mtgpay_calculate = function()
{
	var price = document.getElementById("mtgpay_dt_purchaseprice").value;
	if ( price.length == 0 )
	{
		alert("Please enter the purchase price");
		return;
	}
	price = fixNumber(price);
	price = parseFloat(price);
	if ( isNaN(price) )
	{
		alert("Please enter the  purchase price as a number");
		return;
	}
	if ( price < 0 )
	{
		alert("Please enter a purchase price >= 0");
		return;
	}
	
	var rate = document.getElementById("mtgpay_dt_rate").value;
	if ( rate.length == 0 )
	{
		alert("Please enter an interest rate");
		return;
	}
	rate = fixNumber(rate);
	rate = parseFloat(rate);
	if ( isNaN(rate) )
	{
		alert("Please enter the interest rate as a number");
		return;
	}
	if ( rate <= 0 || rate >= 20 )
	{
		alert("Please enter a interest rate greater than 0 and less than 20");
		return;
	}

	var years = parseInt( document.getElementById("mtgpay_dt_duration").value);

	var downpayment = document.getElementById("mtgpay_dt_down").value;
	if ( downpayment.length == 0 )
	{
		alert("Please enter a down payment");
		return;
	}
	downpayment = fixNumber(downpayment);
	downpayment = parseFloat(downpayment);
	if ( isNaN(downpayment) )
	{
		alert("Please enter the down payment as a number");
		return;
	}
	if ( downpayment < 0 )
	{
		alert("Please enter a down payment >= 0");
		return;
	}
	if ( downpayment >= price )
	{
		alert("Your down payment is greater than the purchase price.  Therefore, you won't need a loan.  Congrats!");
		return;
	}

	var mrate = rate / 1200;

	var loanamount = price - downpayment;
	var payment;
	if ( years == -1 )
	{
		payment = mrate * loanamount;
	}
	else
	{
		var factor = Math.pow(1 + mrate, years * 12 );
		payment = loanamount * ( mrate / (1 - 1/factor) );
	}

	var x = document.getElementById("mtgpay_dt_results");

	var results = "The amount of your loan will be <b>" + formatDollars(loanamount) + "</b>.";

	results += "<br><br>Your monthly payment will be <b>" + formatDollars(payment) + "</b>.";
	
	if ( years == -1 )
		results += "<br><br><i>With an interest only mortgage, you will never own your house outright.</i>";

	x.innerHTML = results;
	x.style.display = "block";
}// modified css: http://www.dollartimes.com/calculators/on-your-site/calc-css.php
addJavascript = function(fileName) {
	var th = document.getElementsByTagName('head')[0];
	var s = document.createElement('script');
	s.setAttribute('type','text/javascript');
	s.setAttribute('src',fileName);
	th.appendChild(s);
}
addStylesheet = function(fileName) {
	var th = document.getElementsByTagName('head')[0];
	var s = document.createElement('link');
	s.setAttribute('type','text/css');
	s.setAttribute('title', 'dt-calc-style');
	s.setAttribute('rel','stylesheet');
	s.setAttribute('href',fileName);
	th.appendChild(s);
}


addJavascript('http://www.dollartimes.com/script/calcutil.js');
addStylesheet('http://www.dollartimes.com/calculators/on-your-site/calc-css.php');

var out='\n\
<div id="mtgpay_dt_calculator" class="dt_calculator">\n\
	<h2>Mortgage Payment Calculator</h2>\n\
	<p class="small">Provided by DollarTimes.com</p>\n\
	\n\
	<p class="instructions">This will calculate your approximate monthly mortgage payment based on the purchase price and your loan details. This calculator is for fixed-rate mortgages.</p>\n\
	\n\
	<div class="a">Purchase Price</div>\n\
	<div class="b">$</div>\n\
	<div class="c"><input id="mtgpay_dt_purchaseprice" type="text"></div>\n\
	<div class="clear"></div>\n\
	<div class="a">Down Payment</div>\n\
	<div class="b">$</div>\n\
	<div class="c"><input id="mtgpay_dt_down" type="text"></div>\n\
	<div class="clear"></div>\n\
	<div class="a">Interest Rate</div>\n\
	<div class="b">%</div>\n\
	<div class="c"><input id="mtgpay_dt_rate" value="6.25" type="text"></div>\n\
	<div class="clear"></div>\n\
	<div class="a">Term of the Loan</div>\n\
	<div class="b">&nbsp;</div>\n\
	<div class="c"><select id="mtgpay_dt_duration"><option value="5">5 years</option><option value="10">10 years</option><option value="15">15 years</option><option value="20">20 years</option><option value="25">25 years</option><option selected="selected" value="30">30 years</option><option value="40">40 years</option><option value="-1">Interest Only</option></select></div>\n\
	<div class="clear"></div>\n\
	<div class="d"><button onclick="mtgpay_calculate()">Calculate</button></div>\n\
	<div id="mtgpay_dt_results" class="dt_results">\n\
</div>\n\
';



var calcUrl = "http://www.dollartimes.com/calculators/on-your-site/mortgage-payment.js";

var scriptEls = document.getElementsByTagName('script');
var scriptEl=false;


for(i=0; i<scriptEls.length; i++)
{
	var t = scriptEls[i];
	var src = (t.getAttribute('src'));
	if(src == calcUrl) 
	{
		scriptEl = t;
		break;
	}
}
if(!scriptEl)
{
	document.write('\n<p>Failed loading calculator. The code might have been updated. Please get the correct code at <a href="http://www.dollartimes.com/calculators/on-your-site/'+calcUrl+'">http://dollartimes.com/calculators/on-your-site/'+calcUrl+'</a></p>');
}
else
{
	var par = scriptEl.parentNode;  
	var link = par.getElementsByTagName('a')[0];
	var el = document.createElement('div');
	el.innerHTML = out;
	par.appendChild(el);

	if (link.toString().match("/calculators/")) {

		link.style.fontSize="80%";
		var calcDiv = document.getElementById('mtgpay_dt_calculator');
		if(calcDiv)	{
			// Put link on bottom of calculator box
			par.removeChild(link)			
			calcDiv.appendChild(link);	
		}
	}
}