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);
}


function floor(number)
{
  return formatCurrency(Math.floor(number*Math.pow(10,2))/Math.pow(10,2));
}

function getValue(s)
{
	var z = s.length;
	var c = '';
	var oks = '.0123456789';
	var n  ='';
	for (var i = 0; i < z; i++)
	{
		c = s.charAt(i);
		if (oks.indexOf(c) > -1) n += c;
	}
	return n;
}

function dosum(f)
{
	var irv = getValue(f.IR.value);
	var aiv = getValue(f.AI.value);
	var atv = getValue(f.AT.value);
	var lav = getValue(f.LA.value) - getValue(f.DP.value);
  var mi = irv / 1200;
  var base = 1;
  var mbase = 1 + mi;
  for (i=0; i<f.YR.value * 12; i++)
  {
    base = base * mbase
  }
  f.PI.value = floor(lav * mi / ( 1 - (1/base)));
  f.MT.value = floor(atv / 12);
  f.MI.value = floor(aiv / 12);
  var dasum = lav * mi / ( 1 - (1/base)) +  atv / 12 +  aiv / 12;
  f.MP.value = floor(dasum);
}

dosum();