//check for valid input
function compareDeal() {
	var form = document.forms.raterebate;
	var repeat = form.elements.length - 2;
	for (var i = 0; i < repeat; i++) {
		// check that everthing is filled in
		noAnswer = 0;
		if (form[i].value == "") {
			alert("Please fill in all fields");
			form[i].focus();
			noAnswer = 1;
			i = repeat;
		} else {
			// check for numeric values where needed
			if (form[i].name != "moyears") {
				if (isNaN(form[i].value)) {
					alert("Please enter numbers only. Do not use '$', '%' or commas");
					form[i].focus();
					form[i].select();
					i = repeat;
				}
			}
		}
	}

	// Do the math
	//convert months to years
	termYears = form.term.value;
	if (form.moyears[1].checked) {
		termYears = termYears/12;
	}

	// get interest multiplier
	rebInt = form.rebint.value;
	if (rebInt >= .3) {
		rebInt = rebInt/100;
	}
	rebnoInt = form.rebnoint.value;
	if (rebnoInt >= .3) {
		rebnoInt = rebnoInt/100;
	}

	intDiff =  rebnoInt - rebInt;
	if (intDiff < 0) {
		intDiff = -intDiff;
	}

	calcAmt = form.loanamt.value/2;

	bestDeal = calcAmt * intDiff * termYears - form.rebamt.value;

	if (isNaN(bestDeal) || noAnswer == 1) {
		form.result.value = "";
	} else {
		// Give em the answer
		bestDeal = Math.round(bestDeal);
		if (bestDeal == 0) {
			bestDeal = "It's a wash";
		}
		if (bestDeal > 0) {
			bestDeal = "You would save $" + bestDeal + " by taking the lower interest rate.";
		}
		if (bestDeal < 0) {
			bestDeal = -bestDeal;
			bestDeal = "You would save $" + bestDeal + " by taking the rebate.";
		}		
		form.result.value = bestDeal;
	}
}