function calc() {
var dext = document.forms[0].dext.value * 1;
var bonustoa = document.forms[0].bonustoa.value * 1;
var vitorigine = document.forms[0].vitorigine.value * 1;

if (dext < 60)
  {vitesse_dext = vitorigine;}

if (dext >= 60 && dext < 250)
  {vitesse_dext = vitorigine * (1 - ((dext-50)/10 - 1) * 0.015);}

if (dext >= 250)
  {vitesse_dext = vitorigine * (0.715 - ((dext-240)/10 - 1) * 0.02);}

var vitesse_incant = vitesse_dext * (1 - bonustoa/100);
var vitesse_incant = Math.round(vitesse_incant*1000)/1000;
var vitesse_div = document.getElementById("vitesse");
var cap_div = document.getElementById("cap");

vitesse_div.innerHTML = vitesse_incant;
cap_div.innerHTML = Math.round(vitorigine * 40)/100;
}