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Re: PATCH: [BZ #14803] Different ULPs depending on size of long intin GCC


On 11/28/2012 06:38 PM, Joseph S. Myers wrote:
This discussion tailed off.  I propose this specific patch that
converts all three constants to the hex float values I gave in
<http://sourceware.org/ml/libc-alpha/2012-11/msg00183.html>, computed
using MPFR with the program given there.  Tested x86_64 and x86.

2012-11-28 Joseph Myers <joseph@codesourcery.com>

	[BZ #14803]
	* sysdeps/ieee754/ldbl-96/e_asinl.c (pio2_hi): Use hex float value
	of pi/2 rounded to nearest to 64 bits.
	(pio2_lo): Use hex float value of pi/2 - pio2_hi rounded to
	nearest to 64 bits.
	(pio4_hi): Use hex float value of pi/4 rounded to nearest to 64
	bits.

diff --git a/sysdeps/ieee754/ldbl-96/e_asinl.c b/sysdeps/ieee754/ldbl-96/e_asinl.c
index c33701f..21be255 100644
--- a/sysdeps/ieee754/ldbl-96/e_asinl.c
+++ b/sysdeps/ieee754/ldbl-96/e_asinl.c
@@ -64,9 +64,9 @@
  static const long double
    one = 1.0L,
    huge = 1.0e+4932L,
- pio2_hi = 1.5707963267948966192021943710788178805159986950457096099853515625L,
-  pio2_lo = 2.9127320560933561582586004641843300502121E-20L,
-  pio4_hi = 7.8539816339744830960109718553940894025800E-1L,
+ pio2_hi = 0x1.921fb54442d1846ap+0L,
+  pio2_lo = -0x7.6733ae8fe47c65d8p-68L,
+  pio4_hi = 0xc.90fdaa22168c235p-4L,

Could you add comments about what the values are actually? Just say "pi/2" etc like in the changes file.


Fine with that change,
Andreas

/* coefficient for R(x^2) */




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