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Re: 1.7.8: Fortran I/O rounding inaccuracy

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
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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