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From: "zimmerma+gcc at loria dot fr" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug math/26983] New: [x86_64] x86_64 tgamma has too large ULP error
Date: Mon, 30 Nov 2020 10:33:10 +0000	[thread overview]
Message-ID: <bug-26983-131@http.sourceware.org/bugzilla/> (raw)

https://sourceware.org/bugzilla/show_bug.cgi?id=26983

            Bug ID: 26983
           Summary: [x86_64] x86_64 tgamma has too large ULP error
           Product: glibc
           Version: 2.32
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: math
          Assignee: unassigned at sourceware dot org
          Reporter: zimmerma+gcc at loria dot fr
                CC: joseph at codesourcery dot com
  Target Milestone: ---

$ cat test2.c
#include <stdio.h>
#include <math.h>

int main()
{
  double x = -0x1.62c4d519e8677p+3, y;
  y = tgamma (x);
  printf ("x=%a y=%a\n", x, y);
}

$ gcc -fno-builtin test2.c -lm
$ ./a.out
x=-0x1.62c4d519e8677p+3 y=0x1.fd63c481c16c9p-23

The correctly rounded result is 0x1.fd63c481c16bfp-23, which is 10 ulps apart.
This is larger than the maximum accepted error (9 ulps).

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             reply	other threads:[~2020-11-30 10:33 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-30 10:33 zimmerma+gcc at loria dot fr [this message]
2020-12-01 23:51 ` [Bug math/26983] " woodard at redhat dot com
2020-12-07 10:32 ` zimmerma+gcc at loria dot fr
2021-04-07 11:33 ` zimmerma+gcc at loria dot fr
2021-04-07 11:34 ` zimmerma+gcc at loria dot fr
2021-04-07 11:43 ` zimmerma+gcc at loria dot fr

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