http://franz.com/ns/allegrograph/3.0/geospatial/inCircle
Find points in a circle using cartesian coordinates
For example:
  ?subject geo:inCircle ( ex:locationPredicate ?center ?radius) .    will bind  ?subject  to the subject of each triple found using a geospatial search centered at  ?center  and with radius  ?radius . Both  ?center  and  ?radius  must be bound before this pattern can be evaluated. 
You can also use
  (?subject ?coordinate) geo:inCircle ( ex:locationPredicate ?center ?radius) .    which acts as the above but also binds  ?coordinate  to the object of each triple returned. 
As with all geospatial magic properties, the locationPredicate must be set up with a predicate type mapping to a geospatial datatype.
Notes
The following namespace abbreviations are used:
- fti - <http://franz.com/ns/allegrograph/2.2/textindex/>
 - geo - <http://franz.com/ns/allegrograph/3.0/geospatial/>
 - geofn - <http://franz.com/ns/allegrograph/3.0/geospatial/fn/>
 - nd - <http://franz.com/ns/allegrograph/5.0/geo/nd#>
 - ndfn - <http://franz.com/ns/allegrograph/5.0/geo/nd/fn#>
 - sna - <http://franz.com/ns/allegrograph/4.11/sna/>
 
The SPARQL magic properties reference has additional information on using AllegroGraph magic properties and functions.