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[Bug math/13381] rounding problem wih sincosl
- From: "vincent-srcware at vinc17 dot net" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: Wed, 09 Nov 2011 00:48:59 +0000
- Subject: [Bug math/13381] rounding problem wih sincosl
- Auto-submitted: auto-generated
- References: <bug-13381-131@http.sourceware.org/bugzilla/>
http://sourceware.org/bugzilla/show_bug.cgi?id=13381
Vincent LefÃvre <vincent-srcware at vinc17 dot net> changed:
What |Removed |Added
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CC| |vincent-srcware at vinc17
| |dot net
--- Comment #5 from Vincent LefÃvre <vincent-srcware at vinc17 dot net> 2011-11-09 00:48:59 UTC ---
The AMD Opteron doesn't have this "bug".
Now, there's a much more important problem than the rounding, on both Intel and
AMD processors: the fact that their implementation is broken due to the lack of
accurate range reduction. Try with X = 1.0e22 and compare the results obtained
with -O0 (hardware implementation) and -O3 (obtained with MPFR, I suppose, thus
correct).
In short, the hardware implementation must not be used. If the user wants a
fast implementation but incorrect results on large values, he can still use
compiler options like -ffast-math, with which the compiler would generate
hardware instructions directly.
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