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[Bug libquadmath/63488] large errors in y0q
- From: "sgk at troutmask dot apl.washington.edu" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 09 Oct 2014 17:45:37 +0000
- Subject: [Bug libquadmath/63488] large errors in y0q
- Auto-submitted: auto-generated
- References: <bug-63488-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63488
--- Comment #6 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Thu, Oct 09, 2014 at 05:34:11PM +0000, kargl at gcc dot gnu.org wrote:
>
> Testing 10000 values in a small interval about the lowest
> 10 zeros, the double precision y0() on FreeBSD (which comes
> from fdlibm) has
>
> ULP: 5918, x = 8.9358398197930655e-01
> ULP: 15390, x = 3.9576788857941221e+00
> ULP: 17833, x = 7.0860502172517021e+00
> ULP: 2510, x = 1.0222342340788490e+01
> ULP: 4396, x = 1.3361094710349882e+01
> ULP: 1203, x = 1.6500927187922073e+01
> ULP: 14157, x = 1.9641309720499763e+01
> ULP: 2141, x = 2.2782032287080856e+01
> ULP: 1048, x = 2.5922964874664050e+01
> ULP: 2219, x = 2.9064027475248540e+01
>
> Note, I did not try to find the worse case.
>
Well, I got curious. Testing 100000 values in the
small interval leads to
ULP: 346703, x = 8.9357674518326613e-01
ULP: 35183, x = 3.9576806238853104e+00
ULP: 69132, x = 7.0860511452537809e+00
ULP: 20098, x = 1.0222345745863045e+01
ULP: 51085, x = 1.3361097371042554e+01
ULP: 26333, x = 1.6500923006962172e+01
ULP: 17190, x = 1.9641309648491845e+01
ULP: 33541, x = 2.2782028293341551e+01
ULP: 18156, x = 2.5922956940291275e+01
ULP: 4118, x = 2.9064029588681016e+01