From: "dblasby at openplans.org" <dblasby@openplans.org>
Date: Mon, 18 Jul 2005 13:35:51 -0400
Subject: [postgis-users] (no subject)
Message-ID: <1121708151.42dbe877e36eb@webmail.limegroup.com>

>This sounds like floating point comparisons failing because
>> of numerical
>> rounding issues.
>
>Highly unlikely - JTS/GEOS is very robust wrt predicates.

I think he means the 2 geometries arent actually identical - the points
maybe "10-7 off".  These differences would be hidden by converting to
WKT (since it doesnt show all 64bits of precision).

Try something like this:

SELECT encode( asBinary(  geometry1 ) , 'hex'),
       encode( asBinary(  geometry2 ) , 'hex')
FROM ... ;

And see if the two are actually equal.

dave





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