function calculate()
{
    var ajaxObj = new Ajax.Request('/Tools/Calculators/VAT_Calculator',
            {method: 'post',
             parameters : 'start='+ encodeURIComponent($('start').value) +'&vat='+ ($('vat_0').checked ? 0 : 1)+'&rate=23',
             onComplete: function(originalRequest)
            {
            	if (originalRequest.responseJSON && typeof originalRequest.responseJSON == 'object') {
            		$('txtTax').value = originalRequest.responseJSON.tax;
            		$('txtNet').value = originalRequest.responseJSON.vat;
            		$('txtGross').value = originalRequest.responseJSON.gross;
            	}
            }
    });

    ajaxObj = null;
    return false;
}

function calculatorReset() {
	['txtGross', 'txtNet', 'txtTax'].each(function (field) {
		$(field).value = '';
	});
	
	$('start').value = '100.00';
	$('vat_0').checked = true;
	
	return false;
}