text: function nFormatter(num, digits) {
      var si = [
        { value: 1, symbol: "" },
        { value: 1E3, symbol: "k" },
        { value: 1E6, symbol: "M" },
        { value: 1E9, symbol: "G" },
        { value: 1E12, symbol: "T" },
        { value: 1E15, symbol: "P" },
        { value: 1E18, symbol: "E" }
      ];
      var rx = /\.0+$|(\.[0-9]*[1-9])0+$/;
      var i;
      for (i = si.length - 1; i > 0; i--) {
        if (num >= si[i].value) {
          break;
        }
      }
      return (num / si[i].value).toFixed(digits).replace(rx, "$1") + si[i].symbol;
  }
  
  
  function mathSign(x) {
      return ((x > 0) - (x < 0)) || +x;
  }
  
  export default {
      nFormatter,
      mathSign
  };