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RE: 20000301: ncdump on DEC Alpha running Linux

Russ,

Thanks very much.  You're email led us on the path for compiler directives.


We are running linux on an Alpha and using the GNU C compiler (gcc) to
compile our C code.  With the gnu C compiler, there is a flag, '-mieee',
which solved the problem.

As I mentioned, we were having the same problem with the NCAR CCM which is
written in Fortran.  Here, we are using the Compaq Linux Alpha fortran
compiler.  The flag that solved the problem with the fortran compiler was
'-fpe3'.

Thanks very much for your help.

Todd

> -----Original Message-----
> From: Russ Rew [mailto:address@hidden]
> Sent: Wednesday, March 01, 2000 1:20 PM
> To: Hutchinson, Todd A.
> Cc: address@hidden; Boucher, Robert J.;
> address@hidden
> Subject: Re: 20000301: ncdump on DEC Alpha running Linux 
> 
> 
> >cc: "Boucher, Robert J." <address@hidden>
> >From: "Hutchinson, Todd A." <address@hidden>
> >Subject: problem with ncdump on Alpha
> >Organization: TASC
> >Keywords: 200003011629.JAA19719 netCDF ncdump DEC Linux
> 
> Hi Todd,
> 
> > I have been having a problem using ncdump on a DEC Alpha 
> running linux.  I
> > have compiled netcdf on my own, and downloaded an rpm 
> (precompiled binaries)
> > format distribution from the rufus linux repository.  In 
> both cases, I see
> > the following problem:
> 
> > If there is an extremely small value in the netcdf file, 
> and I use ncdump to
> > examine the data, ncdump reports a "floating exception" and 
> core dumps.  The
> > debugger reports:
> > Program received signal SIGFPE, Arithmetic exception 
> > at either line 221 or 247 of vardata.c
> 
> > I have been working with some data of my own which causes 
> this problem,
> > however, I have found an example on the netcdf mailing list 
> (from 1994)
> > which describes the problem (included below).
> 
> > I've downloaded the file which was attached to the original 
> email message
> > and reproduced the problem (i.e., core dump) that was 
> originally reported.
> > Further, I've been able to successfully read the same file 
> on an intel linux
> > box.  I've attached the file that Jean-Francoise originally 
> attached to his
> > email message.
> 
> > While the problem occurs with ncdump, it also occurs with 
> the NCAR Community
> > Climate Model which calls many of the netcdf functions.  I 
> would ulitimately
> > like to solve this problem in the CCM.
> 
> > Do you have any suggestions which may solve this problem?
> 
> I can duplicate the problem on our Alpha running OSF1 V4.0, but we
> don't have access to an Alpha running Linux.  On the OSF1 Alpha, the
> solution is to use the compiler flag "-ieee_with_inexact", as
> described in this support reply to the original posting:
> 
>   http://www.unidata.ucar.edu/glimpse/netcdf/791
> 
> I don't know if there is such a flag with Linux compilers.  If you
> find out, can you let us know, and also tell us whether this solves
> the problem?  If so, we'll try to put the test in the configure script
> to deal with this.  Thanks.
> 
> --Russ
> 
> _____________________________________________________________________
> 
> Russ Rew                                         UCAR Unidata Program
> address@hidden                     http://www.unidata.ucar.edu
>