d3.max = function(array, f) {
  var i = -1,
      n = array.length,
      a,
      b;
  if (arguments.length === 1) {
    while (++i < n && ((a = array[i]) == null || a != a)) a = undefined;
    while (++i < n) if ((b = array[i]) != null && b > a) a = b;
  } else {
    while (++i < n && ((a = f.call(array, array[i], i)) == null || a != a)) a = undefined;
    while (++i < n) if ((b = f.call(array, array[i], i)) != null && b > a) a = b;
  }
  return a;
};