PHP calculates the distance between two GPS coordinates of Baidu map _php Tips

This article describes the PHP calculation of Baidu map Two GPS coordinates of the distance between the method. Share to everyone for your reference.

The implementation methods are as follows:

Copy Code code as follows:

/**
* Calculate the distance between two coordinates (m)
* @param float $fP 1Lat starting point (latitude)
* @param float $fP 1Lon starting point (longitude)
* @param float $fP 2Lat end point (latitude)
* @param float $fP 2Lon end point (longitude)
* @return int
*/
function Distancebetween ($fP 1Lat, $fP 1Lon, $fP 2Lat, $fP 2Lon) {
$fEARTH _radius = 6378137;
Angle converted into radians
$fRadLon 1 = Deg2rad ($fP 1Lon);
$fRadLon 2 = Deg2rad ($fP 2Lon);
$fRadLat 1 = Deg2rad ($fP 1Lat);
$fRadLat 2 = Deg2rad ($fP 2Lat);
Calculate the difference of longitude and latitude
$fD 1 = ABS ($fRadLat 1-$fRadLat 2);
$fD 2 = ABS ($fRadLon 1-$fRadLon 2);
Distance calculation
$fP = Pow (sin ($fD 1/2), 2) +
cos ($fRadLat 1) * cos ($fRadLat 2) * POW (sin ($fD 2/2), 2);
Return Intval ($fEARTH _radius * 2 * ASIN (SQRT ($fP)) + 0.5);
}
/**
* Baidu coordinate system converted into standard GPS seating system
* @param float $lnglat coordinates (for example: 106.426, 29.553404)
* @return The standard GPS value after string conversion:
*/
function bd09lltowgs84 ($fLng, $fLat) {//longitude, Latitude
$lnglat = Explode (', ', $lnglat);
List ($x, $y) = $lnglat;
$Baidu _server = "http://api.map.baidu.com/ag/coord/convert?from=0&to=4&x={$x}&y={$y}";
$result = @file_get_contents ($Baidu _server);
$json = Json_decode ($result);
if ($json->error = = 0) {
$BX = Base64_decode ($json->x);
$by = Base64_decode ($json->y);
$GPS _x = 2 * $x-$BX;
$GPS _y = 2 * $y-$by;
return $GPS _x ', '. $GPS _y;//Longitude, latitude
}else
return $lnglat;
}

I hope this article will help you with your PHP program design.