d3.scale.log = function() {

  return d3_scale_log(d3.scale.linear(), d3_scale_logp);

};

function d3_scale_log(linear, log) {

  var pow = log.pow;

  function scale(x) {

    return linear(log(x));

  }

  scale.invert = function(x) {

    return pow(linear.invert(x));

  };

  scale.domain = function(x) {

    if (!arguments.length) return linear.domain().map(pow);

    log = x[0] < 0 ? d3_scale_logn : d3_scale_logp;

    pow = log.pow;

    linear.domain(x.map(log));

    return scale;

  };

  scale.nice = function() {

    linear.domain(d3_scale_nice(linear.domain(), d3_scale_niceDefault));

    return scale;

  };

  scale.ticks = function() {

    var extent = d3_scaleExtent(linear.domain()),

        ticks = [];

    if (extent.every(isFinite)) {

      var i = Math.floor(extent[0]),

          j = Math.ceil(extent[1]),

          u = Math.round(pow(extent[0])),

          v = Math.round(pow(extent[1]));

      if (log === d3_scale_logn) {

        ticks.push(pow(i));

        for (; i++ < j;) for (var k = 9; k > 0; k--) ticks.push(pow(i) * k);

      } else {

        for (; i < j; i++) for (var k = 1; k < 10; k++) ticks.push(pow(i) * k);

        ticks.push(pow(i));

      }

      for (i = 0; ticks[i] < u; i++) {} // strip small values

      for (j = ticks.length; ticks[j - 1] > v; j--) {} // strip big values

      ticks = ticks.slice(i, j);

    }

    return ticks;

  };

  scale.tickFormat = function(n, format) {

    if (arguments.length < 2) format = d3_scale_logFormat;

    if (arguments.length < 1) return format;

    var k = n / scale.ticks().length,

        f = log === d3_scale_logn ? (e = -1e-15, Math.floor) : (e = 1e-15, Math.ceil),

        e;

    return function(d) {

      return d / pow(f(log(d) + e)) < k ? format(d) : "";

    };

  };

  scale.copy = function() {

    return d3_scale_log(linear.copy(), log);

  };

  return d3_scale_linearRebind(scale, linear);

};

var d3_scale_logFormat = d3.format("e");

function d3_scale_logp(x) {

  return Math.log(x) / Math.LN10;

}

function d3_scale_logn(x) {

  return -Math.log(-x) / Math.LN10;

}

d3_scale_logp.pow = function(x) {

  return Math.pow(10, x);

};

d3_scale_logn.pow = function(x) {

  return -Math.pow(10, -x);

};