function calculator(form) {
	if (form.price.value == 0 || form.price.value.length == 0 || GetValue(form.price.value)=="") {
		alert ("Please enter a Purchase Price");
		form.price.focus();

	}	else if (form.interest_rate.value == 0 || form.interest_rate.value.length == 0) {
		alert ("Please enter a valid interest rate");
		form.interest_rate.focus();

	} else {
		calculateRepayment(form);
	}

	return false;
}

function GetValue(str) {
	return Number(str.toString().replace(/[^0-9\.]/gi, ''));
}

function calculateRepayment(form) {
	// Get Values
	var principle = parseFloat(GetValue(form.price.value) - GetValue(form.deposit.value) - GetValue(form.tradein.value)) + 250;
	var payments_per_year = 52; // Weekly
	var total_num_payments = form.term.value * payments_per_year;
	var interest_rate = (form.interest_rate.value / (100 * payments_per_year));

	// Calculate
	var fv = parseFloat(-(principle / 100));
	var x = Math.pow(1 + interest_rate, total_num_payments);
	var monthly_repayments = Math.floor(((interest_rate * (fv + x * principle)) / (-1 + x)) * 100) / 100;

	// Output Values
	form.monthly_repayments.value = '$' + monthly_repayments.toFixed(2);
	// var priceAdd = GetValue(form.price.value);
	// var priceTop = parseFloat(priceAdd) + parseFloat(10000);
	// var priceBot = priceAdd - 10000;
}