[Bug math/1163] sinf inaccurate for some inputs

[Bug math/1163] sinf inaccurate for some inputs

[jsm28 at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=1163

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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             Status|SUSPENDED                   |NEW
         AssignedTo|aj at suse dot de           |unassigned at sourceware
                   |                            |dot org

--- Comment #4 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-02-22 21:53:08 UTC ---
Still present, should be added to the testsuite.

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[Bug math/1163] sinf inaccurate for some inputs

[liubov.dmitrieva at gmail dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=1163

Liubov Dmitrieva <liubov.dmitrieva at gmail dot com> changed:

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                 CC|                            |liubov.dmitrieva at gmail
                   |                            |dot com

--- Comment #5 from Liubov Dmitrieva <liubov.dmitrieva at gmail dot com> 2012-06-22 18:08:04 UTC ---
There are many inputs give results that are wrong by more than 1 ulp for sinf()
in sysdeps/ieee754/flt-32, and for cosf - also...

I unintentionally attached my data to another tracker: 
http://sourceware.org/bugzilla/show_bug.cgi?id=5997

Summary is: Intel proprietary test system observed ~1.4 ulp errors on usual
arguments, and observed total loss of accuracy on |x| > 1e30 for current glibc
routines which use the flt-32 C implementations

I've submitted a patch proposed new implementation which solves the issue for
all architectures with SSE2 support and significantly improves performance.

http://sourceware.org/ml/libc-alpha/2012-06/msg00624.html

I intend submit a patch with x86_64 Sse2 implementation of sinf and cosf as
well.

New Asm versions, provided by Intel, are maximum 0.500121 ulp for sinf,
0.500573 ulp for cosf.

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[Bug math/1163] sinf inaccurate for some inputs

[joseph at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=1163

--- Comment #6 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2012-06-22 18:58:55 UTC ---
On Fri, 22 Jun 2012, liubov.dmitrieva at gmail dot com wrote:

> I unintentionally attached my data to another tracker: 
> http://sourceware.org/bugzilla/show_bug.cgi?id=5997
> 
> Summary is: Intel proprietary test system observed ~1.4 ulp errors on usual
> arguments, and observed total loss of accuracy on |x| > 1e30 for current glibc
> routines which use the flt-32 C implementations

Do those total-loss-of-accuracy failures appear on x86_64?  If not, then 
you should file a new bug and put the data in that bug, rather than using 
this one, which is about x86_64 not 32-bit x86.

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[Bug math/1163] sinf inaccurate for some inputs

[joseph at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=1163

--- Comment #7 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2012-06-22 19:54:04 UTC ---
On Fri, 22 Jun 2012, joseph at codesourcery dot com wrote:

> Do those total-loss-of-accuracy failures appear on x86_64?  If not, then 
> you should file a new bug and put the data in that bug, rather than using 
> this one, which is about x86_64 not 32-bit x86.

I can reproduce problems on x86_64, although with different bad results 
from x86.  But, you should still file a *new* bug for these problems, 
since it seems quite clear that the range-reduction-accuracy problems can 
sensibly be fixed separately from the not-correctly-rounded issues this 
bug is about.  In general, unless it is clear that two issues can only 
sensibly be fixed together, they should have *separate* bugs filed; always 
err on the side of filing duplicate bugs rather than confusing an existing 
bug with something that might not be fixed together with the originally 
reported issue.

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[Bug math/1163] sinf inaccurate for some inputs

[joseph at codesourcery dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=1163

--- Comment #8 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2012-06-22 20:45:15 UTC ---
I've filed bug 14283 for the cases of large errors.  Please keep this bug 
for the matter of results that, although not correctly rounded, are within 
the general range (< 10 ulp) of errors recorded in libm-test-ulps files.

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[Bug math/1163] sinf inaccurate for some inputs

[jsm28 at gcc dot gnu.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=1163

Joseph Myers <jsm28 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE

--- Comment #9 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-10-24 12:43:43 UTC ---
Collecting all reports of few-ulps errors together in one meta-bug.

*** This bug has been marked as a duplicate of bug 14759 ***

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[Bug math/1163] sinf inaccurate for some inputs

[jvdelisle at gcc dot gnu dot org]

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[Bug math/1163] sinf inaccurate for some inputs

[jvdelisle at gcc dot gnu dot org]

------- Additional Comments From jvdelisle at gcc dot gnu dot org  2008-03-29 04:28 -------
Also see gcc bug 34128 where g77 uses sin and gfortran uses sinf.  

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34128

sinf is grossly slower.

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[Bug math/1163] sinf inaccurate for some inputs

[aj at suse dot de]

------- Additional Comments From aj at suse dot de  2005-12-30 09:33 -------
We will not change this unless somebody provides a better implementation.

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[Bug math/1163] sinf inaccurate for some inputs

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2005-10-15 23:47 -------
Once somebody provides a better implementation we can use it.

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