Re: locating cities within a radius of another

Oliver Kohll - Mailing Lists wrote:
>
> On 21 Jul 2010, at 23:14, Joe Conway <mail@joeconway.com
> <mailto:mail@joeconway.com>> wrote:
>
>> If you want something simple, and not requiring PostGIS, but plpgsql
>> instead, see:
>>
>> http://archives.postgresql.org/pgsql-sql/2003-12/msg00193.php
>
> For completeness, the earthdistance module also provides the distance
> between two lat/longs, the point<@>point syntax is simple to use:
> http://www.postgresql.org/docs/8.3/static/earthdistance.html

I did look at earthdistance before.  Revisiting it now, thanks.

So, I'm trying to figure out this syntax.  The docs say:

point <@> point - float8 - gives the distance in statue miles between
two points on the Earth's surface.

How does longitude and latitude fit into this picture?  I can't find any
other documentation or examples?

I've got the contrib mods installed as 'select earth()' works fine.

>
> Regards
> Oliver Kohll
>
> oliver@agilebase.co.uk <mailto:oliver@agilebase.co.uk> / +44(0)7814
> 828608 / skype:okohll
> www.agilebase.co.uk <http://www.agilebase.co.uk> - software
>


--
Until later, Geoffrey

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