Function pow

d3-3.2.8/d3.js:6834–6836

(x)

      return (positive ? Math.log(x < 0 ? 0 : x) : -Math.log(x > 0 ? 0 : -x)) / Math.log(base);
    }
    function pow(x) {
      return positive ? Math.pow(base, x) : -Math.pow(base, -x);
    }
    function scale(x) {
      return linear(log(x));
    }