php 根据两点间的经纬度计算距离

/**
 *  @desc 根据两点间的经纬度计算距离
 *  @param float $lat 纬度值
 *  @param float $lng 经度值
 */
public function getDistance($lat1, $lng1, $lat2, $lng2)    {
   $earthRadius = 6367000;

   $lat1 = ($lat1 * pi() ) / 180;
   $lng1 = ($lng1 * pi() ) / 180;

   $lat2 = ($lat2 * pi() ) / 180;
   $lng2 = ($lng2 * pi() ) / 180;

   $calcLongitude = $lng2 - $lng1;
   $calcLatitude = $lat2 - $lat1;
   $stepOne = pow(sin($calcLatitude / 2), 2) + cos($lat1) * cos($lat2) * pow(sin($calcLongitude / 2), 2);  $stepTwo = 2 * asin(min(1, sqrt($stepOne)));
   $calculatedDistance = $earthRadius * $stepTwo;

   return round($calculatedDistance);
}