function roundAmount(theDecimal) {
	var s = "" + Math.round(theDecimal * 100) / 100
	var i = s.indexOf('.');
	if (i < 0) {
		return s + ".00";
	}
	var t = s.substring(0, i + 1) + s.substring(i + 1, i + 3);
	if (i + 2 == s.length) {
		t += "0";
	}
	return t;
}

function calcEnergy() {
	if (document.getElementById("hours").value > 24){
		alert("24 hours a day is all we have!");
		return false;
	}
	
	document.getElementById("tariff").innerHTML = document.calc.energycost.value;
	document.getElementById("watts-energy-saving").innerHTML = document.calc.watt.value / 5;
	document.getElementById("annualcurrent").innerHTML = document.calc.watt.value;
	
	var yearlynormallamp = (document.calc.energycost.value * 0.01 * 365 * document.calc.use.value * document.calc.hours.value * document.calc.watt.value) / 1000;
	var yearlyenergysaving = (document.calc.energycost.value * 0.01 * 365 * document.calc.use.value * document.calc.hours.value * ((document.calc.watt.value)/5)) / 1000;
	var lifeenergysaving = ((((document.calc.watt.value * 0.001) - (document.calc.watt.value * 0.001 /5)) * 8000) * document.calc.energycost.value /100) * document.calc.use.value;
	
	document.getElementById("yearlynormallamp").innerHTML = roundAmount(yearlynormallamp,2);
	document.getElementById("yearlyenergysaving").innerHTML = roundAmount(yearlyenergysaving,2);
	document.getElementById("lifeenergysaving").innerHTML = roundAmount(lifeenergysaving,2);
	document.getElementById("total").innerHTML = roundAmount(yearlynormallamp-yearlyenergysaving,2);
}