working on latitude longitude mathematics… and making a quick note of it :)
finding distance between 2 points in kilometers, which converted in PHP comes out:


$distance=sqrt((($lat2-$lat1)*($lat2-$lat1) + ($long1-$long2)*($long1-$long2)))* 3960 * 3.141592/180

Note: this is a simple application of Pythagoras theorem. For advanced calculations try Googling it.