Fred, It's not that. I was only using WKT for illustration - it's not being used for comparison.
The key line is: """ (not st_equals(n1.geom, n2.geom)) and n1.geom = n2.geom; """ i.e. binary equal points are not being seen as equal by st_equal Cheers Will 2010/1/8 Fred Lehodey <[email protected]>: > Hi, > looks like truncation problem: WKT format does not maintain precision.... -> > ST_AsText() > > http://postgis.refractions.net/docs/ST_AsText.html > > Fred. > > > > > > On Fri, Jan 8, 2010 at 3:28 PM, William Temperley <[email protected]> > wrote: >> >> Dear all, >> >> Given two points with exactly the same coordinates that are binary >> equal (geom = geom), I don't understand how st_equals can return >> false. >> >> The following statement: >> >> select >> st_astext(n1.geom), >> st_astext(n2.geom) >> from nodes n1, nodes n2 >> where (n1.node_id = n2.node_id) >> and (not st_equals(n1.geom, n2.geom)) and n1.geom = n2.geom; >> >> >> yields: >> st_astext | st_astext >> >> ------------------------------------------+------------------------------------------ >> POINT(28.291805 37.0481949999918) | POINT(28.291805 >> 37.0481949999918) >> POINT(28.291805 37.0481949999918) | POINT(28.291805 >> 37.0481949999918) >> POINT(28.2538598984633 37.006806) | POINT(28.2538598984633 >> 37.006806) >> POINT(28.0726373735563 37.022361) | POINT(28.0726373735563 >> 37.022361) >> >> Could anyone shed any light on this please? >> >> POSTGIS="1.4.1" GEOS="3.1.1-CAPI-1.6.0" btw. >> >> >> Thanks >> >> Will >> _______________________________________________ >> postgis-users mailing list >> [email protected] >> http://postgis.refractions.net/mailman/listinfo/postgis-users > > _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
