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[Bug math/14803] Different ULPs depending on size of long int in GCC
- From: "hjl.tools at gmail dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: Sun, 04 Nov 2012 23:02:52 +0000
- Subject: [Bug math/14803] Different ULPs depending on size of long int in GCC
- Auto-submitted: auto-generated
- References: <bug-14803-131@http.sourceware.org/bugzilla/>
http://sourceware.org/bugzilla/show_bug.cgi?id=14803
--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> 2012-11-04 23:02:52 UTC ---
(In reply to comment #1)
> On Sun, 4 Nov 2012, hjl.tools at gmail dot com wrote:
>
> > Since GCC encodes float-pointing constants slightly different,
> > depend on size of long int:
>
> Which constants are involved here? Ones in the asinl source code, or ones
> in the expected test results? In either case we should regenerate the
> affected constant in hex float or with more decimal places, though I don't
> know offhand the right software for recomputing the rational function
> approximation for asinl.
It is:
ieee754/ldbl-96/e_asinl.c: pio2_hi =
1.5707963267948966192021943710788178805159986950457096099853515625L,
32-bit long GCC encodes it as
1.57079632679489661925640447970309310221637133509
and 64-bit long GCC encodes it as
1.57079632679489661914798426245454265881562605500221252441
This difference causes the extra ULP.
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