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* [Bug math/15734] New: IBM long double erfl and erfcl very inaccurate
@ 2013-07-12 14:44 amodra at gmail dot com
2013-07-12 14:45 ` [Bug math/15734] " amodra at gmail dot com
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: amodra at gmail dot com @ 2013-07-12 14:44 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=15734
Bug ID: 15734
Summary: IBM long double erfl and erfcl very inaccurate
Product: glibc
Version: 2.18
Status: NEW
Severity: normal
Priority: P2
Component: math
Assignee: unassigned at sourceware dot org
Reporter: amodra at gmail dot com
The IBM long double implementation of erfl() and erfcl() both give inaccurate
results when given a negative argument such that the component doubles have
differing sign. Also, erfl() with a large negative argument returns +1.0
rather than -1.0.
The following compiled with -O0 shows one such bad result. (Compare with
results from -O2 where gcc evalates erfl and erfl.)
#include <stdio.h>
#include <math.h>
int
main (void)
{
long double x, z;
union { long double ld; double d[2]; } u;
x = -0x1.fffffffffffff8p-2L;
z = erfl (x);
u.ld = x;
printf ("%24.21Lf %36La %21a %21a\n", u.ld, u.ld, u.d[0], u.d[1]);
u.ld = z;
printf ("%24.21Lf %36La %21a %21a\n", u.ld, u.ld, u.d[0], u.d[1]);
z = erfcl (x);
u.ld = z;
printf ("%24.21Lf %36La %21a %21a\n", u.ld, u.ld, u.d[0], u.d[1]);
return 0;
}
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* [Bug math/15734] IBM long double erfl and erfcl very inaccurate
2013-07-12 14:44 [Bug math/15734] New: IBM long double erfl and erfcl very inaccurate amodra at gmail dot com
@ 2013-07-12 14:45 ` amodra at gmail dot com
2013-10-05 3:00 ` amodra at gmail dot com
2014-06-13 9:25 ` fweimer at redhat dot com
2 siblings, 0 replies; 4+ messages in thread
From: amodra at gmail dot com @ 2013-07-12 14:45 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=15734
Alan Modra <amodra at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at sourceware dot org |amodra at gmail dot com
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* [Bug math/15734] IBM long double erfl and erfcl very inaccurate
2013-07-12 14:44 [Bug math/15734] New: IBM long double erfl and erfcl very inaccurate amodra at gmail dot com
2013-07-12 14:45 ` [Bug math/15734] " amodra at gmail dot com
@ 2013-10-05 3:00 ` amodra at gmail dot com
2014-06-13 9:25 ` fweimer at redhat dot com
2 siblings, 0 replies; 4+ messages in thread
From: amodra at gmail dot com @ 2013-10-05 3:00 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=15734
Alan Modra <amodra at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
URL| |http://sourceware.org/ml/li
| |bc-alpha/2013-08/msg00084.h
| |tml
Resolution|--- |FIXED
Target Milestone|--- |2.19
--- Comment #1 from Alan Modra <amodra at gmail dot com> ---
Fixed
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* [Bug math/15734] IBM long double erfl and erfcl very inaccurate
2013-07-12 14:44 [Bug math/15734] New: IBM long double erfl and erfcl very inaccurate amodra at gmail dot com
2013-07-12 14:45 ` [Bug math/15734] " amodra at gmail dot com
2013-10-05 3:00 ` amodra at gmail dot com
@ 2014-06-13 9:25 ` fweimer at redhat dot com
2 siblings, 0 replies; 4+ messages in thread
From: fweimer at redhat dot com @ 2014-06-13 9:25 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=15734
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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end of thread, other threads:[~2014-06-13 9:25 UTC | newest]
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2013-07-12 14:44 [Bug math/15734] New: IBM long double erfl and erfcl very inaccurate amodra at gmail dot com
2013-07-12 14:45 ` [Bug math/15734] " amodra at gmail dot com
2013-10-05 3:00 ` amodra at gmail dot com
2014-06-13 9:25 ` fweimer at redhat dot com
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