Date: Sun, 15 Jul 2018 14:14:42 -0700 From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: Matthew Macy <mat.macy@gmail.com> Cc: "Montgomery-Smith, Stephen" <stephen@missouri.edu>, Warner Losh <imp@bsdimp.com>, Cy Schubert <Cy.Schubert@cschubert.com>, Ian Lepore <ian@freebsd.org>, "K. Macy" <kmacy@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org>, "freebsd-numerics@freebsd.org" <freebsd-numerics@freebsd.org> Subject: Re: [PATCH] Recent libm additions Message-ID: <20180715211442.GA33140@troutmask.apl.washington.edu> In-Reply-To: <CAPrugNozzxOH9_G-UAgA6XNgGkP8_giRsEVY3XMPQ0asAKwduw@mail.gmail.com> References: <20180715184255.4965AE50@spqr.komquats.com> <CANCZdfp5jOS2mLQR7GvgxTEqpG5D32tDTf2mY=BJxVXSNitLqQ@mail.gmail.com> <4c91b1a4-ecaa-337e-c6d3-89e9d4fcaf83@missouri.edu> <CAPrugNozzxOH9_G-UAgA6XNgGkP8_giRsEVY3XMPQ0asAKwduw@mail.gmail.com>
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On Sun, Jul 15, 2018 at 02:00:37PM -0700, Matthew Macy wrote:
> On Sun, Jul 15, 2018 at 12:43 PM, Montgomery-Smith, Stephen
> <stephen@missouri.edu> wrote:
> > On 07/15/2018 02:09 PM, Warner Losh wrote:
> >> I'm not saying that he has a lock. I'm saying he's are domain expert and
> >> many mistakes can be avoided by talking to him.
> >>
> >> I'm saying we have history here, and that history, while poorly documented,
> >> wasn't followed. To the extent it is poorly documented, we should fix that.
> >>
> >> Warner
> >>
> > I agree that we should document the process. Maybe also include
> > freebsd-numerics@ on these discussions, as that is why it was created.
> >
> > But I'm really glad these changes were committed. I have found the
> > people tend to drag their feet a lot on numerics issues.
> >
> > Has anyone done an analysis of the OpenBSD powl functions from an
> > accuracy point of view? That is, to test how many ULP of error these
> > functions have? If not, I could give it a go, although not for several
> > months because life is very busy.
>
> They're also used by Julia. You might ask there first.
You also need to fix the pow.3 documentation. It currently states
BUGS
To conform with newer C/C++ standards, a stub implementation
for powl was committed to the math library, where powl is mapped
to pow. Thus, the numerical accuracy is at most that of the
53-bit double precision implementation.
--
Steve
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