[Python-Dev] Minutes from the Numeric Coercion dev-day session

[Guido van Rossum]

[me]
> > You know where I'm leaning...  I don't know that newbies are genuinely
> > hurt by FP.  If we do it right, the naive ones will try 11.0/10.0, see
> > that it prints 1.1, and be happy; the persistent ones will try
> > 1.1**2-1.21, ask for an explanation, and get a introduction to
> > floating point.  This *doesnt'* have to explain all the details, just
> > the two facts that you can lose precision and that 1.1 isn't
> > representable exactly in binary.  Only the latter should be new to
> > them.

[Paul]
> David Ascher suggested during the talk that comparisons of floats could
> raise a warning unless you turned that warning off (which only
> knowledgable people would do). I think that would go a long way to
> helping them find and deal with serious floating point inaccuracies in
> their code.

You mean only for == and !=, right?  This could easily be implemented
now that we have rich comparisons.  We should wait until 2.2 though --
we haven't clearly decided that this is the way we want to go.

--Guido van Rossum (home page: http://www.python.org/~guido/)