GeoClass helps you to handle georeferenced data (latitude and longitude values for a location).
It enables the connection to databases which provide these data or you can easily create your own GeoObjects.
Features are: circumference search in (relational) databases, handlers for NIMA-DB and openGeoDB, distance calculation, creation of maps from .e00 or .ovl files and more (rdf, soap, etc).
If you know the location of two places you can search out the distance between these and the orientation from one location to the other.
One benefit of GeoClass.php is the support of RDF-files with georeferenced data as defined by the w3.org.
A GeoObject can be coverted to a RDF-file and a RDF-file can be parsed an outputted as an array of GeoObjects.