Google Maps calculates the two-point distance function based on the longitude and latitude.

Latitude

Longpolling longitude

Calculate the two-point distance function based on the longitude and latitude in the Google Maps script.

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;
}