//经纬度之间距离计算
function rad($d)
{
	return $d * 3.1415926535898 / 180.0;
}
function GetDistance($lat1, $lng1, $lat2, $lng2)
{
	$EARTH_RADIUS = 6378.137;
	$radLat1 = rad($lat1);
	//echo $radLat1;
	$radLat2 = rad($lat2);
	$a = $radLat1 - $radLat2;
	$b = rad($lng1) - rad($lng2);
	$s = 2 * asin(sqrt(pow(sin($a/2),2) +
	cos($radLat1)*cos($radLat2)*pow(sin($b/2),2)));
	$s = $s *$EARTH_RADIUS;
	$s = round($s * 10000) / 10000;
	return $s;
}