function myRound(val) {
	val = val * 1;
	val = Math.round(val);
	return val / 1;
}
function calc_payment() {
var Price = 0;
Price = document.getElementById('calc_price').value;
var interest = document.getElementById('calc_rate').value;
var months = document.getElementById('calc_term').value;
var trade = document.getElementById('calc_trade').value;
trade = trade.replace(",", "");
trade = trade * 1;

Price = Price - (trade * 1);
if ((interest * 1) > 0){
	interest = (interest / 100.0) / 12;
} else { interest = 0; }

var pow = 1;
for (var j = 0; j < months; j++)
	pow = pow * (1 + interest);

if (interest > 0){
	var pmt = (Price * pow * interest) / (pow - 1);	
} else {
	var pmt = Price / months;
}
if (pmt > 0){
	document.getElementById('calc_amount').value = "$"+myRound(pmt);
} else {
	document.getElementById('calc_amount').value = "N/A";
	//alert("Sorry, the values you entered are not numbers!");	
}
}