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P1788
I think the voting period on motion 10 is nearly on us. Discussion on
it seems to have been nonexistent since 10th Nov, or have I missed
something?
On the required functions, I like everything except
- compound. Only "recommended" in 754, and it seems not to give
much numerical benefit. It loses a lot of information in x
when x (and n) are small. If it were defined as (1+x)^n - 1,
I see the point.
As it's in 754, I suppose we can't change it, so I support
moving it to "recommended".
- rSqrt. Maybe I just don't know what application crucially
requires the extra ulp of accuracy this may give compared
with doing 1/sqrt(xx). At present I support moving it to
"recommended", but am persuadable.
In the "recommended" list
- I applaud the inclusion of sinPi and its kin, despite Dan Zuras's
disapproval.
- I think exp1 should be (e^x-1)/x, not (e^x-1-x)/x.
And atanPi is defined as \atan(x)/\pi, not \atan(x)\pi.
And atan2Pi needs a definition entry.
- It might be good if the authors make the "range" column of Table 2
consistent ("sign" has range as interval function, the others as
point functions). And make Tables 1 & 2 consistent with each other.
Personally I find the Table 1 "interval function" column not very
helpful and actually wrong in some ways. E.g. asin is defined on
_any_ interval according to the definition of interval extension
in section 1.1 -- not just on members of I[-1,1].
So maybe Table 1 should revert to just a "range" column?
- Nate Hayes makes a good point arguing for "nint" and "trunc" in
addition to "ceil" and "floor", so that all four rounding modes are
catered for.
As for Dan's general power, I don't like it. As an interval function
it seems "neither fish, flesh nor fowl, nor good red herring".
At present I expect to vote
M0010.10 List of required functions NO for reasons above.
M0010.20 Postpone details YES
M0010.30 General power NO for reason above.
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