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From:	"Dave Korn" <dave DOT korn AT artimi DOT com>
To:	<cygwin AT cygwin DOT com>
Subject:	RE: f77 compiler
Date:	Fri, 7 Jan 2005 18:00:12 -0000
MIME-Version:	1.0
In-Reply-To:	<Pine.A41.4.58.0501071110140.68358@phyast.nhn.ou.edu>
Message-ID:	<NUTMEGk04dryJkM4al700000db1@NUTMEG.CAM.ARTIMI.COM>
X-OriginalArrivalTime:	07 Jan 2005 18:00:13.0687 (UTC) FILETIME=[BC94C870:01C4F4E2]

> -----Original Message-----
> From: cygwin-owner On Behalf Of Dick Henry
> Sent: 07 January 2005 17:16

> In short, a program that works fine on my workstation gives different
> output on my laptop using the f77 compiler from cygwin. 

> I have no idea what's going on. 

  Nor does anyone else.  "Gives different output" is an entirely inadequate
description of the problem.  Are you doing floating point maths on systems with
different accuracy in the underlying hardware?  Is your code invoking undefined
or unspecified behaviour that would differ from system to system?  Do you place
huge variables on the stack and are suffering from the two systems having
different default stack sizes?  There are a million possibilities why the same
code might produce different output when compiled and run on two different
machines, but most of them are down to buggy code rather than buggy compilers.

>From a compiling standpoint, are there
> other qualifiers that I should be using?

  You mean, is there some secret flag such as "-fwork-correctly", without which
the cygwin f77 is deliberately supposed to produce garbage output?  Heh, come
on, is that even likely?

  "f77 --help -v >file.txt 2>&1" will produce a long file listing every single
option the compiler (and the rest of the toolchain) knows; search it for
"Options for Fortran" to find the fortran specific ones.  But the problem is
more likely in your code.

    cheers, 
      DaveK
-- 
Can't think of a witty .sigline today....


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