Re: Motion 31 Suggestions
On 2011-12-29 18:07:59 -0500, Ian McIntosh wrote:
> 3.2.1 arithmetic operation:
> "Constants such as 3 and TT are regarded as arithmetic operations whose
> number of arguments is zero."
> I disagree with treating constants as arithmetic operations instead of as
> constant values (interval datums). It adds too many complications in too
> many places (5.4.1, 5.4.2, 5.4.3, ...).
> If we treat constants as arithmetic operations, shouldn't we treat
> variables as arithmetic operations too? And if constants are arithmetic
> operations defined in the implementation library, should all constants be
> included in either section 5.6 or 5.7? And maybe all variables? Of course
> then we'd have to decide which constants (and maybe which variables?) are
> required and which are recommended. 8<) It's better to treat
> constants as what they are - constants. That of course means rewriting
> section 5.4.4 Constants, keeping some of the wording relating to how the
> value of a constant is determined.
I think the idea was to specify an interval extension, and variables
are already taken into account as a special case. That said, I don't
have a clear idea on the subject.
> 5.4.4 Constants:
> "an interval extension of a real constant is any zero-argument interval
> function that returns an interval containing c."
> Should this return the hull, instead of any interval containing the
> constant?
I think it is correct: this is an interval extension, not the
natural interval extension. The natural interval extension is
given in the next sentence. Remember, this is Level 1.
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Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)