Fix ldbl-128ibm cos range reduction near pi/2 (bug 15359)

[Adhemerval Zanella]

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.