Php uses the longitude and latitude of two locations to determine the distance

Php uses the longitude and latitude of two locations to determine the distance /**
* Calculate the distance between two known longitude and latitude, in meters.
* @ Param lng1, lng2 longitude
* @ Param lat1, lat2 latitude
* @ Return float distance, in meters
* @ Author yalong sun
**/
Function getdistance ($ lng1, $ lat1, $ lng2, $ lat2 ){
// Convert the angle to the Fox
$ RadLat1 = deg 2rad ($ lat1); // The deg 2rad () function converts degrees to radians.
$ RadLat2 = deg 2rad ($ lat2 );
$ RadLng1 = deg 2rad ($ lng1 );
$ RadLng2 = deg 2rad ($ lng2 );
$ A = $ radLat1-$ radLat2;
$ B = $ radLng1-$ radLng2;
$ S = 2 * asin (sqrt (pow (sin ($ a/2), 2) + cos ($ radLat1) * cos ($ radLat2) * pow (sin ($ B/2), 2) x 6378.137*1000;
Return $ s;
}
Echo getdistance (116.46865, 39.914638, 116.482233, 39.91425 );
?>