Function d3_formatPrefix

explainshell/web/static/js/d3.v3.js:1871–1881

(d, i)

    return d3_formatPrefixes[8 + i / 3];
  };
  function d3_formatPrefix(d, i) {
    var k = Math.pow(10, Math.abs(8 - i) * 3);
    return {
      scale: i > 8 ? function(d) {
        return d / k;
      } : function(d) {
        return d * k;
      },
      symbol: d
    };
  }
  d3.round = function(x, n) {
    return n ? Math.round(x * (n = Math.pow(10, n))) / n : Math.round(x);
  };