Object.extend(Number.prototype, {
  format: function(decimals, dec_point, thousands_sep) {
  var number = this;
  var exponent = '';
  var numberstr = number.toString();
  var eindex = numberstr.indexOf('e');

  if (eindex > -1) {
    exponent = numberstr.substring(eindex);
    number = parseFloat(numberstr.substring(0, eindex));
  }
  
  if (decimals != null) {
    var temp = Math.pow(10, decimals);
    number = Math.round(number * temp) / temp;
  }

  var sign = number < 0 ? "-" : "";
  var integer = (number > 0 ? Math.floor(number) : Math.abs(Math.ceil(number))).toString();
  var fractional = number.toString ().substring (integer.length + sign.length);
  dec_point = dec_point != null ? dec_point : ".";
  fractional = decimals != null && decimals > 0 || fractional.length > 1 ? (dec_point + fractional.substring(1)) : '';
  if (decimals != null && decimals > 0)  {
    for (i = fractional.length - 1, z = decimals; i < z; ++i) {
      fractional += "0";
    }
  }
  
  thousands_sep = (thousands_sep != dec_point || fractional.length == 0) ? thousands_sep : null;
  if (thousands_sep != null && thousands_sep != '') {
    for (i = integer.length - 3; i > 0; i -= 3) {
      integer = integer.substring (0 , i) + thousands_sep + integer.substring(i);
    }
  }
  
  return sign + integer + fractional + exponent; 
  }
});