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From: "Ondřej Bílka" <neleai@seznam.cz>
To: bugdal at aerifal dot cx <sourceware-bugzilla@sourceware.org>
Cc: glibc-bugs@sourceware.org
Subject: Re: [Bug math/14412] Removal of sysdeps/x86_64/fpu/s_sincos.S causes regressions
Date: Mon, 29 Apr 2013 14:04:00 -0000 [thread overview]
Message-ID: <20130429140349.GB24033@domone.kolej.mff.cuni.cz> (raw)
In-Reply-To: <bug-14412-131-pCCovGlIGm@http.sourceware.org/bugzilla/>
On Mon, Apr 29, 2013 at 01:28:10PM +0000, bugdal at aerifal dot cx wrote:
> http://sourceware.org/bugzilla/show_bug.cgi?id=14412
>
> --- Comment #33 from Rich Felker <bugdal at aerifal dot cx> 2013-04-29 13:28:10 UTC ---
> Ondrej, the results are not pure garbage. There are only two correct results
> sin(0x1p1000) can give, either of the nearest representable neighbors (less
> than 1ulp error) of the number 2**1000. Your fallacy is writing PI in your
> example. There is no such floating point number as PI, and this is part of why
> implementing correct trig functions is nontrivial; implementing ones that work
> in degree units, or a base-2 division of the unit circle, would be much easier.
>
Ok, assume you wrote function cos_deg that takes input degree in
degrees. You still have
cosdeg(360*(2**60)) == cosdeg(360*(2**60)+180)
In short when you have inputs with zero significant digits you can
expect only garbage as output.
next prev parent reply other threads:[~2013-04-29 14:04 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-26 21:08 [Bug math/14412] New: Removal of sysdeps/x86_64/fpu/s_sincos.S causes pdf rendering time regression markus at trippelsdorf dot de
2012-07-26 21:09 ` [Bug math/14412] " markus at trippelsdorf dot de
2012-07-26 21:14 ` markus at trippelsdorf dot de
2012-07-27 6:44 ` aj at suse dot de
2012-07-27 7:18 ` markus at trippelsdorf dot de
2012-07-27 12:33 ` markus at trippelsdorf dot de
2012-07-28 22:15 ` bugdal at aerifal dot cx
2012-08-03 3:51 ` carlos_odonell at mentor dot com
2012-08-09 10:14 ` markus at trippelsdorf dot de
2012-08-19 9:31 ` markus at trippelsdorf dot de
2012-08-19 9:37 ` [Bug math/14412] Removal of sysdeps/x86_64/fpu/s_sincos.S causes regressions markus at trippelsdorf dot de
2012-12-03 22:13 ` davem at davemloft dot net
2012-12-04 0:00 ` carlos at systemhalted dot org
2013-04-25 21:48 ` wbrana at gmail dot com
2013-04-25 23:35 ` carlos at redhat dot com
2013-04-25 23:58 ` bugdal at aerifal dot cx
2013-04-26 0:14 ` bugdal at aerifal dot cx
2013-04-26 2:55 ` siddhesh at redhat dot com
2013-04-26 3:08 ` bugdal at aerifal dot cx
2013-04-26 3:50 ` siddhesh at redhat dot com
2013-04-26 6:29 ` markus at trippelsdorf dot de
2013-04-26 6:40 ` jakub at redhat dot com
2013-04-26 10:00 ` siddhesh at redhat dot com
2013-04-26 11:31 ` joseph at codesourcery dot com
2013-04-26 11:33 ` joseph at codesourcery dot com
2013-04-26 11:42 ` siddhesh at redhat dot com
2013-04-26 13:52 ` bugdal at aerifal dot cx
2013-04-26 13:55 ` bugdal at aerifal dot cx
2013-04-26 15:07 ` joseph at codesourcery dot com
2013-04-26 15:20 ` wbrana at gmail dot com
2013-04-29 10:29 ` siddhesh at redhat dot com
2013-04-29 10:50 ` wbrana at gmail dot com
2013-04-29 11:55 ` bugdal at aerifal dot cx
2013-04-29 12:32 ` wbrana at gmail dot com
2013-04-29 13:21 ` Ondřej Bílka
2013-04-29 13:21 ` neleai at seznam dot cz
2013-04-29 13:28 ` bugdal at aerifal dot cx
2013-04-29 14:04 ` Ondřej Bílka [this message]
2013-04-29 13:32 ` bugdal at aerifal dot cx
2013-04-29 13:36 ` wbrana at gmail dot com
2013-04-29 13:44 ` siddhesh at redhat dot com
2013-04-29 13:51 ` bugdal at aerifal dot cx
2013-04-29 14:04 ` neleai at seznam dot cz
2013-04-29 14:19 ` siddhesh at redhat dot com
2013-04-29 14:29 ` markus at trippelsdorf dot de
2013-04-29 14:48 ` bugdal at aerifal dot cx
2013-04-29 16:29 ` Ondřej Bílka
2013-04-29 16:29 ` neleai at seznam dot cz
2013-04-29 17:30 ` bugdal at aerifal dot cx
2013-04-29 20:58 ` joseph at codesourcery dot com
2013-04-30 5:41 ` siddhesh at redhat dot com
2013-04-30 21:37 ` bugdal at aerifal dot cx
2013-05-01 22:25 ` bugdal at aerifal dot cx
2013-07-16 20:08 ` nshmyrev at yandex dot ru
2013-09-07 6:55 ` carlos at redhat dot com
2014-02-06 18:31 ` jsm28 at gcc dot gnu.org
2014-06-17 18:55 ` fweimer at redhat dot com
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