I have a problem with implementing variables into a function that calculate distance between 2 latitudes, longitudes.
One of them is constant, and the second one being passed from the form.

Here is the code:

PHP Code:
$lon1 $_POST['lon1'];
$lat1 $_POST['lat1'];
$lon2 '-0.30020239';
$lat2 '51.58734910';
distance($lat11$lon11$lat22$lon22) { 
$theta $lon11 $lon22
$dist sin(deg2rad($lat11)) * sin(deg2rad($lat22)) +  cos(deg2rad($lat11)) * cos(deg2rad($lat22)) * cos(deg2rad($theta)); 
$dist acos($dist); 
$dist rad2deg($dist); 
$miles $dist 60 1.1515;

//////////  return good calculation
echo distance(52.611644, -0.2630451.58734910, -0.30020239) . " miles<br>";

////////// my way - return wrong calculation 
echo distance("$lon1""$lat1"51.58734910, -0.30020239) . " miles<br>"
As long as i have lat, lon values hardcoded is fine, but idea is to have this calculation done from variables.
Both will vary .... tried different configurations ... i'm losing it ...

How should I code it ??

Thanks for your help in advance!