Re: Issue with point_ops and NaN

On Wed, 2021-03-31 at 15:48 +0900, Kyotaro Horiguchi wrote:
> > > > > > SELECT point('NaN','NaN') <@ polygon('(0,0),(1,0),(1,1),(0,0)');
> > > > > > ?column? 
> > > > > > ----------
> > > > > >   t
> > > > > >   (1 row)
> > > > 
> > > > Agreed --- one could make an argument for either 'false' or NULL
> > > > result, but surely not 'true'.
> 
> Thanks! However, Michael's suggestion is worth considering.  What do
> you think about makeing NaN-involved comparison return NULL?  If you
> agree to that, I'll make a further change to the patch.

If you think of "NaN" literally as "not a number", then FALSE would
make sense, since "not a number" implies "not a number between 0 and 1".

But since NaN is the result of operations like 0/0 or infinity - infinity,
NULL might be better.

So I'd opt for NULL too.

Yours,
Laurenz Albe