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* [Bug math/14759] New: Most functions in math.h not correctly rounded
@ 2012-10-24 8:08 JoshuaHopp at web dot de
2012-10-24 12:39 ` [Bug math/14759] " jsm28 at gcc dot gnu.org
` (7 more replies)
0 siblings, 8 replies; 9+ messages in thread
From: JoshuaHopp at web dot de @ 2012-10-24 8:08 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14759
Bug #: 14759
Summary: Most functions in math.h not correctly rounded
Product: glibc
Version: 2.15
Status: NEW
Severity: normal
Priority: P2
Component: math
AssignedTo: unassigned@sourceware.org
ReportedBy: JoshuaHopp@web.de
Classification: Unclassified
Host: x86_64
Target: x86_64
Build: linux-gnu
Most functions in math.h do not use correct rounding. Example:
//--- snip ---
#include <math.h>
#include <fenv.h>
#include <assert.h>
int main() {
double x = 1.0; // 1.0 is exact
fesetround(FE_DOWNWARD);
double a = asin(x);
fesetround(FE_UPWARD);
double b = asin(x);
// asin(1) == pi/2, which is not exactly representable
// so, assuming correct rounding, a should be less than b
assert(a < b);
}
//--- snap ---
Compile with "gcc -lm" (or even "gcc -lm -ffloat-store -frounding-math").
Run the example:
main: Assertion `a < b' failed.
Similar results can be obtained with exp, cos, acos, atan, sinh, cosh, atanh,
asinh and acosh.
------
Kernel version: 3.5.2-1.fc17
gcc version 4.7.2 20120921 (Red Hat 4.7.2-2) (GCC)
GNU ld version 2.22.52.0.1-10.fc17 20120131
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* [Bug math/14759] Most functions in math.h not correctly rounded
2012-10-24 8:08 [Bug math/14759] New: Most functions in math.h not correctly rounded JoshuaHopp at web dot de
@ 2012-10-24 12:39 ` jsm28 at gcc dot gnu.org
2012-10-24 12:42 ` jsm28 at gcc dot gnu.org
` (6 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2012-10-24 12:39 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14759
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |SUSPENDED
--- Comment #1 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-10-24 12:39:29 UTC ---
I'll use this as the general meta-bug for not-correctly-rounding functions
(other than those with fully specified results such as sqrt and fma), as I
suggested in <http://sourceware.org/ml/libc-alpha/2012-02/msg00392.html>, and
mark other bugs for small ulps errors (say 1-10ulps) as duplicates of this one.
SUSPENDED as correctly-rounding issues are generally known to be hard to fix
and to need new implementations of functions in many cases, with detailed error
analysis and exhaustive searches for worst cases for rounding.
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* [Bug math/14759] Most functions in math.h not correctly rounded
2012-10-24 8:08 [Bug math/14759] New: Most functions in math.h not correctly rounded JoshuaHopp at web dot de
2012-10-24 12:39 ` [Bug math/14759] " jsm28 at gcc dot gnu.org
@ 2012-10-24 12:42 ` jsm28 at gcc dot gnu.org
2012-10-24 12:44 ` jsm28 at gcc dot gnu.org
` (5 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2012-10-24 12:42 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14759
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bob.wilson at acm dot org
--- Comment #2 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-10-24 12:42:06 UTC ---
*** Bug 1161 has been marked as a duplicate of this bug. ***
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* [Bug math/14759] Most functions in math.h not correctly rounded
2012-10-24 8:08 [Bug math/14759] New: Most functions in math.h not correctly rounded JoshuaHopp at web dot de
2012-10-24 12:39 ` [Bug math/14759] " jsm28 at gcc dot gnu.org
2012-10-24 12:42 ` jsm28 at gcc dot gnu.org
@ 2012-10-24 12:44 ` jsm28 at gcc dot gnu.org
2012-10-24 12:44 ` jsm28 at gcc dot gnu.org
` (4 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2012-10-24 12:44 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14759
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |hjl.tools at gmail dot com
--- Comment #4 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-10-24 12:44:26 UTC ---
*** Bug 2540 has been marked as a duplicate of this bug. ***
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* [Bug math/14759] Most functions in math.h not correctly rounded
2012-10-24 8:08 [Bug math/14759] New: Most functions in math.h not correctly rounded JoshuaHopp at web dot de
` (2 preceding siblings ...)
2012-10-24 12:44 ` jsm28 at gcc dot gnu.org
@ 2012-10-24 12:44 ` jsm28 at gcc dot gnu.org
2013-08-27 7:58 ` bagnara at cs dot unipr.it
` (3 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2012-10-24 12:44 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14759
--- Comment #3 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-10-24 12:43:43 UTC ---
*** Bug 1163 has been marked as a duplicate of this bug. ***
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* [Bug math/14759] Most functions in math.h not correctly rounded
2012-10-24 8:08 [Bug math/14759] New: Most functions in math.h not correctly rounded JoshuaHopp at web dot de
` (3 preceding siblings ...)
2012-10-24 12:44 ` jsm28 at gcc dot gnu.org
@ 2013-08-27 7:58 ` bagnara at cs dot unipr.it
2013-11-28 22:38 ` jsm28 at gcc dot gnu.org
` (2 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: bagnara at cs dot unipr.it @ 2013-08-27 7:58 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14759
Roberto Bagnara <bagnara at cs dot unipr.it> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bagnara at cs dot unipr.it
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* [Bug math/14759] Most functions in math.h not correctly rounded
2012-10-24 8:08 [Bug math/14759] New: Most functions in math.h not correctly rounded JoshuaHopp at web dot de
` (4 preceding siblings ...)
2013-08-27 7:58 ` bagnara at cs dot unipr.it
@ 2013-11-28 22:38 ` jsm28 at gcc dot gnu.org
2014-01-29 16:35 ` jsm28 at gcc dot gnu.org
2014-06-14 11:18 ` fweimer at redhat dot com
7 siblings, 0 replies; 9+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2013-11-28 22:38 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=14759
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|SUSPENDED |RESOLVED
Resolution|--- |INVALID
--- Comment #5 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
glibc accuracy goals are now documented in the manual and the FAQ and correct
rounding is explicitly excluded - without ruling out the possibility that in
future we could add correctly rounding functions under names such as crasin, or
other functions with well-defined error bounds, probably automatically
generated with tools such as metalibm.
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* [Bug math/14759] Most functions in math.h not correctly rounded
2012-10-24 8:08 [Bug math/14759] New: Most functions in math.h not correctly rounded JoshuaHopp at web dot de
` (5 preceding siblings ...)
2013-11-28 22:38 ` jsm28 at gcc dot gnu.org
@ 2014-01-29 16:35 ` jsm28 at gcc dot gnu.org
2014-06-14 11:18 ` fweimer at redhat dot com
7 siblings, 0 replies; 9+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2014-01-29 16:35 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=14759
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |zimmerma+gcc at loria dot fr
--- Comment #6 from Joseph Myers <jsm28 at gcc dot gnu.org> ---
*** Bug 16509 has been marked as a duplicate of this bug. ***
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* [Bug math/14759] Most functions in math.h not correctly rounded
2012-10-24 8:08 [Bug math/14759] New: Most functions in math.h not correctly rounded JoshuaHopp at web dot de
` (6 preceding siblings ...)
2014-01-29 16:35 ` jsm28 at gcc dot gnu.org
@ 2014-06-14 11:18 ` fweimer at redhat dot com
7 siblings, 0 replies; 9+ messages in thread
From: fweimer at redhat dot com @ 2014-06-14 11:18 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=14759
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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2012-10-24 8:08 [Bug math/14759] New: Most functions in math.h not correctly rounded JoshuaHopp at web dot de
2012-10-24 12:39 ` [Bug math/14759] " jsm28 at gcc dot gnu.org
2012-10-24 12:42 ` jsm28 at gcc dot gnu.org
2012-10-24 12:44 ` jsm28 at gcc dot gnu.org
2012-10-24 12:44 ` jsm28 at gcc dot gnu.org
2013-08-27 7:58 ` bagnara at cs dot unipr.it
2013-11-28 22:38 ` jsm28 at gcc dot gnu.org
2014-01-29 16:35 ` jsm28 at gcc dot gnu.org
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