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* [Bug math/2678] pow returns incorrect results on underflow
[not found] <bug-2678-131@http.sourceware.org/bugzilla/>
@ 2012-02-28 16:41 ` jsm28 at gcc dot gnu.org
2012-03-28 15:05 ` jsm28 at gcc dot gnu.org
1 sibling, 0 replies; 9+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2012-02-28 16:41 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=2678
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|aj at suse dot de |unassigned at sourceware
| |dot org
--- Comment #6 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-02-28 16:40:27 UTC ---
Confirmed still present.
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* [Bug math/2678] pow returns incorrect results on underflow
[not found] <bug-2678-131@http.sourceware.org/bugzilla/>
2012-02-28 16:41 ` [Bug math/2678] pow returns incorrect results on underflow jsm28 at gcc dot gnu.org
@ 2012-03-28 15:05 ` jsm28 at gcc dot gnu.org
1 sibling, 0 replies; 9+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2012-03-28 15:05 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=2678
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
--- Comment #7 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-03-28 15:03:05 UTC ---
Fixed by:
commit d6270972f79fe89a96fa7a3909991dad2e317033
Author: Joseph Myers <joseph@codesourcery.com>
Date: Wed Mar 28 14:57:58 2012 +0000
Fix pow of negative numbers to integer exponents (bugs 369, 2678, 3866).
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* [Bug math/2678] pow returns incorrect results on underflow
2006-05-21 0:30 [Bug math/2678] New: " jsm28 at gcc dot gnu dot org
` (5 preceding siblings ...)
2009-09-24 10:43 ` vincent+libc at vinc17 dot org
@ 2009-09-24 14:06 ` zimmerma+gcc at loria dot fr
6 siblings, 0 replies; 9+ messages in thread
From: zimmerma+gcc at loria dot fr @ 2009-09-24 14:06 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From zimmerma+gcc at loria dot fr 2009-09-24 14:06 -------
(In reply to comment #4)
> It seems that constant folding on pow() isn't done by GCC yet.
according to http://gcc.gnu.org/gcc-4.3/changes.html#mpfropts, pow is also
handled by the constant folding mechanism.
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* [Bug math/2678] pow returns incorrect results on underflow
2006-05-21 0:30 [Bug math/2678] New: " jsm28 at gcc dot gnu dot org
` (4 preceding siblings ...)
2009-09-24 9:44 ` zimmerma+gcc at loria dot fr
@ 2009-09-24 10:43 ` vincent+libc at vinc17 dot org
2009-09-24 14:06 ` zimmerma+gcc at loria dot fr
6 siblings, 0 replies; 9+ messages in thread
From: vincent+libc at vinc17 dot org @ 2009-09-24 10:43 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From vincent+libc at vinc17 dot org 2009-09-24 10:43 -------
(In reply to comment #3)
> Moreover when compiling with -O1 with GCC 4.3.2 (i.e., when constant folding
> is activated)
It seems that constant folding on pow() isn't done by GCC yet. I interpret the
change due to -O1 by an optimization like pow(x,3) -> x * x * x (and glibc isn't
concerned since this is a GCC optimization).
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* [Bug math/2678] pow returns incorrect results on underflow
2006-05-21 0:30 [Bug math/2678] New: " jsm28 at gcc dot gnu dot org
` (3 preceding siblings ...)
2009-09-24 9:43 ` zimmerma+gcc at loria dot fr
@ 2009-09-24 9:44 ` zimmerma+gcc at loria dot fr
2009-09-24 10:43 ` vincent+libc at vinc17 dot org
2009-09-24 14:06 ` zimmerma+gcc at loria dot fr
6 siblings, 0 replies; 9+ messages in thread
From: zimmerma+gcc at loria dot fr @ 2009-09-24 9:44 UTC (permalink / raw)
To: glibc-bugs
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CC| |zimmerma+gcc at loria dot fr
http://sourceware.org/bugzilla/show_bug.cgi?id=2678
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* [Bug math/2678] pow returns incorrect results on underflow
2006-05-21 0:30 [Bug math/2678] New: " jsm28 at gcc dot gnu dot org
` (2 preceding siblings ...)
2009-09-24 9:42 ` zimmerma+gcc at loria dot fr
@ 2009-09-24 9:43 ` zimmerma+gcc at loria dot fr
2009-09-24 9:44 ` zimmerma+gcc at loria dot fr
` (2 subsequent siblings)
6 siblings, 0 replies; 9+ messages in thread
From: zimmerma+gcc at loria dot fr @ 2009-09-24 9:43 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From zimmerma+gcc at loria dot fr 2009-09-24 09:43 -------
This is still wrong with glibc 2.9, and with 2.10.1 (development version):
pow(-2.225074e-308,3.000000e+00) = 0.000000 (-0 expected) [mpfr -0.000000]
pow(-2.225074e-308,1.677722e+07) = 0.000000 (-0 expected) [mpfr -0.000000]
pow(-2.225074e-308,1.000000e+10) = 0.000000 (0 expected) [mpfr 0.000000]
pow(-2.225074e-308,1.000000e+20) = 0.000000 (0 expected) [mpfr 0.000000]
pow(-1.797693e+308,-3.000000e+00) = 0.000000 (-0 expected) [mpfr -0.000000]
pow(-1.797693e+308,-1.677722e+07) = 0.000000 (-0 expected) [mpfr -0.000000]
pow(-1.797693e+308,-1.000000e+10) = 0.000000 (0 expected) [mpfr 0.000000]
pow(-1.797693e+308,-1.000000e+20) = 0.000000 (0 expected) [mpfr 0.000000]
Moreover when compiling with -O1 with GCC 4.3.2 (i.e., when constant folding is
activated) all tests except the first one are wrong too (but the values computed
by MPFR are correct):
libc version: 2.10.1
pow(-2.225074e-308,3.000000e+00) = -0.000000 (-0 expected) [mpfr -0.000000]
pow(-2.225074e-308,1.677722e+07) = 0.000000 (-0 expected) [mpfr -0.000000]
pow(-2.225074e-308,1.000000e+10) = 0.000000 (0 expected) [mpfr 0.000000]
pow(-2.225074e-308,1.000000e+20) = 0.000000 (0 expected) [mpfr 0.000000]
pow(-1.797693e+308,-3.000000e+00) = 0.000000 (-0 expected) [mpfr -0.000000]
pow(-1.797693e+308,-1.677722e+07) = 0.000000 (-0 expected) [mpfr -0.000000]
pow(-1.797693e+308,-1.000000e+10) = 0.000000 (0 expected) [mpfr 0.000000]
pow(-1.797693e+308,-1.000000e+20) = 0.000000 (0 expected) [mpfr 0.000000]
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* [Bug math/2678] pow returns incorrect results on underflow
2006-05-21 0:30 [Bug math/2678] New: " jsm28 at gcc dot gnu dot org
2006-05-21 0:31 ` [Bug math/2678] " jsm28 at gcc dot gnu dot org
2009-09-24 8:09 ` vincent+libc at vinc17 dot org
@ 2009-09-24 9:42 ` zimmerma+gcc at loria dot fr
2009-09-24 9:43 ` zimmerma+gcc at loria dot fr
` (3 subsequent siblings)
6 siblings, 0 replies; 9+ messages in thread
From: zimmerma+gcc at loria dot fr @ 2009-09-24 9:42 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From zimmerma+gcc at loria dot fr 2009-09-24 09:42 -------
Created an attachment (id=4227)
--> (http://sourceware.org/bugzilla/attachment.cgi?id=4227&action=view)
test case
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* [Bug math/2678] pow returns incorrect results on underflow
2006-05-21 0:30 [Bug math/2678] New: " jsm28 at gcc dot gnu dot org
2006-05-21 0:31 ` [Bug math/2678] " jsm28 at gcc dot gnu dot org
@ 2009-09-24 8:09 ` vincent+libc at vinc17 dot org
2009-09-24 9:42 ` zimmerma+gcc at loria dot fr
` (4 subsequent siblings)
6 siblings, 0 replies; 9+ messages in thread
From: vincent+libc at vinc17 dot org @ 2009-09-24 8:09 UTC (permalink / raw)
To: glibc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
CC| |vincent+libc at vinc17 dot
| |org
http://sourceware.org/bugzilla/show_bug.cgi?id=2678
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* [Bug math/2678] pow returns incorrect results on underflow
2006-05-21 0:30 [Bug math/2678] New: " jsm28 at gcc dot gnu dot org
@ 2006-05-21 0:31 ` jsm28 at gcc dot gnu dot org
2009-09-24 8:09 ` vincent+libc at vinc17 dot org
` (5 subsequent siblings)
6 siblings, 0 replies; 9+ messages in thread
From: jsm28 at gcc dot gnu dot org @ 2006-05-21 0:31 UTC (permalink / raw)
To: glibc-bugs
------- Additional Comments From jsm28 at gcc dot gnu dot org 2006-05-21 00:31 -------
Created an attachment (id=1035)
--> (http://sourceware.org/bugzilla/attachment.cgi?id=1035&action=view)
Testsuite patch
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[not found] <bug-2678-131@http.sourceware.org/bugzilla/>
2012-02-28 16:41 ` [Bug math/2678] pow returns incorrect results on underflow jsm28 at gcc dot gnu.org
2012-03-28 15:05 ` jsm28 at gcc dot gnu.org
2006-05-21 0:30 [Bug math/2678] New: " jsm28 at gcc dot gnu dot org
2006-05-21 0:31 ` [Bug math/2678] " jsm28 at gcc dot gnu dot org
2009-09-24 8:09 ` vincent+libc at vinc17 dot org
2009-09-24 9:42 ` zimmerma+gcc at loria dot fr
2009-09-24 9:43 ` zimmerma+gcc at loria dot fr
2009-09-24 9:44 ` zimmerma+gcc at loria dot fr
2009-09-24 10:43 ` vincent+libc at vinc17 dot org
2009-09-24 14:06 ` zimmerma+gcc at loria dot fr
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