(j3.2006) exception message on termination

[Rafik Zurob]

Just to expand on what Daniel said, the reporting of fp exceptions on STOP 
and ERROR STOP is OFF by default in F77, F90, F95 modes.  It's ON by 
default in F2003 and F2008 modes.

We haven't received complaints from users about the output, but our test 
team complained about inexact, since almost everything turns it on.  I 
think underflow is important enough (for some situations as Robert 
mentioned) that we shouldn't delete it or make it optional (if set) in the 
output.  As for inexact, while I can't think of a useful practical case 
for it, it is something that the IEEE modules (and IEEE-compliant 
hardware) can trap on.  So excluding it from the STOP/ERROR STOP output 
will be a bit of a red herring.

Regards

Rafik

j3-bounces at mailman.j3-fortran.org wrote on 12/06/2013 10:30:42 AM:

> From: Daniel C Chen/Toronto/IBM at IBMCA
> To: robert.corbett at oracle.com, fortran standards email list for J3 
> <j3 at mailman.j3-fortran.org>, 
> Cc: j3-bounces at mailman.j3-fortran.org
> Date: 12/06/2013 10:32 AM
> Subject: Re: (j3.2006) exception message on termination
> Sent by: j3-bounces at mailman.j3-fortran.org
> 
> XLF compiler has an option to report fp exceptions including 
> underflow and inexact.  It is default OFF.
> 
> Daniel
> 
> XL Fortran Development - IBM Toronto Software Lab
> Phone: 905-413-3056 
> Tie: 969-3056 
> Email: cdchen at ca.ibm.com
> http://www.ibm.com/software/awdtools/fortran/xlfortran
> 
> [image removed] Robert Corbett ---06/12/2013 04:06:43---Thinking 
> back on it, most of the complaints we received were about underflow 
> also.  Underflow is us
> 
> From: Robert Corbett <robert.corbett at oracle.com>
> To: fortran standards email list for J3 <j3 at mailman.j3-fortran.org>, 
> Date: 06/12/2013 04:06
> Subject: Re: (j3.2006) exception message on termination
> Sent by: j3-bounces at mailman.j3-fortran.org
> 
> 
> 
> Thinking back on it, most of the complaints we received were about 
underflow 
> also.  Underflow is usually harmless in codes such as root finders and 
> quadrature routines.  On the under hand, underflow can cause silent 
> bad results 
> in some matrix computations.
> 
> Robert Corbett
> 
> 
> 
> On 06/12/13 00:38, Malcolm Cohen wrote:
> > The only complaint we got was for reporting underflow, so we added
> an option to
> > suppress that one.
> >
> > We never report inexact.  I agree it is completely pointless to 
> report inexact,
> > in my opinion it was an oversight not to make than an exception to
> the reporting
> > rule.
> >
> > Cheers,
> >
> > -----Original Message-----
> > From: Robert Corbett
> > Date: ?? 25?6?12? 12:59
> > To: j3
> > Subject: (j3.2006) exception message on termination
> >
> > Can we delete the second and third sentences of paragraph 2 in 
> Clause 8.4 in the
> > upcoming revision?  They state
> >
> >        If an exception (14) is signaling on that image,
> >        the processor shall issue a warning indicating
> >        which exceptions are signaling; this warning
> >        shall be on the unit identified by the named
> >        constant ERROR_UNIT (13.8.2.8).  It is recommended
> >        that the stop code is made available by formatted
> >        output to the same unit.
> >
> > Sun FORTRAN 77 produced such output.  It was a constant source of 
complaints
> > from users.  As bad as Sun FORTRAN 77 was in this regard, it did not 
report
> > inexact exceptions, as is required by the text of the standard.
> >
> > Robert Corbett
> > _______________________________________________
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> > J3 at mailman.j3-fortran.org
> > http://mailman.j3-fortran.org/mailman/listinfo/j3
> >
> > 
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