Re: differences of gfortran on amd64 and i386

[Girish Kulkarni <girish@athene.org.in>]

On Sun, 14 Jun 2009, Kamaraju S Kusumanchi wrote:
> Johannes Wiedersich wrote:
>
> > I have a rather funny and annoying problem with a third-party
> > fortran program. It is a non-free scientific program for some
> > physical calculations. I get different output values, if I compile
> > and run the same fortran code on amd64 or i386.

While this does mean that the Fortran program is not written
sufficiently carefully, the difference between i386 and amd64 could be
due to x87 and SSE floating-point units.  See David Monniaux's
interesting article:  http://arxiv.org/abs/cs/0701192.

> also try disabling the optimizations, compile with -Wall,
> -fbounds-check options and see if there is any change in the final
> results.

Also try -float-store.

--
Girish Kulkarni - Allahabad, India - athene.org.in/girish