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* [Bug math/5794] New: expm1l(x) overflows when 11356.1768 < x <= 11356.5234 @ 2008-02-26 7:04 petrosyan at gmail dot com 2008-02-26 7:09 ` [Bug math/5794] " petrosyan at gmail dot com ` (3 more replies) 0 siblings, 4 replies; 7+ messages in thread From: petrosyan at gmail dot com @ 2008-02-26 7:04 UTC (permalink / raw) To: glibc-bugs The value of (e^x - 1) is representable as a long double when x <= 11356.5234, but expm1l(x) overflows to infinity when x > 11356.1768 (approximately). Steps to Reproduce: Compile and run the following program: #include <stdio.h> #include <math.h> main () { long double a, b; const long double x = 11356.35L; a = expl (x) - 1.0L; b = expm1l (x); if (a == b) { printf ("e^%.2Lf - 1 = %Lg\n", b); return 0; } else { printf ("e^%.2Lf - 1 = %Lg; but expm1l(%.2Lf) returned %Lg\n", x, a, x, b); return 1; } } Actual Results: e^11356.35 - 1 = 1.00032e+4932; but expm1l(11356.35) returned inf Expected Results: e^11356.35 - 1 = 1.00032e+4932 Additional info: This bug probably isn't even worth reporting, except for completeness. expm1l is designed to compute e^x-1 more accurately when x is negative, so [at least the i386 version] uses a slightly different algorithm than expl. This algorithm overflows for large x where expl would not. But then, expm1 really isn't intended for large x anyway. In my own port of the math library, I circumvent the problem by calling __ieee754_expl when x >= 64, because at that magnitude, -1 is too small to affect the result. This is probably overkill, but it works. -- Summary: expm1l(x) overflows when 11356.1768 < x <= 11356.5234 Product: glibc Version: unspecified Status: NEW Severity: minor Priority: P2 Component: math AssignedTo: aj at suse dot de ReportedBy: petrosyan at gmail dot com CC: glibc-bugs at sources dot redhat dot com http://sourceware.org/bugzilla/show_bug.cgi?id=5794 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug math/5794] expm1l(x) overflows when 11356.1768 < x <= 11356.5234 2008-02-26 7:04 [Bug math/5794] New: expm1l(x) overflows when 11356.1768 < x <= 11356.5234 petrosyan at gmail dot com @ 2008-02-26 7:09 ` petrosyan at gmail dot com 2008-02-26 7:09 ` petrosyan at gmail dot com ` (2 subsequent siblings) 3 siblings, 0 replies; 7+ messages in thread From: petrosyan at gmail dot com @ 2008-02-26 7:09 UTC (permalink / raw) To: glibc-bugs ------- Additional Comments From petrosyan at gmail dot com 2008-02-26 07:08 ------- original bug filed at https://bugzilla.redhat.com/show_bug.cgi?id=43354 -- What |Removed |Added ---------------------------------------------------------------------------- Version|unspecified |2.2.5 http://sourceware.org/bugzilla/show_bug.cgi?id=5794 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug math/5794] expm1l(x) overflows when 11356.1768 < x <= 11356.5234 2008-02-26 7:04 [Bug math/5794] New: expm1l(x) overflows when 11356.1768 < x <= 11356.5234 petrosyan at gmail dot com 2008-02-26 7:09 ` [Bug math/5794] " petrosyan at gmail dot com @ 2008-02-26 7:09 ` petrosyan at gmail dot com 2008-07-30 10:08 ` vda dot linux at googlemail dot com 2008-08-05 22:11 ` drepper at redhat dot com 3 siblings, 0 replies; 7+ messages in thread From: petrosyan at gmail dot com @ 2008-02-26 7:09 UTC (permalink / raw) To: glibc-bugs -- What |Removed |Added ---------------------------------------------------------------------------- Version|2.2.5 |unspecified http://sourceware.org/bugzilla/show_bug.cgi?id=5794 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug math/5794] expm1l(x) overflows when 11356.1768 < x <= 11356.5234 2008-02-26 7:04 [Bug math/5794] New: expm1l(x) overflows when 11356.1768 < x <= 11356.5234 petrosyan at gmail dot com 2008-02-26 7:09 ` [Bug math/5794] " petrosyan at gmail dot com 2008-02-26 7:09 ` petrosyan at gmail dot com @ 2008-07-30 10:08 ` vda dot linux at googlemail dot com 2008-08-05 22:11 ` drepper at redhat dot com 3 siblings, 0 replies; 7+ messages in thread From: vda dot linux at googlemail dot com @ 2008-07-30 10:08 UTC (permalink / raw) To: glibc-bugs ------- Additional Comments From vda dot linux at googlemail dot com 2008-07-30 10:07 ------- I submitted a fix, see RH bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=43354 -- http://sourceware.org/bugzilla/show_bug.cgi?id=5794 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug math/5794] expm1l(x) overflows when 11356.1768 < x <= 11356.5234 2008-02-26 7:04 [Bug math/5794] New: expm1l(x) overflows when 11356.1768 < x <= 11356.5234 petrosyan at gmail dot com ` (2 preceding siblings ...) 2008-07-30 10:08 ` vda dot linux at googlemail dot com @ 2008-08-05 22:11 ` drepper at redhat dot com 3 siblings, 0 replies; 7+ messages in thread From: drepper at redhat dot com @ 2008-08-05 22:11 UTC (permalink / raw) To: glibc-bugs ------- Additional Comments From drepper at redhat dot com 2008-08-05 22:09 ------- Fixed in cvs. -- http://sourceware.org/bugzilla/show_bug.cgi?id=5794 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is. ^ permalink raw reply [flat|nested] 7+ messages in thread
[parent not found: <bug-5794-131@http.sourceware.org/bugzilla/>]
* [Bug math/5794] expm1l(x) overflows when 11356.1768 < x <= 11356.5234 [not found] <bug-5794-131@http.sourceware.org/bugzilla/> @ 2012-02-29 17:49 ` jsm28 at gcc dot gnu.org 2014-07-02 7:02 ` fweimer at redhat dot com 1 sibling, 0 replies; 7+ messages in thread From: jsm28 at gcc dot gnu.org @ 2012-02-29 17:49 UTC (permalink / raw) To: glibc-bugs http://sourceware.org/bugzilla/show_bug.cgi?id=5794 Joseph Myers <jsm28 at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |FIXED --- Comment #4 from Joseph Myers <jsm28 at gcc dot gnu.org> 2012-02-29 17:49:28 UTC --- This was fixed by: 2008-08-05 Ulrich Drepper <drepper@redhat.com> [BZ #5794] * sysdeps/i386/fpu/s_expm1l.S: Simply use exp implementation for large parameters. * sysdeps/x86_64/fpu/s_expm1l.S: Likewise. Patch by Denys Vlasenko <dvlasenk@redhat.com>. A testcase wasn't added to the testsuite at the time. I've now proposed adding one: http://sourceware.org/ml/libc-alpha/2012-02/msg00773.html -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug math/5794] expm1l(x) overflows when 11356.1768 < x <= 11356.5234 [not found] <bug-5794-131@http.sourceware.org/bugzilla/> 2012-02-29 17:49 ` jsm28 at gcc dot gnu.org @ 2014-07-02 7:02 ` fweimer at redhat dot com 1 sibling, 0 replies; 7+ messages in thread From: fweimer at redhat dot com @ 2014-07-02 7:02 UTC (permalink / raw) To: glibc-bugs https://sourceware.org/bugzilla/show_bug.cgi?id=5794 Florian Weimer <fweimer at redhat dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Flags| |security- -- You are receiving this mail because: You are on the CC list for the bug. ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2014-07-02 7:02 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2008-02-26 7:04 [Bug math/5794] New: expm1l(x) overflows when 11356.1768 < x <= 11356.5234 petrosyan at gmail dot com 2008-02-26 7:09 ` [Bug math/5794] " petrosyan at gmail dot com 2008-02-26 7:09 ` petrosyan at gmail dot com 2008-07-30 10:08 ` vda dot linux at googlemail dot com 2008-08-05 22:11 ` drepper at redhat dot com [not found] <bug-5794-131@http.sourceware.org/bugzilla/> 2012-02-29 17:49 ` jsm28 at gcc dot gnu.org 2014-07-02 7:02 ` fweimer at redhat dot com
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