function toCurrency(num) {
    num = num.toString().replace(/\$|\,/g, '');
    if (isNaN(num)) num = '0';
    sign = (num == (num = Math.abs(num)));
    num = Math.floor(num * 100 + 0.50000000001);
    cents = num % 100;
    num = Math.floor(num / 100).toString();
    if (cents < 10) cents = '0' + cents;
    for (var i = 0; i < Math.floor((num.length - (1 + i)) / 3); i++)
        num = num.substring(0, num.length - (4 * i + 3)) + ',' + num.substring(num.length - (4 * i + 3));
    return (((sign) ? '' : '-') + '$' + num + '.' + cents);
}

function toNumber(num) {
    num = num.toString().replace(/\$|\,/g, '');
    if (isNaN(num)) num = '0';
    sign = (num == (num = Math.abs(num)));
    num = Math.floor(num).toString()
    for (var i = 0; i < Math.floor((num.length - (1 + i)) / 3); i++)
        num = num.substring(0, num.length - (4 * i + 3)) + ',' + num.substring(num.length - (4 * i + 3));
    return (((sign) ? '' : '-') + num);
}

function isNumber(n) {
    return !isNaN(parseFloat(n)) && isFinite(n);
}