<?php

// This code comes from http://code.calum.org/

function getbearing($oldlat, $oldlon, $newlat, $newlon ) {

        if ($newlon == $oldlon){
            if ($newlat < $oldlat)
                return 180;
            else
                return 0;
        }

        if ($newlat == $oldlat){
            if ($newlon > $oldlon)
                return 90;
            else if ($newlon < $oldlon)
                return 270;
        }

        if (($newlat > $oldlat) && ($newlon > $oldlon)) {
            $difflat = abs($newlat - $oldlat);
            $difflon = abs($newlon - $oldlon );
            $ratio = $difflon / $difflat;
            $tmp = atan( $ratio  );
            return rad2deg($tmp);
        } else if (($newlon > $oldlon) && ($newlat < $oldlat))
            return 180 - rad2deg(atan( abs( $newlon - $oldlon ) / abs($newlat - $oldlat) ));
        else if (($newlat < $oldlat) && ($newlon < $oldlon)) {
            $difflat = abs($newlat - $oldlat);
            $difflon = abs($newlon - $oldlon );
            $ratio = $difflon/ $difflat;
            $tmp = atan( $ratio  );
            return 180 + rad2deg($tmp);
        } else {
            $difflat = abs($newlat - $oldlat);
            $difflon = abs($newlon - $oldlon );
            $ratio = $difflon / $difflat;
            $tmp = atan( $ratio  );
            return 360 - rad2deg($tmp);
        }

    }

?>