Re: floats and intervals, constants, 0.1, 1e400 and Inf
Arnold et al,
Arnold Neumaier wrote:
Michel Hack schrieb:
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> Indeed, a general rule for constant->interval conversion should be
> round-down for lower bound, round-up for upper bound (assuming the
> implementation is indeed in terms of bounds). The fact that same-type
> floats will be converted exactly is then simply a consequence of the
> fact that both "conversions" (being no-ops) yield the same result.
Yes.
By "constant" do you mean a 754 floating point number or an external
character representation?
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Though briefly discussed, I think nobody has shown strong emotions for
satandardizing mdpoint-radius interval representations.
I advocate against it.
Standardizing midpoint-radius arithmetic would complicate 1788's task
significantly. However, when we have our formal procedures in place,
someone can propose it and we can vote on whether we want to do it.
> Now, one concept that has not been discussed so far is whether there
> can be several interval types, with different precisions. If so, there
> would have to be conversion functions between interval types as well.
This is another issue not considered in my proposal.
The correct conversion would be by outward rounding the bounds.
Again, in what context? Also, using other than 754 types would
complicate 1788's task. We should consider what it would gain us
if we did so.
Baker
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R. Baker Kearfott, rbk@xxxxxxxxxxxxx (337) 482-5346 (fax)
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Department of Mathematics, University of Louisiana at Lafayette
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