Re: locating cities within a radius of another

Oliver Kohll - Mailing Lists wrote:
>
> On 22 Jul 2010, at 12:57, Geoffrey wrote:
>
>>> 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
>>
>> Disgregard my last post, Surely as soon as I hit send, the light went
>> on...  I'm looking at deriving my points for point <@> point from
>> ll_to_earth().
>
> I constructed mine using point(longitude, latitude), where long and lat
> are double precision, which returns a datatype of type point.
> ll_to_earth() looks like it returns a datatype of type earth, so not
> sure if it will work. Maybe things have changed in a recent release,
> please let me know if so.
>
> So an example would be
> select point(-2.2171,56.8952)<@>point(-1.2833,51.6667) as miles;
>       miles
> ------------------
>  363.202864676916
> (1 row)

Perfect, that appears to work for me as well, thanks.

>
> 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

"I predict future happiness for America if they can prevent
the government from wasting the labors of the people under
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- Thomas Jefferson