[postgis-devel] RC5 problem

[strk at refractions.net]

This should be the behaviour since RC1.
Note that box3d is double precision, while box2d is
single precision. So you can choose which one to use.
Example:

strk=# select xmin('POINT(1.0000000001 0)'::geometry::box3d);
     xmin
--------------
 1.0000000001
(1 row)

strk=# select xmin('POINT(1.0000000001 0)'::geometry::box2d);
 xmin
------
    1
(1 row)

Also note that geometry::box3d always *computes* the bounding
box while geometry::box2d uses the bbox cache if available
(which is the single-precision version).

--strk;

On Sat, Mar 26, 2005 at 11:34:16AM -0500, Carl Anderson wrote:
> 
> not sure when this came up,  I did not try other recent RC's
> 
> select xmin(<geometry>);    
> is confused by the parallel IMPLICIT casts from geometry to BOX2d and BOX3d
> and the existence of
>    xmin(box2d)
> and
>   xmin(box3d)
> 
> additional IMPLICIT casts
>    box2d(box3d)
>    box3d(box2d)
>  
> the IMPLICIT casts seem potentially circular,  wherein it might become 
> impossible to
> clearly understand what chain of casts occurred and in what order.
> 
> select xmin(geometry('POINT(0 0)'));
> select xmin('POINT(0 0)'::geometry);
>   ERROR:  function xmin(geometry) is not unique
>   HINT:  Could not choose a best candidate function. You may need to 
> add explicit type casts.
> 
> 
> these are ok
> select xmin('POINT(0 0)'::geometry::box2d);  
> select xmin('POINT(0 0)'::geometry::box3d); 
> select xmin('POINT(0 0)'::geometry::box3d::box2d);
> select xmin('POINT(0 0)'::geometry::box2d::box3d);
> 
> C.
> 
> 
> 
> 
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