[Cfp-interest] TS 18661-4/N1785 - Reduction functions, correct rounding

[Vincent Lefevre]

Hi,

* TS 18661-4/N1785 §8 (reduction functions) doesn't say anything about
the sign of 0, except for n = 0. It is ambiguous because one doesn't
know whether the sign follows the usual IEEE 754 rules (which make
sense even here, as the order of the operations doesn't matter) or it
is unspecified.

* For the sums of length n = 0, is the value +0 even in
roundTowardNegative?

* TS 18661-4 should reserve names for correctly rounded versions of
the reduction operations. Note that the current P1788 draft standard
for interval arithmetic requires correctly rounded reduction
operations sum, dot, sumSquare and sumAbs.

* TS 18661-4 should reserve names for correctly rounded versions of
all math functions, such as asinpi, even though IEEE 754-2008 doesn't
recommend all functions: future revisions may add them. See also §9.1
of IEEE 754-2008: the functions in §9.2 are recommended, but otherwise
this is not an exhaustive list of what a language can specify.

Regards,

-- 
Vincent Lefèvre <vincent at vinc17.net> - Web: <http://www.vinc17.net/>
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