// JavaScript Document
// Calculate the monthly principal and interest payment
// parameters:
//   Price: property sales price, in currency (i.e. 700000)
//   DownPymtPct = amount of down payment, in percent (i.e. 20)
//   IntRate = annual interest rate, in percent (i.e. 6.25)
//   LoanTerm = length of the loan, in years (i.e. 30)
// returns:  Payment, in currency (i.e. 345.67)
function floor(number) {
	return Math.floor(number*Math.pow(10,2))/Math.pow(10,2);
}
function calculate_payment() {
	var oPrice = document.getElementById("price");
	var oDownPymtPct = document.getElementById("down_pct");
	var oIntRate = document.getElementById("int_rate");
	var oLoanTerm = document.getElementById("loan_term");
	var oPayment = document.getElementById("fc_payment");
	//  
	var val = oPrice.value * ((100 - oDownPymtPct.value) / 100)
	var mi = oIntRate.value / 1200;
	var base = 1;
	var mbase = 1 + mi;
	var terms = oLoanTerm.value
	var end = ""
	for (i=0; i<(terms * 12); i++) {
		base = base * mbase
	}
	var Num = "" + floor(val * mi / ( 1 - (1/base)))
	if (Num.indexOf(".")>0) {
		arr = Num.split(".")
		if (arr[1].length==1) end = "0"
	}	else {
		end = ".00"
	}
	Num = Num + end
	oPayment.innerHTML = Num
} // end function