From: Paul Zimmermann <Paul.Zimmermann@inria.fr>
To: Jeff Johnston <jjohnstn@redhat.com>
Cc: newlib@sourceware.org, vincenzo.innocente@cern.ch
Subject: Re: huge error for pow
Date: Wed, 08 Feb 2023 08:02:14 +0100 [thread overview]
Message-ID: <mw1qn0iqrt.fsf@coriandre.loria.fr> (raw)
In-Reply-To: <CAOox84v-e50QYVF8jFkRB_kXSOnfj855o9x6HPU52vQFtz_ffg@mail.gmail.com> (message from Jeff Johnston on Tue, 7 Feb 2023 16:48:14 -0500)
Hi Jeff,
this would not make sense on our side, since in CORE-MATH we are currently
completing a correctly rounded pow function, which will be available in a
few weeks, and can then be integrated into newlib.
Best regards,
Paul
> From: Jeff Johnston <jjohnstn@redhat.com>
> Date: Tue, 7 Feb 2023 16:48:14 -0500
> Cc: newlib@sourceware.org, vincenzo.innocente@cern.ch
>
>
> [1:text/plain Show]
>
>
> [2:text/html Hide Save:noname (1kB)]
>
> Thanks Paul,
>
> Do you think you can put together a patch?
>
> -- Jeff J.
>
> On Tue, Feb 7, 2023 at 9:27 AM Paul Zimmermann <Paul.Zimmermann@inria.fr>
> wrote:
>
> Hi,
>
> while testing Newlib 4.3.0, I noticed the following huge error:
>
> zimmerma@salade:~/svn/tbd/20/src/binary64$ VERBOSE=-v ./doitb.newlib pow
> 1000
> Checking pow with newlib-4.3.0.20230120
> Using seed 1619945
> pow 0 -1 -0x1.647ff80007ff8p-576,-0x1.3d018267f12fp+48 [inf] inf inf
> libm gives inf
> mpfr gives -inf
>
> The exponent y in x^y is a large odd integer, thus since x is negative
> we
> should get a negative number as result.
>
> This issue was apparently already present in 3.3.0, but we only
> discovered
> it now.
>
> Best regards,
> Paul
next prev parent reply other threads:[~2023-02-08 7:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-07 14:27 Paul Zimmermann
2023-02-07 21:48 ` Jeff Johnston
2023-02-08 7:02 ` Paul Zimmermann [this message]
2023-04-08 6:00 Paul Zimmermann
2023-04-11 9:18 ` Corinna Vinschen
2023-04-11 9:37 ` Paul Zimmermann
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