code: function LatLon(lat, lon, rad) {
        if (typeof(rad) == 'undefined') rad = 6371;  // earth's mean radius in km
        // only accept numbers or valid numeric strings
        this._lat = typeof(lat)=='number' ? lat : typeof(lat)=='string' && lat.trim()!='' ? +lat : NaN;
        this._lon = typeof(lon)=='number' ? lon : typeof(lon)=='string' && lon.trim()!='' ? +lon : NaN;
        this._radius = typeof(rad)=='number' ? rad : typeof(rad)=='string' && trim(lon)!='' ? +rad : NaN;
      }
docs: Creates a point on the earth's surface at the supplied latitude / longitude
  
  @constructor
  @param {Number} lat: latitude in numeric degrees
  @param {Number} lon: longitude in numeric degrees
  @param {Number} [rad=6371]: radius of earth if different value is required from standard 6,371km