Re: On writing negative zero - with or without sign



tholen@xxxxxxxxxxxx wrote:
James Giles writes:
....
Interval arithmetic carries *a* *lot* more information.

There's your "magic".

Yes, if you provide the I/O library with a new data type
(intervals) the I/O thenhas something else to work with.
It's not magic, it's well defined, hardnosed, pragmatic
I/O.

So, I answer your question about the magic by referring to something
you brought up, and now suddenly it's not magic anymore. Why am I
not surprised?

Your recommendations about how to supress (or not supress)
signs *never* mentioned any auxillary information being
provided to the I/O library. (Newsgroup archived, people
can check). Your suggestions really did require magic.

By the way, reporting error propagation analyses need no changes
to the IEEE nor to I/O. They're both admirably up to the task.


[...] I specified my concept
of an exact zero.

Yeah, the difference of two identically represented values
(with no qualifications about their origins). That's the
opposite of everyone else's definition of exact anything.
Isn't it revealing that a difference resulting in zero was the
only condition to raise the inexact conditon on some
hardware?

No one will buy a backward step as progress. Mysticism is a
dark age phenomenon.

Irrelevant, given that I haven't proposed any backward step.

In the opinion of one person.

I say it because there aren't more than two *IMPORTANT*
outcomes.

Just because a third one isn't important to you doesn't mean that it
can't be important to someone else.

And the existing mechanism requires *no* additional features
or changes in the rules of I/O for you to voluntarily keep track
of as many irrelevancies as you wish. I just don't want yet
another raft of features and options that I have to work hard
to turn off that provide no sensible value.

....

You *defined* exact zero as the difference
of two values with identical internal represenations.

But I used an example that was quite different from your
thermometer example.

You gave two numbers of unknown provenance. For all I know
you read them off a list of recorded temperatures. You gave
*no* qualifications regarding their provenance in your definiton
of "exact". You didn't even suggest that any such qualifications
were forthcoming or that any might be relevant. In fact, your
statement was quite devoid of any notion of exceptions to your
definition at all.


We haven't been talking about that. We've been talking about an
exact zero. I'll leave it to the standards committee members to
clarify the standard.

Good, then there's nothing to discuss at all. There aren't
exact zeros.

--
J. Giles

"I conclude that there are two ways of constructing a software
design: One way is to make it so simple that there are obviously
no deficiencies and the other way is to make it so complicated
that there are no obvious deficiencies." -- C. A. R. Hoare


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