通过两个点的经纬度计算距离

从google maps的脚本里扒了段代码，没准啥时会用上。大家一块看看是怎么算的。

private const double EARTH_RADIUS = 6378.137;

private static double rad(double d)

{

   return d * Math.PI / 180.0;

}

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 = 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)));

   s = s * EARTH_RADIUS;

   s = Math.Round(s * 10000) / 10000;

   return s;

}
转自：http://panyee.cnblogs.com/archive/2006/07/04/442771.html

//************************************************//
#define EARTH_RADIUS 6378.137

 double rad(double d)

{

   return d * M_PI / 180.0;

}

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 = 2 * asin(sqrt(pow(sin(a/2),2) +

    cos(radLat1)*cos(radLat2)*pow(sin(b/2),2)));

   s = s * EARTH_RADIUS;

   s = round(s * 10000) / 10000;

   return s;

}