public inbox for glibc-bugs@sourceware.org help / color / mirror / Atom feed
From: "newbie-02 at gmx dot de" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sourceware.org Subject: [Bug math/31426] New: log10( 10^n ) poor accuracy in bin80 datatype, log10l( 1E+07l ) -> 7.000000000000000000434... Date: Wed, 28 Feb 2024 11:32:09 +0000 [thread overview] Message-ID: <bug-31426-131@http.sourceware.org/bugzilla/> (raw) https://sourceware.org/bugzilla/show_bug.cgi?id=31426 Bug ID: 31426 Summary: log10( 10^n ) poor accuracy in bin80 datatype, log10l( 1E+07l ) -> 7.000000000000000000434... Product: glibc Version: unspecified Status: UNCONFIRMED Severity: normal Priority: P2 Component: math Assignee: unassigned at sourceware dot org Reporter: newbie-02 at gmx dot de Target Milestone: --- Created attachment 15381 --> https://sourceware.org/bugzilla/attachment.cgi?id=15381&action=edit Snippet demonstrating log10l imprecision. hello @all, quite sure you'll tell me it's not a bug but the 'feature of imprecision' in bin-FP-math :-( log10l( 1E+07l ) produces 7.000000000000000000434..., while logl( 1E+07l ) / logl( 10.0l ) would hold with 7.0, Same as with pow10s, having them exact at integral powers of ten would help to form a reliable grid of stable points, and find better ways for correct rounding, which would help for better math. Thus if possible to improve without messing other points I'd appreciate, if not I'd like some explanation why and which calculation path is taken / preferred, and a code pointer to have a look myself. 'Me bad' is always an option, tried to evaluate and present with best intention and skills available. If 'notabug' pls. leave open or unconfirmed as hook for others who at some time in the future might have a good idea. -- You are receiving this mail because: You are on the CC list for the bug.
next reply other threads:[~2024-02-28 11:32 UTC|newest] Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-02-28 11:32 newbie-02 at gmx dot de [this message] 2024-02-28 11:49 ` [Bug math/31426] " schwab@linux-m68k.org 2024-02-28 12:49 ` newbie-02 at gmx dot de
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=bug-31426-131@http.sourceware.org/bugzilla/ \ --to=sourceware-bugzilla@sourceware.org \ --cc=glibc-bugs@sourceware.org \ /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: linkBe 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).