <= oi; i++ )
      {   
          var kapital = mw + kapital + odsetki;     
      var odsetki = kapital * rzs / 12;         
        var na_koncie = kapital + odsetki;            
      }
      
      document.getElementById("sumawplat").value = round(oi * wplata);
      document.getElementById("zysk").value = round(na_koncie - (oi * wplata));
      document.getElementById("razem").value = round(na_koncie); 
  }