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* [Bug libfortran/49024] New: REAL*16 ERFC_SCALED inaccuracy
@ 2011-05-17 14:28 thenlich at users dot sourceforge.net
2011-05-23 11:01 ` [Bug libfortran/49024] " fxcoudert at gcc dot gnu.org
` (7 more replies)
0 siblings, 8 replies; 9+ messages in thread
From: thenlich at users dot sourceforge.net @ 2011-05-17 14:28 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49024
Summary: REAL*16 ERFC_SCALED inaccuracy
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libfortran
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: thenlich@users.sourceforge.net
The libfortran implementation of the ERFC_SCALED intrinsic function is not
accurate enough to be useful for REAL*16 arithmetics.
program test_erfc_scaled
real(16), parameter :: p16 = 1.0_16
real(16) :: v16 = p16
print *, erfc_scaled(v16)
print *, erfc_scaled(p16)
print *, erfc(v16) * exp(v16 * v16)
end program test_erfc_scaled
==>
0.427583576155807003967191251980322016
0.427583576155807004410750344490515188
0.427583576155807004410750344490515140
This should be easy to fix by adding an erfc_scaled() function to libquadmath.
In fact, the error function code in libquadmath is based on the same code as
http://www.netlib.org/cephes/128bdoc.html and the latter already contains a
separate function for a scaled error function. In libquadmath it has been
merged into one (or maybe the other was split later).
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug libfortran/49024] REAL*16 ERFC_SCALED inaccuracy
2011-05-17 14:28 [Bug libfortran/49024] New: REAL*16 ERFC_SCALED inaccuracy thenlich at users dot sourceforge.net
@ 2011-05-23 11:01 ` fxcoudert at gcc dot gnu.org
2011-05-23 20:54 ` fxcoudert at gcc dot gnu.org
` (6 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: fxcoudert at gcc dot gnu.org @ 2011-05-23 11:01 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49024
Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2011.05.23 10:34:35
CC| |fxcoudert at gcc dot
| |gnu.org
AssignedTo|unassigned at gcc dot |fxcoudert at gcc dot
|gnu.org |gnu.org
Ever Confirmed|0 |1
--- Comment #1 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> 2011-05-23 10:34:35 UTC ---
I'll take that one, thanks for the report.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug libfortran/49024] REAL*16 ERFC_SCALED inaccuracy
2011-05-17 14:28 [Bug libfortran/49024] New: REAL*16 ERFC_SCALED inaccuracy thenlich at users dot sourceforge.net
2011-05-23 11:01 ` [Bug libfortran/49024] " fxcoudert at gcc dot gnu.org
@ 2011-05-23 20:54 ` fxcoudert at gcc dot gnu.org
2011-05-23 21:45 ` burnus at gcc dot gnu.org
` (5 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: fxcoudert at gcc dot gnu.org @ 2011-05-23 20:54 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49024
--- Comment #2 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> 2011-05-23 19:53:31 UTC ---
The 128-bit code for scaled erfc in Cephes is terrible. For ERFC_SCALED(1), it
gives:
0.427592...
instead of:
0.427583...
I don't see any easy way about this, someone will have to play minimax :)
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug libfortran/49024] REAL*16 ERFC_SCALED inaccuracy
2011-05-17 14:28 [Bug libfortran/49024] New: REAL*16 ERFC_SCALED inaccuracy thenlich at users dot sourceforge.net
2011-05-23 11:01 ` [Bug libfortran/49024] " fxcoudert at gcc dot gnu.org
2011-05-23 20:54 ` fxcoudert at gcc dot gnu.org
@ 2011-05-23 21:45 ` burnus at gcc dot gnu.org
2011-05-23 22:12 ` fxcoudert at gcc dot gnu.org
` (4 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: burnus at gcc dot gnu.org @ 2011-05-23 21:45 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49024
Tobias Burnus <burnus at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |burnus at gcc dot gnu.org
--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-05-23 21:20:46 UTC ---
(In reply to comment #2)
> The 128-bit code for scaled erfc in Cephes is terrible. [...]
For 128 bits: do you plan to handle it in libgfortran or directly in
libquadmath? I think one can export another function directly in libquadmath,
which should be easier to handle - and yield faster code.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug libfortran/49024] REAL*16 ERFC_SCALED inaccuracy
2011-05-17 14:28 [Bug libfortran/49024] New: REAL*16 ERFC_SCALED inaccuracy thenlich at users dot sourceforge.net
` (2 preceding siblings ...)
2011-05-23 21:45 ` burnus at gcc dot gnu.org
@ 2011-05-23 22:12 ` fxcoudert at gcc dot gnu.org
2013-11-20 22:19 ` fxcoudert at gcc dot gnu.org
` (3 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: fxcoudert at gcc dot gnu.org @ 2011-05-23 22:12 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49024
Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|fxcoudert at gcc dot |unassigned at gcc dot
|gnu.org |gnu.org
--- Comment #4 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> 2011-05-23 21:48:42 UTC ---
(In reply to comment #3)
> For 128 bits: do you plan to handle it in libgfortran or directly in
> libquadmath? I think one can export another function directly in libquadmath,
> which should be easier to handle - and yield faster code.
I've thought about it a bit, both are fine with me. But… I don't have time to
play with Mathematica right now to find the good approximations in each
possible range, so I'll unassign myself.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug libfortran/49024] REAL*16 ERFC_SCALED inaccuracy
2011-05-17 14:28 [Bug libfortran/49024] New: REAL*16 ERFC_SCALED inaccuracy thenlich at users dot sourceforge.net
` (3 preceding siblings ...)
2011-05-23 22:12 ` fxcoudert at gcc dot gnu.org
@ 2013-11-20 22:19 ` fxcoudert at gcc dot gnu.org
2013-11-21 8:46 ` fxcoudert at gcc dot gnu.org
` (2 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: fxcoudert at gcc dot gnu.org @ 2013-11-20 22:19 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49024
--- Comment #5 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> ---
Author: fxcoudert
Date: Wed Nov 20 22:18:55 2013
New Revision: 205151
URL: http://gcc.gnu.org/viewcvs?rev=205151&root=gcc&view=rev
Log:
PR libfortran/49024
* intrinsics/erfc_scaled.c (erfc_scaled_r16): New function.
* intrinsics/erfc_scaled_inc.c: Do not provide quadruple
precision variant.
* gfortran.dg/erf_3.F90: New file.
Added:
trunk/gcc/testsuite/gfortran.dg/erf_3.F90
Modified:
trunk/gcc/testsuite/ChangeLog
trunk/libgfortran/ChangeLog
trunk/libgfortran/intrinsics/erfc_scaled.c
trunk/libgfortran/intrinsics/erfc_scaled_inc.c
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug libfortran/49024] REAL*16 ERFC_SCALED inaccuracy
2011-05-17 14:28 [Bug libfortran/49024] New: REAL*16 ERFC_SCALED inaccuracy thenlich at users dot sourceforge.net
` (5 preceding siblings ...)
2013-11-21 8:46 ` fxcoudert at gcc dot gnu.org
@ 2013-11-21 8:46 ` fxcoudert at gcc dot gnu.org
2013-11-21 9:21 ` schwab@linux-m68k.org
7 siblings, 0 replies; 9+ messages in thread
From: fxcoudert at gcc dot gnu.org @ 2013-11-21 8:46 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49024
Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #6 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> ---
Fixed on trunk.
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug libfortran/49024] REAL*16 ERFC_SCALED inaccuracy
2011-05-17 14:28 [Bug libfortran/49024] New: REAL*16 ERFC_SCALED inaccuracy thenlich at users dot sourceforge.net
` (4 preceding siblings ...)
2013-11-20 22:19 ` fxcoudert at gcc dot gnu.org
@ 2013-11-21 8:46 ` fxcoudert at gcc dot gnu.org
2013-11-21 8:46 ` fxcoudert at gcc dot gnu.org
2013-11-21 9:21 ` schwab@linux-m68k.org
7 siblings, 0 replies; 9+ messages in thread
From: fxcoudert at gcc dot gnu.org @ 2013-11-21 8:46 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49024
Bug 49024 depends on bug 59227, which changed state.
Bug 59227 Summary: [4.9 regression] FAIL: gfortran.dg/erf_3.F90 -O0 execution test
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59227
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution|--- |FIXED
^ permalink raw reply [flat|nested] 9+ messages in thread
* [Bug libfortran/49024] REAL*16 ERFC_SCALED inaccuracy
2011-05-17 14:28 [Bug libfortran/49024] New: REAL*16 ERFC_SCALED inaccuracy thenlich at users dot sourceforge.net
` (6 preceding siblings ...)
2013-11-21 8:46 ` fxcoudert at gcc dot gnu.org
@ 2013-11-21 9:21 ` schwab@linux-m68k.org
7 siblings, 0 replies; 9+ messages in thread
From: schwab@linux-m68k.org @ 2013-11-21 9:21 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49024
Bug 49024 depends on bug 59227, which changed state.
Bug 59227 Summary: [4.9 regression] FAIL: gfortran.dg/erf_3.F90 -O0 execution test
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59227
What |Removed |Added
----------------------------------------------------------------------------
Status|RESOLVED |REOPENED
Resolution|FIXED |---
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2013-11-21 9:21 UTC | newest]
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2011-05-17 14:28 [Bug libfortran/49024] New: REAL*16 ERFC_SCALED inaccuracy thenlich at users dot sourceforge.net
2011-05-23 11:01 ` [Bug libfortran/49024] " fxcoudert at gcc dot gnu.org
2011-05-23 20:54 ` fxcoudert at gcc dot gnu.org
2011-05-23 21:45 ` burnus at gcc dot gnu.org
2011-05-23 22:12 ` fxcoudert at gcc dot gnu.org
2013-11-20 22:19 ` fxcoudert at gcc dot gnu.org
2013-11-21 8:46 ` fxcoudert at gcc dot gnu.org
2013-11-21 8:46 ` fxcoudert at gcc dot gnu.org
2013-11-21 9:21 ` schwab@linux-m68k.org
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