function calculate()
{
    var ajaxObj = new Ajax.Request('/Tools/Calculators/VAT_Tax_Calculator',
            {method: 'post',
             parameters : 'amount='+ encodeURIComponent($('amount').value) +'&rate='+ encodeURIComponent($('rate').value) +'&exclude='+ ($('exclude_0').checked ? 0 : 1),
             onComplete: function(originalRequest)
            {
            	if (originalRequest.responseJSON && typeof originalRequest.responseJSON == 'object') {
            		$('txtVat').value = originalRequest.responseJSON.vat;
            		$('txtNet').value = originalRequest.responseJSON.net;
            	}
            }
    });

    ajaxObj = null;
    return false;
}

function calculatorReset() {
	['txtVat', 'txtNet'].each(function (field) {
		$(field).value = '';
	});
	
	$('rate').selectedIndex= 0;
	$('amount').value = '100.00';
	$('exclude_1').checked = true;
	
	return false;
}