PHP to calculate the distance between the coordinates of the Baidu map _php tips

This article describes the PHP to achieve the calculation of Baidu map coordinates the distance between the method. Share to everyone for your reference, specific as follows:

The following is the code on the Web, you need to make some changes when you use it

The first function is to obtain the range, the parameter is the latitude longitude radius

The second function is to compute the coordinate distance

<?php define (' PI ', 3.1415926535898);
Define (' Earth_radius ', 6378.137);
  The range of calculations can be done by searching user function GetRange ($lat, $lon, $raidus) {//computed latitude $degree = (24901 * 1609)/360.0;
  $dpmLat = 1/$degree;
  $radiusLat = $dpmLat * $raidus; $minLat = $lat-$radiusLat; Get the minimum latitude $maxLat = $lat + $radiusLat;
  The maximum latitude/longitude is computed $mpdLng = $degree * cos ($lat * (pi/180));
  $dpmLng = 1/$mpdLng;
  $radiusLng = $dpmLng * $raidus; $minLng = $lon-$radiusLng; To obtain the minimum longitude $maxLng = $lon + $radiusLng;
    Get maximum longitude/range $range = Array (' Minlat ' => $minLat, ' Maxlat ' => $maxLat, ' Minlon ' => $minLng,
  ' Maxlon ' => $maxLng);
return $range;
  //Get Distance function getdistance between 2 points ($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;

 }

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