function createObject() {
  var request_type;
  var browser = navigator.appName;
  if(browser == "Microsoft Internet Explorer"){
    request_type = new ActiveXObject("Microsoft.XMLHTTP");
  }else{
    request_type = new XMLHttpRequest();
}
  return request_type;
}

var http = createObject();

function cal_mortgage() {
  r=Math.random();  
  p=document.getElementById('price').value;
  l=document.getElementById('loan').value;
  y=document.getElementById('year').value;
  i=document.getElementById('interest').value;
 
  http.open('get', 'cal_mortgage.php?p='+p+'&l='+l+'&y='+y+'&i='+i+'&r='+r);
  http.onreadystatechange = cal_mortgageReply;
  http.send(null);
}

function cal_mortgageReply() {  
  if(http.readyState==4){
    var response = http.responseText;
  	result=document.getElementById('result');       	  	
  	result.value=response;
  }
}