[postgis-users] st_equals strangeness

[William Temperley]

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