This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: Fix ldbl-128ibm cos range reduction near pi/2 (bug 15359)
- From: Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Date: Thu, 09 May 2013 18:12:43 -0300
- Subject: Re: Fix ldbl-128ibm cos range reduction near pi/2 (bug 15359)
- References: <Pine dot LNX dot 4 dot 64 dot 1305092036040 dot 29757 at digraph dot polyomino dot org dot uk> <518C0E06 dot 30104 at redhat dot com>
On 09-05-2013 17:58, Carlos O'Donell wrote:
> On 05/09/2013 04:38 PM, Joseph S. Myers wrote:
>> Bug 15359 is inaccuracy of ldbl-128ibm cos near pi/2. As with the
>> ldbl-128 case, the cause is inaccurate range reduction, and like that
>> patch <http://sourceware.org/ml/libc-alpha/2013-05/msg00271.html> this
>> patch uses the full precision of long double for the high and low
>> parts of pi/2 to fix the inaccuracy. Tested powerpc to confirm the
>> large ulps no longer appear.
>>
>> 2013-05-09 Joseph Myers <joseph@codesourcery.com>
>>
>> [BZ #15359]
>> * sysdeps/ieee754/ldbl-128ibm/e_rem_pio2l.c (c): Use 106 bits for
>> high part of pi/2.
>> (__ieee754_rem_pio2l): Update comments.
> Looks good to me.
>
> I know Richard mentioned that we could do better here instead
> of using static variables, but that's orthogonal to this fix.
>
> Cheers,
> Carlos.
>
Thanks for fixing it Joseph.