------- Additional Comments From gdr at integrable-solutions dot net
2005-04-08 14:15 -------
Subject: Re: operator-(const T&, const complex<T>&) vs operator-(const
complex<T>&, const complex<T>&)
"kreckel at ginac dot de" <[EMAIL PROTECTED]> writes:
| (In reply to comment #11)
| > I think we need more careful analysis and tracking of both C99, C++ and
| > LIA-3.
|
| Apart from looking at standards, we could also try to use our brains, right?
It
| must be possible to answer the question whether the current behavior is right
or
| not by analogy with real numbers, ie. simply by looking at the imaginary part
alone.
|
| On systems without signed zero, there is no problem.
|
| On systems with -0.0, the code is trying to compute 0.0 - 0.0. Can that
| possibly be -0.0? If the answer is _no_, then this is a bug and it ought to
be
| fixed. Period. If the asnwer is _yes_, then, well, then I'm bemazed and
confused.
Thatis the mathematical question/answer. The real issue is this:
* in operator-(const T&, const complex<T>&), should the imaginary
part eve be touched?
there are vairous ansewrs. And, yes we've been using our brains.
|
| BTW: I've always tought that systems that distinguish between 0.0 and -0.0,
but
| not between 0.0 and +0.0 are slightly broken from a mathematical point of
view.
If you ask me, any system with signed zeros is broken, to start with.
-- Gaby
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20758
