php中根据经纬度算出与我的位置的距离

public function getDistance($lat1, $lng1, $lat2, $lng2) {
    // 赤道半径(单位m)
    $earthRadius = 6378137;
  //lat1  lng1  = 我的位置经纬度
　// lat2  lng2  = 商家位置经纬度 
    $lat1 = ($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;
    
    $new = abs($calculatedDistance);
    if($new < 1000){
        return $new . 'm';
    }else{
        return abs(round($calculatedDistance/1000, 2)) . 'km';
    }