PHP根据两点间的坐标计算距离

<?php
/**
*@desc根据两点间的经纬度计算距离
*@paramfloat $lat纬度值
*@paramfloat $lng经度值
*/
functiongetDistance($lat1,$lng1,$lat2,$lng2)
{
$earthRadius=6367000;//approximate radius of earth in meters

/*
Convert these degrees to radians
to work with the formula
*/

$lat1=($lat1* pi()) / 180;
$lng1=($lng1* pi()) / 180;

$lat2=($lat2* pi()) / 180;
$lng2=($lng2* pi()) / 180;

/*
Using the
Haversine formula http://en.wikipedia.org/wiki/Haversine_formula calculate the distance
*/
$calcLongitude=$lng2-$lng1;
$calcLatitude=$lat2-$lat1;
$stepOne= pow(sin($calcLatitude/2),2) + cos($lat1) * cos($lat2) * pow(sin($calcLongitude/2),2);
$stepTwo=2* asin(min(1, sqrt($stepOne)));
$calculatedDistance=$earthRadius*$stepTwo;
returnround($calculatedDistance);
}
?>