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Re: [v3] FP printing, take 2
- From: Paolo Carlini <pcarlini at suse dot de>
- To: Jerry Quinn <jlquinn at optonline dot net>
- Cc: libstdc++ at gcc dot gnu dot org
- Date: Thu, 2 Sep 2004 19:17:46 +0200 (CEST)
- Subject: Re: [v3] FP printing, take 2
- Organization: SuSE Linux AG
- References: <16691.54895.612575.291103@localhost.localdomain> <41343522.5010501@suse.de> <16692.28627.408035.820061@localhost.localdomain>
Hi Jerry,
and, first, sorry for late replying, I'm traveling
> > I wanted to ask how are you testing the ongoing work: I remember you
> > had
> > a script comparing printf to the inserters and that we still had
> > some
> > minor problems (proably false alarms) in corner cases... I would be
> > happy to run something similar on a few 64-bit architectures but
> > maybe I
> > will not be really able to do that during the next 1 & half week or
> > so.
> > Let's keep in touch.
>
> I still use the same program. It had the core code being called
> directly and
> compared the results to sprintf. I run about half a million random or
> regular
> numbers through looking for differences. The only ones I see are:
>
> mine glibc
> 0.0001 1e-04 %g style
> 1e00 1e-00 %e style
>
> In both cases I think glibc is wrong, based on printf docs around the
> web. I
> don't have the C standard, so I can't confirm, though.
Ok, thanks for the details. I'll try to investigate this issue in detail
during the next days.
> I'd be happy to send you the test prog for 64 bits. I need to pull it
> off the
> machine it's sitting on.
I would appreciate that, thanks in advance.
> > Another unrelated comment: are you taking into account in the design
> > that bug with grouping & zero precision (no decimal point, anyway)
> > that
> > I mentioned some time ago? Basically, we look for the decimal point
> > and
> > we group everything to its left: if we don't find it, we group also
> > the
> > exponential part, if present! Fixing it in the current framework its
> > feasible but very ugly, and I was wondering whether we can arrange
> > for
> > the new framework to make it easier...
>
> I remember there being an issue, but I haven't paid attention to it in
> this
> work. I'll think about whether this stuff makes it any easier. I'm not
> sure
> it does. What's the PR?
There is no PR, yet, probably I should file one: for now is all in my
paranoid mind ;) Seriously, we have a real long standing bug, albeit for
a rather uncommon case (thousands separators + no decimal point). The
issue is rather clear, anyway and constructing a testcase should be
straightforward.
Paolo.