Algorithm to find all Latitude Longitude locations within a certain distance from a given Lat Lng location

Question

Given a database of places with Latitude + Longitude locations, such as 40.8120390, -73.4889650, how would I find all locations within a given distance of a specific locatio

Answer 1

Since you say that any language is acceptable, the natural choice is PostGIS:

SELECT * FROM places
WHERE ST_DistanceSpheroid(geom, $location, $spheroid) < $max_metres;

If you want to use WGS datum, you should set $spheroid to 'SPHEROID["WGS 84",6378137,298.257223563]'

Assuming that you have indexed places by the geom column, this should be reasonably efficient.