From: Randolf Richardson <rr@8x.ca>
To: pgsql-sql@postgresql.org
Subject: Re: Radius of a zip code
Date: Thu, 1 Jan 2004 04:56:24 +0000 (UTC)
Message-ID: <Xns9462D2D4F5738rr8xca@200.46.204.72> (raw)
References: <000b01c3cc09$e043fd70$0201a8c0@andy2>
<8408.1072483789@sss.pgh.pa.us>
"tgl@sss.pgh.pa.us (Tom Lane)" wrote in comp.databases.postgresql.sql:
[sNip]
> I'm guessing that the big problem is that you didn't measure longitude
> and latitude in identical units in your table, so your "circle" isn't
> real circular, and the smaller problem is that "miles" converts to
> "degrees of arc" differently at different latitudes.
Don't forget that there are two different types of "miles" which need
to be considered when measuring distances:
1 statute/land mile = 1.609 km
1 nautical/sea mile = 1.85 km
Since kilometers are consistent over land and water (and in the great
vacuum of space), the metric system should always be used to ensure clarity,
unless the only land masses the user is concerned with have no bodies of
water.
=)
--
Sir Randolf, noble spam fighter - rr@8x.ca
Vancouver, British Columbia, Canada
Please do not eMail me directly when responding
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To: pgsql-sql@postgresql.org
Cc: rr@8x.ca
Subject: Re: Radius of a zip code
In-Reply-To: <Xns9462D2D4F5738rr8xca@200.46.204.72>
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