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* [Bug math/14472] New: Inaccurate y1f function on x86_32
@ 2012-08-15 14:18 liubov.dmitrieva at gmail dot com
2012-08-15 14:31 ` [Bug math/14472] " liubov.dmitrieva at gmail dot com
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: liubov.dmitrieva at gmail dot com @ 2012-08-15 14:18 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14472
Bug #: 14472
Summary: Inaccurate y1f function on x86_32
Product: glibc
Version: 2.17
Status: NEW
Severity: normal
Priority: P2
Component: math
AssignedTo: unassigned@sourceware.org
ReportedBy: liubov.dmitrieva@gmail.com
Classification: Unclassified
// gcc main.c -std=c99 -lm -m32
#include <stdio.h>
#include <fenv.h>
#include <stdlib.h> // abs function for int argument
extern float y1f(float);
extern double y1(double);
#define i32(a) (((int*)&(a))[0])
int main() {
float a,r1,r2;
i32(a)=0x422cc0bc; //argument
fesetround(FE_TONEAREST); // FE_TONEAREST
r1 = y1f(a); //actual result
r2 = y1(a); //actual result 2
printf("inputs: a = (0x%08x)\t%e\n", i32(a), a);
printf("actual = (0x%08x)\t%.13e\n", i32(r1), r1);
printf("expected = (0x%08x)\t%.13e\n", i32(r2), r2);
printf("error = %d ulp\n", abs(i32(r1) - i32(r2)));
return 0;
}
Result:
inputs: a = (0x422cc0bc) 4.318822e+01
actual = (0x33f3b02b) 1.1347614048418e-07
expected = (0x33f3934c) 1.1342362427058e-07
error = 7391 ulp
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* [Bug math/14472] Inaccurate y1f function on x86_32
2012-08-15 14:18 [Bug math/14472] New: Inaccurate y1f function on x86_32 liubov.dmitrieva at gmail dot com
@ 2012-08-15 14:31 ` liubov.dmitrieva at gmail dot com
2012-08-15 14:43 ` [Bug math/14472] Inaccurate y1f function on x86_32 and x86_64 liubov.dmitrieva at gmail dot com
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: liubov.dmitrieva at gmail dot com @ 2012-08-15 14:31 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14472
--- Comment #1 from Liubov Dmitrieva <liubov.dmitrieva at gmail dot com> 2012-08-15 14:31:17 UTC ---
The same test case shows bad accuracy for x86_64 as well:
(core2 machine)
-bash-4.2$ gcc main_y1f.c -lm -odo
-bash-4.2$ ./do
inputs: a = (0x422cc0bc) 4.318822e+01
actual = (0x33f3a4bd) 1.1345535000373e-07
expected = (0x33f3934c) 1.1342362427058e-07
error = 4465 ulp
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* [Bug math/14472] Inaccurate y1f function on x86_32 and x86_64
2012-08-15 14:18 [Bug math/14472] New: Inaccurate y1f function on x86_32 liubov.dmitrieva at gmail dot com
2012-08-15 14:31 ` [Bug math/14472] " liubov.dmitrieva at gmail dot com
@ 2012-08-15 14:43 ` liubov.dmitrieva at gmail dot com
2012-08-16 8:23 ` liubov.dmitrieva at gmail dot com
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: liubov.dmitrieva at gmail dot com @ 2012-08-15 14:43 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14472
Liubov Dmitrieva <liubov.dmitrieva at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|Inaccurate y1f function on |Inaccurate y1f function on
|x86_32 |x86_32 and x86_64
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* [Bug math/14472] Inaccurate y1f function on x86_32 and x86_64
2012-08-15 14:18 [Bug math/14472] New: Inaccurate y1f function on x86_32 liubov.dmitrieva at gmail dot com
2012-08-15 14:31 ` [Bug math/14472] " liubov.dmitrieva at gmail dot com
2012-08-15 14:43 ` [Bug math/14472] Inaccurate y1f function on x86_32 and x86_64 liubov.dmitrieva at gmail dot com
@ 2012-08-16 8:23 ` liubov.dmitrieva at gmail dot com
2014-02-06 18:32 ` [Bug math/14472] Inaccurate y1f function jsm28 at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: liubov.dmitrieva at gmail dot com @ 2012-08-16 8:23 UTC (permalink / raw)
To: glibc-bugs
http://sourceware.org/bugzilla/show_bug.cgi?id=14472
--- Comment #2 from Liubov Dmitrieva <liubov.dmitrieva at gmail dot com> 2012-08-16 08:23:12 UTC ---
>> represent the test argument using a hex float value
Updated test:
#include <stdio.h>
#include <math.h>
#include <fenv.h>
extern float y1f(float);
extern double y1(double);
int main() {
float a,r1;
double r2;
a=0x1.598178p5; //argument
fesetround(FE_TONEAREST);
r1 = y1f(a); //actual result
r2 = y1(a); //actual result 2
printf("inputs: a = %.6a\n", a);
printf("actual = %.6a\n", r1);
printf("expected = %.6a\n", r2);
printf("error = %f ulp\n", fabs(r1 - r2) * exp2(23.0-logbf(r1)));
return 0;
}
Result x86:
inputs: a = 0x1.598178p+5
actual = 0x1.e76056p-24
expected = 0x1.e72698p-24
error = 7390.926985 ulp
Result x86_64:
inputs: a = 0x1.598178p+5
actual = 0x1.e7497ap-24
expected = 0x1.e72698p-24
error = 4464.927009 ulp
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* [Bug math/14472] Inaccurate y1f function
2012-08-15 14:18 [Bug math/14472] New: Inaccurate y1f function on x86_32 liubov.dmitrieva at gmail dot com
` (2 preceding siblings ...)
2012-08-16 8:23 ` liubov.dmitrieva at gmail dot com
@ 2014-02-06 18:32 ` jsm28 at gcc dot gnu.org
2014-06-17 18:38 ` fweimer at redhat dot com
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: jsm28 at gcc dot gnu.org @ 2014-02-06 18:32 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=14472
Joseph Myers <jsm28 at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|Inaccurate y1f function on |Inaccurate y1f function
|x86_32 and x86_64 |
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* [Bug math/14472] Inaccurate y1f function
2012-08-15 14:18 [Bug math/14472] New: Inaccurate y1f function on x86_32 liubov.dmitrieva at gmail dot com
` (3 preceding siblings ...)
2014-02-06 18:32 ` [Bug math/14472] Inaccurate y1f function jsm28 at gcc dot gnu.org
@ 2014-06-17 18:38 ` fweimer at redhat dot com
2020-08-06 10:58 ` zimmerma+gcc at loria dot fr
2021-04-02 4:25 ` zimmerma+gcc at loria dot fr
6 siblings, 0 replies; 8+ messages in thread
From: fweimer at redhat dot com @ 2014-06-17 18:38 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=14472
Florian Weimer <fweimer at redhat dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Flags| |security-
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* [Bug math/14472] Inaccurate y1f function
2012-08-15 14:18 [Bug math/14472] New: Inaccurate y1f function on x86_32 liubov.dmitrieva at gmail dot com
` (4 preceding siblings ...)
2014-06-17 18:38 ` fweimer at redhat dot com
@ 2020-08-06 10:58 ` zimmerma+gcc at loria dot fr
2021-04-02 4:25 ` zimmerma+gcc at loria dot fr
6 siblings, 0 replies; 8+ messages in thread
From: zimmerma+gcc at loria dot fr @ 2020-08-06 10:58 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=14472
--- Comment #4 from Paul Zimmermann <zimmerma+gcc at loria dot fr> ---
with glibc-2.32 the maximum error on x86_64 is now 6177902 ulps (for
x=3.153646966e+38). This is the same value where the maximal error is obtained
for j0. This is not surprising since y1(x) ~ -j0(x) for large x, probably the
same code is used (I did not check).
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* [Bug math/14472] Inaccurate y1f function
2012-08-15 14:18 [Bug math/14472] New: Inaccurate y1f function on x86_32 liubov.dmitrieva at gmail dot com
` (5 preceding siblings ...)
2020-08-06 10:58 ` zimmerma+gcc at loria dot fr
@ 2021-04-02 4:25 ` zimmerma+gcc at loria dot fr
6 siblings, 0 replies; 8+ messages in thread
From: zimmerma+gcc at loria dot fr @ 2021-04-02 4:25 UTC (permalink / raw)
To: glibc-bugs
https://sourceware.org/bugzilla/show_bug.cgi?id=14472
Paul Zimmermann <zimmerma+gcc at loria dot fr> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Target Milestone|--- |2.34
Resolution|--- |FIXED
--- Comment #5 from Paul Zimmermann <zimmerma+gcc at loria dot fr> ---
fixed by commit 9acda61
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2012-08-15 14:18 [Bug math/14472] New: Inaccurate y1f function on x86_32 liubov.dmitrieva at gmail dot com
2012-08-15 14:31 ` [Bug math/14472] " liubov.dmitrieva at gmail dot com
2012-08-15 14:43 ` [Bug math/14472] Inaccurate y1f function on x86_32 and x86_64 liubov.dmitrieva at gmail dot com
2012-08-16 8:23 ` liubov.dmitrieva at gmail dot com
2014-02-06 18:32 ` [Bug math/14472] Inaccurate y1f function jsm28 at gcc dot gnu.org
2014-06-17 18:38 ` fweimer at redhat dot com
2020-08-06 10:58 ` zimmerma+gcc at loria dot fr
2021-04-02 4:25 ` zimmerma+gcc at loria dot fr
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