On Fri, Aug 07, 2009 at 10:29:27AM -0500, Kenneth Marshall wrote:
> On Fri, Aug 07, 2009 at 04:16:56PM +0100, Sam Mason wrote:
> > points in PG [..] don't
> > arbitrarily go jumping off millions of miles away or being annihilated
> > by their anti-particle just because it's possible.
> It was definitely a tongue-in-cheek response since QT is not really
> a topic for this mailing list.
Yup, I know. Hence my somewhat over the top examples.
> > I would agree with Paul that EPSILON is a hack and probably should be
> > removed. However it will cause user visible changes so it's not quite
> > as simple as that to change. I don't have anything really very useful
> > to add apart from saying that maybe the default should be the other way
> > around?
>
> However, removing EPSILON completely
> is not a good idea for the exact reason it was included originally.
Hum, I think it's good in some limited situations but not by default. I
personally think that PG should be exposing rawer access here, mainly
because FP math is hard to get right and the more we fiddle trying to
make it easier to appear to do the right thing in the common case the
more general cases become impossible. It's similar to the auto TEXT
casting thing that was changed in 8.3, but at least you get a nice error
when things aren't automatically cast to TEXT.
There are also much more reliable ways of solving the inaccuracies than
what's done now by just relying on a simple test, interval arithmetic
is my favorite at the moment but it is slower and can make thins more
complicated.
-- Sam http://samason.me.uk/
