From: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
To: "mwelinder@gmail.com" <mwelinder@gmail.com>
Cc: 'GNU C Library' <libc-alpha@sourceware.org>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Subject: Man page issues: logb, significand, cbrt, log2, log10, exp10
Date: Mon, 4 Mar 2024 15:29:00 +0000 [thread overview]
Message-ID: <PAWPR08MB8982BDA236461B6890D6F88583232@PAWPR08MB8982.eurprd08.prod.outlook.com> (raw)
Hi,
> FWIW, it appears that the author of the glibc exp10 implementation
> agrees with me that the implementation is sub-standard:
As Adhemerval pointed out, that was not the implementation used in GLIBC.
The version that was used, wasn't perfect, but still better than MUSL:
> Compare with musl:
>
> https://github.com/rofl0r/musl/blob/master/src/math/exp10.c
The worst case error of MUSL is 4.14 ULP vs 2.01 ULP of the old GLIBC exp10 [1].
And the new exp10 in GLIBC is 0.513 ULP [2].
As I pointed out in the PR, it would be reasonable for compilers to convert
pow (10, x) into exp10 (x) when it is known there is a good implementation
available - in GLIBC, exp10 is both faster and slightly more accurate than pow.
Cheers,
Wilco
[1] https://members.loria.fr/PZimmermann/papers/glibc238-20230921.pdf
[2] https://members.loria.fr/PZimmermann/papers/accuracy.pdf
next reply other threads:[~2024-03-04 15:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-04 15:29 Wilco Dijkstra [this message]
2024-03-05 8:14 ` Paul Zimmermann
[not found] <CANv4PNkVv_0eLgiSP3L_KfC-eZJaVLZ5AP1AGfD0GNrR5M4Hrg@mail.gmail.com>
[not found] ` <ZeEnJB96mMC5bfBz@debian>
[not found] ` <CANv4PNmMpiwfv5acr7U6VEVe7PE_AMTzkkpNoNN9jrtVzk_93Q@mail.gmail.com>
2024-03-02 21:54 ` Alejandro Colomar
2024-03-03 2:02 ` Morten Welinder
2024-03-03 2:21 ` Alejandro Colomar
2024-03-03 11:46 ` Vincent Lefevre
2024-03-03 12:21 ` Alejandro Colomar
2024-03-03 22:26 ` Morten Welinder
2024-03-04 12:17 ` Adhemerval Zanella Netto
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=PAWPR08MB8982BDA236461B6890D6F88583232@PAWPR08MB8982.eurprd08.prod.outlook.com \
--to=wilco.dijkstra@arm.com \
--cc=adhemerval.zanella@linaro.org \
--cc=libc-alpha@sourceware.org \
--cc=mwelinder@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).