n1.geom = n2.geom is not binary equal, it is bounding box equal which may include rounding errors?
st_asbinary(n1.geom) = st_asbinary(n2.geom) is binary equal > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On > Behalf Of William Temperley > Sent: Friday, January 08, 2010 7:28 AM > To: [email protected] > Subject: [postgis-users] st_equals strangeness > > > 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
