Haversine formula with php

Question

I want to use this formula with php. I have a database with some values of latitute and longitude saved.

I want to find, with a certain value of latitude and longit

Answer 1

from this link:

function getDistance($latitude1, $longitude1, $latitude2, $longitude2) {
    $earth_radius = 6371;

    $dLat = deg2rad($latitude2 - $latitude1);
    $dLon = deg2rad($longitude2 - $longitude1);

    $a = sin($dLat/2) * sin($dLat/2) + cos(deg2rad($latitude1)) * cos(deg2rad($latitude2)) * sin($dLon/2) * sin($dLon/2);
    $c = 2 * asin(sqrt($a));
    $d = $earth_radius * $c;

    return $d;
}

As you can see there are many differences between this as your code. I don't know if you have either a different approach to the formula or maybe some step when converting to PHP went wrong, but the above formula should work.