Re: 1.7.8: Fortran I/O rounding inaccuracy

[Tim Prince <n8tm at aol dot com>]

On 3/7/2011 4:17 AM, Thomas Henlich wrote:
> > I doubt our compiler is Fortran 2008 compliant, as at maximum it will
> > be Fortran 2003
>
> An identical phrase appears in Fortran 2003.
>
> > Have you tested gfortran 4.3 on other platform ?
>
> Due to unavailability, I was not able to test this particular version
> on other platforms.
>
> Tested ok:
>
> gfortran 4.4 on Debian
> gfortran snapshot 20101129 on mingw32
>
> Bug confirmed:
>
> gfortran snapshot 20100408 (unofficial Cygwin build)

You haven't shown how you tested rounding modes UP or DOWN, which may 
not be implemented in gfortran, as those (I believe) require the 
IEEE_arithmetic module, which is still under development.  Doesn't the 
wording you quote apply to the binary value resulting from READ conversion?
In the default (without IEEE_arithmetic settings), it's not clear to me 
that f2003 or 2008 standards impose requirements beyond those of 
IEEE754, which allow the decimal representation to truncate after 17 
correct digits.
As Corinna said, the place to ask about progress in this area of 
gfortran is fortran@gcc.org.
Corinna is more of an expert on newlib than are we; the differences you 
quote between linux implementation on glibc and cygwin which you quote 
appear to be within newlib.

--
Tim Prince

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