var optimizedLength;

(function(){
  function noop(){};
  var deg2rad = Math.PI / 180;
  
  var sum,
      lambda0,
      sinPhi0,
      cosPhi0;
  
  var length = {
    sphere: noop,
    point: function(lambda, phi) {
      lambda *= deg2rad, phi *= deg2rad;
      if(lambda0 === null) {
        lambda0 = lambda, sinPhi0 = Math.sin(phi), cosPhi0 = Math.cos(phi);
      } else {
        var sinPhi = Math.sin(phi),
            cosPhi = Math.cos(phi),
            delta = Math.abs(lambda - lambda0),
            cosDelta = Math.cos(delta),
            sinDelta = Math.sin(delta),
            t;
        sum += Math.atan2(
          Math.sqrt((t = cosPhi * sinDelta) * t + (t = cosPhi0 * sinPhi - sinPhi0 * cosPhi * cosDelta) * t),
          sinPhi0 * sinPhi + cosPhi0 * cosPhi * cosDelta
        );
        lambda0 = lambda, sinPhi0 = sinPhi, cosPhi0 = cosPhi;
      }
    },
    lineStart: function(){
      lambda0 = sinPhi0 = cosPhi0 = null;
    },
    lineEnd: function(){
      lambda0 = sinPhi0 = cosPhi0 = null;
    },
    polygonStart: noop,
    polygonEnd: noop
  };
  
  optimizedLength = function(object) {
    sum = 0;
    d3.geo.stream(object, length);
    return sum;
  }
})();