Se state cercando un algoritmo per calcolare la distanza tra due coordinate in PHP, ecco a voi.
/** * Calculates the great-circle distance between two points, with * the Vincenty formula. * @param float $latitudeFrom Latitude of start point in [deg decimal] * @param float $longitudeFrom Longitude of start point in [deg decimal] * @param float $latitudeTo Latitude of target point in [deg decimal] * @param float $longitudeTo Longitude of target point in [deg decimal] * @param float $earthRadius Mean earth radius in [m] * @return float Distance between points in [m] (same as earthRadius) */ public static function vincentyGreatCircleDistance( $latitudeFrom, $longitudeFrom, $latitudeTo, $longitudeTo, $earthRadius = 6371000) { // convert from degrees to radians $latFrom = deg2rad($latitudeFrom); $lonFrom = deg2rad($longitudeFrom); $latTo = deg2rad($latitudeTo); $lonTo = deg2rad($longitudeTo); $lonDelta = $lonTo - $lonFrom; $a = pow(cos($latTo) * sin($lonDelta), 2) + pow(cos($latFrom) * sin($latTo) - sin($latFrom) * cos($latTo) * cos($lonDelta), 2); $b = sin($latFrom) * sin($latTo) + cos($latFrom) * cos($latTo) * cos($lonDelta); $angle = atan2(sqrt($a), $b); return $angle * $earthRadius; }
Fonte http://stackoverflow.com/questions/10053358/measuring-the-distance-between-two-coordinates-in-php