Re: Edge case conversions, exceptions to IEEE FPA
On Tue, 2008-11-11 at 13:32 -0800, R. Baker Kearfott wrote:
> Van et al,
>
> What's sacred about 1ULP? Might the programmer know the accuracy, which
> isn't necessarily 1ULP? Such a case would be an argument in favor of
> perhaps supplying a conversion of two floats, one representing the
> midpoint, and the other representing the accuracy (in the form of
> a radius, say). Thus, we WOULD have two conversion routines, one
> for midpoint-radius, and one for lower bound and upper bound.
For an FP number not known to be exact, the closest to exact it can be
is 1/2 ulp each way.
> Connecting these conversions to programming languages is a separate
> issue. Do we want the two routines defined at the 1788 operation
> level, or at the programming language level?
I think conversions beyond what P754 specifies belong at the programming
language level.
The P1788 standard should say "An interval is represented by two
floating-point numbers; the first is the lower bound of the interval and
the second is the upper bound."
We've been whipping up a tempest in a teapot.
--
Van Snyder | What fraction of Americans believe
Van.Snyder@xxxxxxxxxxxx | Wrestling is real and NASA is fake?
Any alleged opinions are my own and have not been approved or
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