* [Bug fortran/33469] Add one digit to the default formatted output
2007-09-18 9:46 [Bug fortran/33469] New: Add one digit to the default formatted output dominiq at lps dot ens dot fr
@ 2007-09-18 9:47 ` dominiq at lps dot ens dot fr
2007-09-18 17:57 ` burnus at gcc dot gnu dot org
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From: dominiq at lps dot ens dot fr @ 2007-09-18 9:47 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from dominiq at lps dot ens dot fr 2007-09-18 09:47 -------
Created an attachment (id=14219)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=14219&action=view)
test case
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33469
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2007-09-18 9:47 ` [Bug fortran/33469] " dominiq at lps dot ens dot fr
@ 2007-09-18 17:57 ` burnus at gcc dot gnu dot org
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From: burnus at gcc dot gnu dot org @ 2007-09-18 17:57 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from burnus at gcc dot gnu dot org 2007-09-18 17:56 -------
A compiler comparison:
real(4) gfortran g95 NAGf95 ifort sunf95 openf95
default 808 0 808 808 0 0
1PG20.6 1881 1881 1881 1881 1881 1881
1PG20.7 808 808 808 808 808 808
1PG20.8 0 0 0 0 0 0
real(8)
default 1778 0 0 1778 0 0
1PG30.14 1978 1978 1978 1978 1978 1978
1PG30.15 1778 1778 1778 1778 1778 1778
1PG30.16 0 0 0 0 890 0
^^^ ?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33469
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2007-09-18 9:47 ` [Bug fortran/33469] " dominiq at lps dot ens dot fr
2007-09-18 17:57 ` burnus at gcc dot gnu dot org
@ 2007-09-19 9:54 ` fxcoudert at gcc dot gnu dot org
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From: fxcoudert at gcc dot gnu dot org @ 2007-09-19 9:54 UTC (permalink / raw)
To: gcc-bugs
------- Comment #3 from fxcoudert at gcc dot gnu dot org 2007-09-19 09:54 -------
(In reply to comment #0)
> Following a discussion on IRC with FX Coudert, I think the number of digits
> printed by default in formatted output should be increased by one.
Dominique, what is the output of your test program on ppc-darwin?
I otherwise agree with you: until (or unless) we get more clever formatted I/O,
we should increase the default format. I'm waiting for the real(16) output and
will then submit a patch.
--
fxcoudert at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |fxcoudert at gcc dot gnu dot
| |org
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2007-09-19 09:54:42
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33469
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2007-09-19 9:56 ` [Bug libfortran/33469] Default formats for real input are not precise enough fxcoudert at gcc dot gnu dot org
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From: fxcoudert at gcc dot gnu dot org @ 2007-09-19 9:55 UTC (permalink / raw)
To: gcc-bugs
--
fxcoudert at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |fxcoudert at gcc dot gnu dot
|dot org |org
Status|NEW |ASSIGNED
Last reconfirmed|2007-09-19 09:54:42 |2007-09-19 09:55:15
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33469
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From: fxcoudert at gcc dot gnu dot org @ 2007-09-19 9:56 UTC (permalink / raw)
To: gcc-bugs
--
fxcoudert at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Severity|enhancement |normal
Component|fortran |libfortran
Keywords| |wrong-code
Summary|Add one digit to the default|Default formats for real
|formatted output |input are not precise enough
Target Milestone|--- |4.3.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33469
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2007-09-19 9:56 ` [Bug libfortran/33469] Default formats for real input are not precise enough fxcoudert at gcc dot gnu dot org
@ 2007-09-19 12:38 ` dominiq at lps dot ens dot fr
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From: dominiq at lps dot ens dot fr @ 2007-09-19 12:38 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from dominiq at lps dot ens dot fr 2007-09-19 12:38 -------
Subject: Re: Add one digit to the default formatted output
> Dominique, what is the output of your test program on ppc-darwin?
real(4)
default 808
1PG20.6 1881
1PG20.7 808
1PG20.8 0
real(8)
default 1778
1PG30.14 1978
1PG30.15 1778
1PG30.16 0
real(16)
default 1999
1PG60.32 1999
1PG60.33 1999
1PG60.34 1999
1PG60.35 1999
1PG60.40 1999
but I have no way to know if the problem comes from NEAREST()
or from the I/O.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33469
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From: fxcoudert at gcc dot gnu dot org @ 2007-10-01 23:28 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from fxcoudert at gcc dot gnu dot org 2007-10-01 23:28 -------
Hum, the real(16) case looks like loads of fun to come!
$ cat k.f90
integer, parameter :: k = 16
character(80) :: buf
real(k) :: xk, yk
xk = 1.0_k - epsilon(xk)
write (buf,'(1PG60.40)') xk
read (buf,*) yk
write (*,'(1PG60.40)') xk
write (*,'(1PG60.40)') yk
if (xk /= yk) print *, "Mismatch"
print *
xk = 1.0_k + epsilon(xk)
write (buf,'(1PG60.40)') xk
read (buf,*) yk
write (*,'(1PG60.40)') xk
write (*,'(1PG60.40)') yk
if (xk /= yk) print *, "Mismatch"
print *
end
$ gfortran k.f90 && ./a.out
1.9999999999999999999999999999999753481000
4.9303806576313237838233035330174139355000E-32
Mismatch
1.0000000000000000000000000000000246519000
1.0000000000000000000000000000000246519000
(Also, in the case of real(16), you need to add an E4 to the format anyway.)
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33469
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From: fxcoudert at gcc dot gnu dot org @ 2007-10-02 0:37 UTC (permalink / raw)
To: gcc-bugs
------- Comment #6 from fxcoudert at gcc dot gnu dot org 2007-10-02 00:37 -------
(In reply to comment #5)
> Hum, the real(16) case looks like loads of fun to come!
Part of it is simply a libc bug. There are numbers close to 1.0 and -1.0 that
the darwin libc can't output properly:
$ cat k2.c
#include <stdio.h>
int main (void)
{
long double x;
x = 0.99999999999999998L;
printf ("%Lg\n", x);
printf ("%.60Lg\n", x);
x = -0.999999999999999999999999999999975L;
printf ("%Lg\n", x);
printf ("%.60Lg\n", x);
}
$ gcc k2.c && ./a.out
2
1.99999999999999997999999999999999548766360788798414493987417
-2
-1.99999999999999999999999999999997534809671184338108088348233
I've reported this to Apple (it is now bug #5516762). Otherwise, as far as I
can tell, the default format width seems wide enough for real(kind=16).
--
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From: dominiq at lps dot ens dot fr @ 2007-10-02 8:29 UTC (permalink / raw)
To: gcc-bugs
------- Comment #7 from dominiq at lps dot ens dot fr 2007-10-02 08:29 -------
Subject: Re: Default formats for real input are not
precise enough
> Part of it is simply a libc bug. There are numbers close to 1.0 and -1.0 that
> the darwin libc can't output properly:
Nice catch! The problem affects the vicinity of all the powers of 2, try
1.99999999999999998_16, 3.99999999999999998_16, ...
--
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From: fxcoudert at gcc dot gnu dot org @ 2007-10-02 23:28 UTC (permalink / raw)
To: gcc-bugs
------- Comment #8 from fxcoudert at gcc dot gnu dot org 2007-10-02 23:28 -------
Subject: Bug 33469
Author: fxcoudert
Date: Tue Oct 2 23:27:51 2007
New Revision: 128967
URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=128967
Log:
PR libfortran/33469
* io/write.c (write_real): Widen the default formats.
* gfortran.dg/default_format_1.f90: New test.
* gfortran.dg/default_format_2.f90: New test.
* gfortran.dg/namelist_print_1.f: Adjust expected output.
* gfortran.dg/real_const_3.f90: Adjust expected output.
Added:
trunk/gcc/testsuite/gfortran.dg/default_format_1.f90
trunk/gcc/testsuite/gfortran.dg/default_format_2.f90
Modified:
trunk/gcc/testsuite/ChangeLog
trunk/gcc/testsuite/gfortran.dg/namelist_print_1.f
trunk/gcc/testsuite/gfortran.dg/real_const_3.f90
trunk/libgfortran/ChangeLog
trunk/libgfortran/io/write.c
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33469
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2007-09-18 9:46 [Bug fortran/33469] New: Add one digit to the default formatted output dominiq at lps dot ens dot fr
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2007-10-03 19:30 ` dominiq at lps dot ens dot fr
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From: fxcoudert at gcc dot gnu dot org @ 2007-10-02 23:31 UTC (permalink / raw)
To: gcc-bugs
------- Comment #9 from fxcoudert at gcc dot gnu dot org 2007-10-02 23:30 -------
As I said, the default format is wide enough for powerpc-darwin. It's widely
possible that the new testcase gfortran.dg/default_format_2.f90 fails there,
though, due to the Apple printf() bug. Dominique, if you confirm that the new
testcase fails, I'll XFAIL it. Thanks!
--
fxcoudert at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution| |FIXED
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33469
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2007-09-18 9:46 [Bug fortran/33469] New: Add one digit to the default formatted output dominiq at lps dot ens dot fr
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From: dominiq at lps dot ens dot fr @ 2007-10-03 19:30 UTC (permalink / raw)
To: gcc-bugs
------- Comment #10 from dominiq at lps dot ens dot fr 2007-10-03 19:30 -------
gcc/testsuite/gfortran.dg/default_format_1.f90 passes the test if I replace
if (y /= x) res = res + 1
by
z=0.0_k
if (abs(x-y)>nearest(z,1.0_k)) res = res + 1
in the two places of test_r8, i.e. the tests fail for TINY() because the result
differs from the original value by ~+/-5.0E-324: the smallest denormalized
number. I have noticed that this happens for an odd number of iterations of
NEAREST(), but I did not figure out if the culprit was the WRITE() or the
READ(). I have also seen the same problem with xlf and g95.
I suggest that the test includes this change and does not xfail on Darwin.
--
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From: dominiq at lps dot ens dot fr @ 2007-10-03 19:34 UTC (permalink / raw)
To: gcc-bugs
------- Comment #11 from dominiq at lps dot ens dot fr 2007-10-03 19:34 -------
BTW I have forgotten to explain why I have to use an auxiliary variable 'z': if
I usenearest(0.0_8,1.0_8); I get
default_format_1_db.f90:70.29:
if (abs(x-y)>nearest(0.0_8,1.0_8)) print *, x, y, x-y
1
Error: Result of NEAREST underflows its kind at (1)
default_format_1_db.f90:84.29:
if (abs(x-y)>nearest(0.0_8,1.0_8)) print *, x, y, x-y
1
Error: Result of NEAREST underflows its kind at (1)
default_format_1_db.f90:93.25:
use test_default_format
1
Fatal Error: Can't open module file 'test_default_format.mod' for reading at
(1): No such file or directory
Producing a hard error for an underflow is indeed an incredibely clever idea!-(
Reminds me of a compiler which crunched NaNs and Infs with delight, but aborted
on underflow, very handy for waves simulations!
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33469
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