public inbox for newlib@sourceware.org
 help / color / mirror / Atom feed
From: Paul Zimmermann <Paul.Zimmermann@inria.fr>
To: newlib@sourceware.org
Subject: regression in tgamma?
Date: Wed, 16 Dec 2020 14:48:55 +0100	[thread overview]
Message-ID: <mw7dphdfp4.fsf@tomate.loria.fr> (raw)

       Hi,

the regression I observed also concerns the binary32 code.
Consider the following code:

$ cat /tmp/test_tgamma.c
#include <stdio.h>
#include <math.h>

#ifdef NEWLIB
int errno;
int* __errno () { return &errno; }
#endif

int main()
{
  float x = -0.0f;
  float y = tgammaf (x);
  printf ("x=%a y=%a\n", x, y);
  {
    double x = -0x1.53f198fe3b278p+7, y;
    y = tgamma (x);
    printf ("x=%a y=%a\n", x, y);
  }
}

With commit a0d7982ff486292540078c0121a435013c5ee1ea it gives on x86_64/linux
(Intel(R) Core(TM) i5-4590):

$ gcc -no-pie -DNEWLIB /tmp/test_tgamma.c build/x86_64/newlib/libm/tmp/libm.a
$ ./a.out
x=-0x0p+0 y=inf
x=-0x1.53f198fe3b278p+7 y=0x1.fd6d312572d9cp-1015

and with commit 1f8e5847dff27e504949cd21bfeadb987d36ad19:

$ gcc -no-pie -DNEWLIB /tmp/test_tgamma.c build/x86_64/newlib/libm/tmp/libm.a
$ ./a.out 
x=-0x0p+0 y=0x1p+0
x=-0x1.53f198fe3b278p+7 y=0x1p+0

Paul








             reply	other threads:[~2020-12-16 13:48 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-16 13:48 Paul Zimmermann [this message]
2020-12-16 20:31 ` Jeff Johnston
2020-12-17  7:29   ` Paul Zimmermann
2020-12-17 16:13     ` Keith Packard
2020-12-17 18:27       ` Jeff Johnston
2020-12-17 19:16         ` Keith Packard
2020-12-17 21:28           ` Jeff Johnston
2020-12-18  6:36             ` Paul Zimmermann
2020-12-18  8:42               ` Corinna Vinschen
2020-12-18  8:54                 ` Paul Zimmermann
2020-12-18  9:07                   ` Corinna Vinschen
2020-12-18 17:42                     ` Jeff Johnston
2020-12-18  8:37             ` Paul Zimmermann
  -- strict thread matches above, loose matches on Subject: below --
2020-12-15 13:35 Paul Zimmermann
2020-12-15 17:11 ` Jeff Johnston
2020-12-16  6:36   ` Paul Zimmermann

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=mw7dphdfp4.fsf@tomate.loria.fr \
    --to=paul.zimmermann@inria.fr \
    --cc=newlib@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: 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).