function checkValue(val)
			{
				t = val.split(",");
				if (t.length>1) s = parseFloat(t[0] + "." + t[1].substr(0,2));
				else s = parseFloat(val);
				return s;
			}

			function checkNaN(o) {
				if (isNaN(o.value)) {
					o.value = o.getAttribute('correct_value');
				} else {
					o.setAttribute('correct_value', o.value); 
				}  
				return true;   
			}

			function checkElementValue(elementId)
			{
				element = document.getElementById(elementId);
				checkNaN(element);
				value = checkValue(element.value);
				if (value) {
					element.className = 'ok';
				} else {
					element.className = 'error';
				}
				return value;
			}

			function calcPayment()
			{
				var price      = Math.ceil(checkElementValue("formPayment_price"));
				//var prepayment = checkElementValue("formPayment_prepayment") / 100;
				var time       = checkElementValue("formPayment_time") * 12;
				var rate       = checkElementValue("formPayment_rate") / 100;
				var prepayment_sum;
				var remaining_price;
				var payment;

				//prepayment_sum = Math.round(price * prepayment * 100) / 100;
				//remaining_price = price - prepayment_sum;
				remaining_price = price;

				payment = Math.round((remaining_price * (rate / 12 / (1 - Math.pow(1 + rate / 12, -time)))) * 100) / 100;
				if (isNaN(payment)){// || isNaN(prepayment_sum)) {
					payment = '?';
	//				prepayment_sum = '?';
				}
				document.getElementById("formPayment_payment").value = payment;
		//		document.getElementById("formPayment_prepaymentSum").value = prepayment_sum;
			}