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From: "kargl at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/35036] illegal E format descriptor produces wrong output
Date: Thu, 31 Jan 2008 04:10:00 -0000 [thread overview]
Message-ID: <20080131022457.25988.qmail@sourceware.org> (raw)
In-Reply-To: <bug-35036-15709@http.gcc.gnu.org/bugzilla/>
------- Comment #4 from kargl at gcc dot gnu dot org 2008-01-31 02:24 -------
(In reply to comment #3)
> Subject: Re: illegal E format descriptor produces wrong
> output
>
> Hi,
>
> | ------- Comment #2 from kargl at gcc dot gnu dot org 2008-01-31 01:46
> -------
> | (In reply to comment #0)
> | > "E8.0" is an illegal format descriptor,
> |
> | Can you cite from the Fortran 95 standard why this is illegal?
>
> Good question :-) Unfortunately, I don't have a Fortran 95 reference
> at hand, and so let me refer to the F77 standard:
>
> http://www.fortran.com/fortran/F77_std/rjcnf.html
>
>
> <QUOTE>
> 13.5.9.2.2 E and D Editing.
> The Ew.d, Dw.d, and Ew.dEe edit descriptors indicate that the external
> field occupies w positions, the fractional part of which consists of d
> digits, unless a scale factor greater than one is in effect, and the
> exponent part consists of e digits. The e has no effect on input.
>
> [. . .]
>
> The scale factor k controls the decimal normalization (13.5.7). If -d
> < k <= 0, the output field contains exactly |k| leading zeros and d -
> |k| significant digits after the decimal point. If 0 < k < d + 2, the
> output field contains exactly k significant digits to the left of the
> decimal point and d - k + 1 significant digits to the right of the
> decimal point. Other values of k are not permitted.
> </QUOTE>
>
> When d = 0, the only possible value for the scaling factor k is 1.
> Since "Other values of k are not permitted", you *must* use "1P"
> with d = 0, as "1PE8.0". Q.E.D.
>
> . . . I know this is a rather roundabout logic, and I'm not 100% sure,
> actually. I'm curious.
>
> Now, *if* "E8.0" is legal, what output should be generated for a value
> of 1e5 ? "0.E5" ?
Actually, I think the 'correct' output might be 0.E6.
There is no restriction in F95 that d must be positive in Ew.d.
In 10.6.5.1, it clearly states that k = 0 at the beginning of
execution of an input/output statement. The wording you quote
above is (almost) identical to F95 language, so one could argue
that the -d < k <= 0 is true when d = 0 and k = 0. Yes, it might
be a stupid interpretation, but then again the standard sometime
defies logic.
In any event, gfortran is definitely giving a bogus answer
of 0E+1, and your desired output of ******* is probably the
right thing to do.
jerry, any comments?
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35036
next prev parent reply other threads:[~2008-01-31 2:25 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-31 2:01 [Bug fortran/35036] New: " furue at hawaii dot edu
2008-01-31 2:25 ` [Bug fortran/35036] " pinskia at gcc dot gnu dot org
2008-01-31 3:06 ` kargl at gcc dot gnu dot org
2008-01-31 3:10 ` furue at hawaii dot edu
2008-01-31 4:10 ` kargl at gcc dot gnu dot org [this message]
2008-01-31 4:44 ` furue at hawaii dot edu
2008-01-31 5:46 ` kargl at gcc dot gnu dot org
2008-01-31 6:55 ` jvdelisle at gcc dot gnu dot org
2008-01-31 6:56 ` furue at hawaii dot edu
2008-01-31 8:17 ` jvdelisle at gcc dot gnu dot org
2008-01-31 14:10 ` burnus at gcc dot gnu dot org
2008-02-02 8:28 ` jvdelisle at gcc dot gnu dot org
2008-02-02 11:14 ` dominiq at lps dot ens dot fr
2008-02-02 19:37 ` jvdelisle at gcc dot gnu dot org
2008-02-03 0:07 ` jvdelisle at gcc dot gnu dot org
2008-02-21 2:21 ` jvdelisle at gcc dot gnu dot org
2008-02-21 2:24 ` jvdelisle at gcc dot gnu dot org
2008-02-21 2:24 ` jvdelisle at gcc dot gnu dot org
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