通过两个GPS计算两个GPS点的距离

public static double GetDistance(double lat1, double lng1, double lat2, double lng2)

{

   double radLat1 = rad(lat1);

   double radLat2 = rad(lat2);

   double a = radLat1 - radLat2;

   double b = rad(lng1) - rad(lng2);

   double s =  * Math.Asin(Math.Sqrt(Math.Pow(Math.Sin(a/),) +

    Math.Cos(radLat1)*Math.Cos(radLat2)*Math.Pow(Math.Sin(b/),)));

   s = s * EARTH_RADIUS;

   s = Math.Round(s * ) / ;

   return s;

}

        private static double rad(double d)

        {

            return d * Math.PI / 180.0;

        }

        private const double EARTH_RADIUS = 6378.137;