PHP利用经纬度计算两点之间的距离（两种方法）

/**
* @param $lat1
* @param $lng1
* @param $lat2
* @param $lng2
* @return int
*/
function getDistance($lat1, $lng1, $lat2, $lng2){

// 将角度转为狐度  
$radLat1 = deg2rad($lat1);// deg2rad()函数将角度转换为弧度
$radLat2 = deg2rad($lat2);
$radLng1 = deg2rad($lng1);
$radLng2 = deg2rad($lng2);

$a = $radLat1 - $radLat2;
$b = $radLng1 - $radLng2;

$s = 2 * asin(sqrt(pow(sin($a / 2), 2)+cos($radLat1) * cos($radLat2) * pow(sin($b / 2), 2))) * 6378.137;

return $s;

}

/**
* @param $lat1
* @param $lon1
* @param $lat2
* @param $lon2
* @param float $radius  星球半径 KM
* @return float
*/
function distance($lat1, $lon1, $lat2,$lon2,$radius = 6378.137)
{
$rad = floatval(M_PI / 180.0);

$lat1 = floatval($lat1) * $rad;
$lon1 = floatval($lon1) * $rad;
$lat2 = floatval($lat2) * $rad;
$lon2 = floatval($lon2) * $rad;

$theta = $lon2 - $lon1;

$dist = acos(sin($lat1) * sin($lat2) + cos($lat1) * cos($lat2) * cos($theta));

if ($dist < 0 ) {
$dist += M_PI;
}
    return $dist = $dist * $radius;
}
$lat1 = '31.253411';
$lon1 = '121.518998';

$lat2 = '31.277117';
$lon2 = '120.744587';

echo getDistance($lat1, $lon1, $lat2, $lon2);  // 73.734589823361
echo distance($lat1, $lon1, $lat2, $lon2);   // 73.734589823354