PHP calculates the distance between two points of coordinates

Define (' PI ', 3.1415926535898);d efine (' Earth_radius ', 6378.137);//calculation range, can do search user function GetRange ($lat, $lon, $raidus)    {//calculate latitude $degree = (24901 * 1609)/360.0;     $dpmLat = 1/$degree;    $radiusLat = $dpmLat * $raidus; $minLat = $lat-$radiusLat; Get the minimum latitude $maxLat = $lat + $radiusLat;    Get maximum latitude//calculate Longitude $mpdLng = $degree * cos ($lat * (pi/180));    $dpmLng = 1/$mpdLng;    $radiusLng = $dpmLng * $raidus;  $minLng = $lon-$radiusLng;  Get the minimum longitude $maxLng = $lon + $radiusLng; Get the maximum longitude//Range $range = Array (' minlat ' = = $minLat, ' maxlat ' = $maxLat, ' minlon ' = $m    INLNG, ' maxlon ' = $maxLng); return $range;}    Get distance between 2 points function getdistance ($lat 1, $lng 1, $lat 2, $lng 2) {$radLat 1 = $lat 1 * (pi/180);       $radLat 2 = $lat 2 * (pi/180);     $a = $radLat 1-$radLat 2;        $b = ($lng 1 * (pi/180))-($lng 2 * (pi/180));     $s = 2 * ASIN (sqrt (Pow (sin ($a/2), 2) + cos ($radLat 1) *cos ($radLat 2) *pow (sin ($b/2), 2))); $s = $s * Earth_radius;     $s = round ($s * 10000)/10000; return $s; }

PHP calculates the distance between two points of coordinates