off-line reverse geocoding solution

I have a dat开发者_如何学Goabase of places with lat/lng and I have incoming requests with lat/lng. I'd like to find the closest lat/lng in the database to the incoming request. Is there any existing library or algorithm for doing this? Searching online keeps pointing me to Google's reverse geocoding library which isn't quite what I had in mind.

As always, any help is absurdly appreciated. :)

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You dont really need an online service for this. Just apply the correct mathematical formula. See here for some examples (in JavaScript etc)...

http://www.movable-type.co.uk/scripts/latlong.html

Another alternative formula is here...

http://wiki.answers.com/Q/What_is_the_formula_for_distance_using_latitude_and_longitude