std::numeric_limits::is_iec559

[Gabriel Dos Reis]

Geoffrey Keating <geoffk@geoffk.org> writes:

| Gabriel Dos Reis <gdr@integrable-solutions.net> writes:
| 
| > Roberto Bagnara <bagnara@cs.unipr.it> writes:
| > 
| > | I have always used std::numeric_limits::is_iec559 thinking that,
| > | as per the C++ standard, it yielded "[t]rue if and only if the type
| > | adheres to IEC 559 standard."
| > | 
| > | On a Mac OS X 10.4 machine with GCC 4.0.1, however, I get the value
| > | true for long doubles but, as far as I can tell, the layout of
| > | long doubles there does not conform to the 128-bit format specified
| > | by IEC 559.
| > 
| > I don't follow.  Exactly in what aspect do you believe the Mac OS X
| > 10.4 representation is not conformant to IEC 559?
| 
| It isn't conformant because the basic arithmetic is different. 

I'm intending to look further into this non-conformance issue.  I
would appreciate if you could point me to its spec.

-- Gaby