用坐标计算里程

代码一

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.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; }

代码二

double hypot(double x, double y)
{  return sqrt(x * x + y * y); }

double distance(double wd1, double jd1, double wd2, double jd2)
{// 根据经纬度坐标计算实际距离
 double x, y, out;
  double PI = 3.1415926535898; 
  double R = 6.371229 * 1e6; 
  x = (jd2 - jd1) * PI * R * cos( ( (wd1 + wd2) / 2) * PI / 180) / 180;
   y = (wd2 - wd1) * PI * R / 180;
    out = hypot(x, y);
     return out; }

点A的经度为11695400，纬度为3995400。点B的经度为11695300，纬度为3995300。
公式:两点间距离 = [ (A点经度 - B点经度)^2 + (A点纬度 - B点纬度)^2 ] ^ (1/2) = [ (11695400 - 11695300)^2
+ (3995400 - 3995300)^2 ] ^(1/2) =(10000+10000) ^ (1/2) =141米