gas_calculate = function() {
	var miles = document.getElementById("gas_miles").value;
	if ( miles.length == 0 )
	{
		 alert("Please enter number of miles you drive each year");
		 return;
	}
	miles = fixNumber(miles);
	miles = parseFloat(miles);
	if ( isNaN(miles) )
	{
		 alert("Please enter number of miles you drive each year as a number");
		 return;
	}
	if ( miles <= 0 )
	{
		 alert("You aren't driving any miles, so you won't be spending anything on gas");
		 return;
	}

	var mpgold = document.getElementById("gas_mpgold").value;
	if ( mpgold.length == 0 )
	{
		 alert("Please enter the MPG of your current vehicle.");
		 return;
	}
	mpgold = fixNumber(mpgold);
	mpgold = parseFloat(mpgold);
	if ( isNaN(mpgold) )
	{
		 alert("Please enter the MPG of your current vehicle as a number.");
		 return;
	}
	if ( mpgold <= 0 )
	{
		alert("Your current vehicle gets 0 mpg, so it can't be driven.")
		return;
	}

	var mpgnew = document.getElementById("gas_mpgnew").value;
	if ( mpgnew.length == 0 )
	{
		 alert("Please enter the MPG of a new vehicle.");
		 return;
	}
	mpgnew = fixNumber(mpgnew);
	mpgnew = parseFloat(mpgnew);
	if ( isNaN(mpgnew) )
	{
		 alert("Please enter the MPG of a new vehicle as a number.");
		 return;
	}
	if ( mpgnew <= 0 )
	{
		alert("Your new vehicle gets 0 mpg, so it can't be driven.")
		return;
	}

	var cost = document.getElementById("gas_cost").value;
	if ( cost.length == 0 )
	{
		 alert("Please enter the cost of a gallon of gas");
		 return;
	}
	cost = fixNumber(cost);
	cost = parseFloat(cost);
	if ( isNaN(cost) )
	{
		 alert("Please enter the cost of a gallon of gas as a number");
		 return;
	}
	if ( cost <= 0 )
	{
		 alert("If gas is free, you won't save anything by being more fuel-efficient.");
		 return;
	}


	var costold = ( miles / mpgold ) * cost;
	var costnew = ( miles / mpgnew ) * cost;

	var results = "Gas for your current vehicle costs " + formatDollars(costold) + " dollars a year.";
	results += "<p>Gas for the new vehicle will cost " + formatDollars(costnew) + " dollars a year.";

	var savings = costold - costnew;
	if ( savings >= 0 )
		results += "<p>You will save " + formatDollars(savings) + " a year on gas.";
	else
		results += "<p>You will pay " + formatDollars(-1*savings) + " extra a year on gas.";

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


	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 = '\
<div id="gas_dt_calculator" class="dt_calculator">\n\
	<h2>Gas Savings Calculator</h2>\n\
	<p class="small">Provided by DollarTimes.com</p>\n\
	<p class="instructions">How much can you save with a more fuel efficient car?</p>\n\
	<div class="a">Miles Driven Per Year</div>\n\
	<div class="b"></div>\n\
	<div class="c"><input id="gas_miles" type="text" value="13,000" /></div>\n\
	<div class="clear"></div>\n\
	\n\
	\n\
	<div class="a">Current Miles per Gallon</div>\n\
	<div class="b"></div>\n\
	<div class="c"><input id="gas_mpgold" type="text" value="20" /></div>\n\
	<div class="clear"></div>\n\
	\n\
	<div class="a">Miles per Gallon of New Car</div>\n\
	<div class="b"></div>\n\
	<div class="c"><input id="gas_mpgnew" type="text" value="40" /></div>\n\
	<div class="clear"></div>\n\
	\n\
	<div class="a">Cost of Gas per Gallon</div>\n\
	<div class="b"></div>\n\
	<div class="c"><input id="gas_cost" type="text" value="3.25" /></div>\n\
	<div class="clear"></div>\n\
	\n\
	<div class="d"><div class="dt_button" onclick="gas_calculate()" onMouseover="this.className=\'dt_button_sel\'" onMouseout="this.className=\'dt_button_out\'">Calculate</div></div>\n\
	<div id="gas_dt_results" class="dt_results padded-table">&nbsp;</div>\n\
</div>\n\
';



var calcUrl = "http://www.dollartimes.com/calculators/on-your-site/gas-savings-calculator.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('gas_dt_calculator');
		if(calcDiv)	{
			// Put link on bottom of calculator box
			par.removeChild(link)			
			calcDiv.appendChild(link);	
		}
	}
}