Date: Wed, 3 Mar 1999 02:19:11 -0500 (EST) From: "Crist J. Clark" <cjc@cc942873-a.ewndsr1.nj.home.com> To: A_Johns@TurnAround.com.au (Andrew Johns) Cc: cjclark@home.com, gjb@comkey.com.au, freebsd-questions@FreeBSD.ORG Subject: Re: FP Math Message-ID: <199903030719.CAA04352@cc942873-a.ewndsr1.nj.home.com> In-Reply-To: <36DCD162.AC62A10E@TurnAround.com.au> from Andrew Johns at "Mar 3, 99 05:06:26 pm"
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Andrew Johns wrote,
> "Crist J. Clark" wrote:
>
> > For example, the above program returns,
> >
> > inf
> >
> > On my SGI.
> >
>
> inf = infinity??
Yes, that is what the output means.
> ie: overflow
Yep.
> ie: exception if overflow is not trapped
Nope, there is no floating point exception, no trapping.
> => SGI is merely trapping the oveflow.
Right, which I would like my FreeBSD to do. This goes back to my
original question, that was dropped in the first response, how can I
make sure I am using IEEE STANDARD 754 Floating-Point Arithmetic,
where ('man math'),
Exceptions:
IEEE 754 recognizes five kinds of float-
ing-point exceptions, listed below in
declining order of probable importance.
Exception Default Result
__________________________________________
Invalid Operation NaN, or FALSE
Overflow +-Infinity
Divide by Zero +-Infinity
Underflow Gradual Underflow
Inexact Rounded value
NOTE: An Exception is not an Error unless
handled badly. What makes a class of excep-
tions exceptional is that no single default
response can be satisfactory in every
instance. On the other hand, if a default
response will serve most instances satisfac-
torily, the unsatisfactory instances cannot
justify aborting computation every time the
exception occurs.
The program itself never receives a SIGFPE in my example. My example
is not an 'exceptional exception.'
--
Crist J. Clark cjclark@home.com
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