function initKalkulator(calcOnInit) {
		var kalkulator = 	$('#kalkulator');
		var calc = 			$('#calcCredit');
		var credit = 		$('#credit');
		
		$('#price').change(function(){
			calculate();
		}).blur(function() {
			$(this).val(numberFormat($(this).val()));
		});
		$('#type').change(function(){
			calculate();
		});
		$('#duration').change(function(){
			calculate();
		});
		
				
		calc.click(function() {
			calculate();
		});
		
		if(calcOnInit) {
			$('#price').val(numberFormat($('#price').val()));
			calculate();
		}
		
		function calculate() {
			var price = 	$('#price').val();
			var type = 		$('#type').val();
			var duration = 	$('#duration').val();
			
			JSON_request({
				requestURL:	 	"ajax/books/calculate.credit.php",
				method: 		"POST",
				data:			"price="+price+"&type="+type+"&duration="+duration,
				callback:		handleCalc,
				errorCallback: 	handleCalcError
			});
			//$('#price').val(numberFormat($('#price').val()));
		}
		
		function handleCalc(data) {
			if(data.credit) {
				credit.empty().append(numberFormat(data.credit));
			}
			else {
				credit.empty().append("0");
			}
		}
		function handleCalcError() {
			
		}
		
		function numberFormat(number) {
			number = number + "";
			number = number.replace(",",".");
			if(number == "" || isNaN(number)) return 0;
			
			if(number == "")	return "";
			
			number = parseFloat(number);
			number = number.toFixed(2);
			number = number.replace(".",",");
			return number;
		}
	}