Re: newlib-4.4.0 yearly snapshot created

       Hi Jeff,

I did investigate. In fact I now get the issue with tgammaf even with
Newlib 4.2.0. It might be due to a change in the compiler used (I now use
gcc 13.2.0) or in my testing framework.

Can you reproduce the issue?

For the binary64 pow function, the accuracy has greatly improved with respect
to 4.2.0. We got an error of up to 636 ulps, and now the largest error I get
after a few tests is 0.892 ulp, which is better than the Intel Math Library
for this function (1.73 ulp).

Paul

> From: Jeff Johnston <[email protected]>
> Date: Thu, 4 Jan 2024 13:44:27 -0500
> Cc: [email protected]
> 
> 
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> 
> Hi Paul, the problem you reported hasn't been solved yet and the
> snapshot is just a snapshot in time of the repo.
> 
> Looking at the logs, I only see the following gamma change that occurs
> between 4.2.0 and 4.3.0:
> 
> commit ec69debcb977d6395f9e91ee20133de473484e20
> Author: Andoni Arregi <[email protected]>
> Date:   Fri Feb 11 12:16:00 2022 +0100
> 
>     Improve lgammaf range for very small cases
>     
>     The original cut for small arguments at |x|<2**-70 (copied from the
>     double version) produces that when computing nadj we get a subnormal
>     number for t*x and thus, the division of pi/subnormal will be INF and
>     the logarithm of it too, which is wrong as a result for lgammaf in this
>     range.
>     The proposed new limit seems to be safe and has been tested to
>     produce accurate results.
>     (Courtesy of Andreas Jung, ESA)
> 
> I don't think this should have caused the regression you are seeing with -1
> as input, but can you confirm
> if it is?  Otherwise, can you use the git bisect in concert with your test
> to determine the
> source of the regression?
> 
> Thanks,
> 
> -- Jeff J.
> 
> On Thu, Jan 4, 2024 at 11:03 AM Paul Zimmermann <[email protected]>
> wrote:
> 
>         Hi Jeff,
> 
>  for what concerns the accuracy of math functions, the issue with huge
>  error
>  in pow (https://sourceware.org/pipermail/newlib/2023/020164.html) seems
>  to
>  have been fixed in 4.4.0, thanks!
> 
>  However, the regression for tgammaf(-1) with respect to 4.2.0 is still
>  there:
>  https://sourceware.org/pipermail/newlib/2023/020170.html.
> 
>  Happy New Year,
>  Paul Zimmermann
> 
>  > From: Jeff Johnston <[email protected]>
>  > Date: Sun, 31 Dec 2023 12:23:22 -0500
>  > 
>  > 
>  > [1:text/plain Show]
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>  > [2:text/html Hide Save:noname (879B)]
>  > 
>  > The 4.4.0 snapshot has been created and uploaded to the ftp site.  For
>  > details on changes, see the NEWS file.
>  > 
>  > If there are any issues, I'll have to deal with them in the New Year.
>  > 
>  > Thanks everyone for contributing last minute changes to handle the
>  > c99/gcc-14 issues and thanks to all who made contributions/reviews
>  this
>  > year.  Special thanks to Corinna for leading the project and reviewing
>  the
>  > lion's share of the code.
>  > 
>  > Happy New Year everyone,
>  > 
>  > -- Jeff J.