C#计算两个经纬度的距离
//地球半径，单位米private const double EARTH_RADIUS = 6378137;/// <summary>/// 计算两点位置的距离，返回两点的距离，单位 米/// 该公式为GOOGLE提供，误差小于0.2米/// </summary>/// <param name="lat1">第一点纬度</param>/// <param name="lng1">第一点经度</param>/// <param name="lat2">第二点纬度</param>/// <param name="lng2">第二点经度</param>/// <returns></returns>public static double GetDistance(double lat1, double lng1, double lat2, double lng2){double radLat1 = Rad(lat1);double radLng1 = Rad(lng1);double radLat2 = Rad(lat2);double radLng2 = Rad(lng2);double a = radLat1 - radLat2;double b = radLng1 - radLng2;double result = 2 * Math.Asin(Math.Sqrt(Math.Pow(Math.Sin(a / 2), 2) + Math.Cos(radLat1) * Math.Cos(radLat2) * Math.Pow(Math.Sin(b / 2), 2))) * EARTH_RADIUS;return result;}/// <summary>/// 经纬度转化成弧度/// </summary>/// <param name="d"></param>/// <returns></returns>private static double Rad(double d){return (double)d * Math.PI / 180d;}