01.
function
distance(
$lat1
,
$lon1
,
$lat2
,
$lon2
,
$unit
) {
02.
$theta
=
$lon1
-
$lon2
;
03.
$dist
= sin(
deg2rad
(
$lat1
)) * sin(
deg2rad
(
$lat2
)) +
cos
(
deg2rad
(
$lat1
)) *
cos
(
deg2rad
(
$lat2
)) *
cos
(
deg2rad
(
$theta
));
04.
$dist
=
acos
(
$dist
);
05.
$dist
= rad2deg(
$dist
);
06.
$miles
=
$dist
* 60 * 1.1515;
07.
$unit
=
strtoupper
(
$unit
);
08.
09.
if
(
$unit
==
"K"
) {
10.
return
(
$miles
* 1.609344);
11.
}
else
if
(
$unit
==
"N"
) {
12.
return
(
$miles
* 0.8684);
13.
}
else
{
14.
return
$miles
;
15.
}
16.
}