程式設計@筆記

這的英文一個非常有用的距離計算函數，利用緯度和經度計算從一個地點到乙地點的距離。該函數可以返回英里，公里，海裡三種單位類型的距離。

function distance($lat1,$lon1,$lat2,$lon2,$unit){
$theta = $lon1 - $lon2;
$dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) + cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
$dist = acos($dist);
$dist = rad2deg($dist);
$miles = $dist * 60 * 1.1515;
$unit = strtoupper($unit);
if ($unit == "K") {
return ($miles * 1.609344);
} else if ($unit == "N") {
return ($miles * 0.8684);
} else {
return $miles;
}
}

echo distance(24.994344,121.521873,25.000005,121.520790, "k")." kilometers";