Re: [PATCH] Recent libm additions

From: Steve Kargl <sgk_at_troutmask.apl.washington.edu>
Date: Sun, 15 Jul 2018 14:14:42 -0700
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_at_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_at_ 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
Received on Sun Jul 15 2018 - 19:14:46 UTC

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