php计算两个坐标（经度，纬度）之间距离的方法

function distance($lat1, $lng1, $lat2, $lng2, $miles = true){ $pi80 = M_PI / 180; $lat1 *= $pi80; $lng1 *= $pi80; $lat2 *= $pi80; $lng2 *= $pi80; $r = 6372.797; // mean radius of Earth in km $dlat = $lat2 - $lat1; $dlng = $lng2 - $lng1; $a = sin($dlat/2)*sin($dlat/2)+cos($lat1)*cos($lat2)*sin($dlng/2)*sin($dlng/2); $c = 2 * atan2(sqrt($a), sqrt(1 - $a)); $km = $r * $c; return ($miles ? ($km * 0.621371192) : $km);}