Re: Radians Or Degrees?

On Fri, 15 Mar 2024 11:23:45 +0100
Terje Mathisen <terje.mathisen@tmsw.no> wrote:

Michael, I for the main part agree with you here, i.e. calculating
sin(x) with x larger than 2^53 or so, is almost certainly stupid.
 
Actually using and depending upon the result is more stupid.
 
OTOH, it is and have always been, a core principle of ieee754 that
basic operations (FADD/FSUB/FMUL/FDIV/FSQRT) shall assume that the
inputs are exact (no fractional ulp uncertainty), and that we from
that starting point must deliver a correctly rounded version of the
infinitely precise exact result of the operation.
 
Given the latter, it is in fact very tempting to see if that basic
result rule could be applied to more of the non-core operations, but
I cannot foresee any situation where I would use it myself: If I find
myself in a situation where the final fractional ulp is important,
then I would far rather switch to doing the operation in fp128.
 
Terje
>

To make it less tempting, you could try to push for inclusion of
rsqrt() into basic set. Long overdue, IMHO.

Right now, I can't think of any other transcendental that I really want
to elevate to higher status. It seems to me that elevation of log2(x)
and of 2**x will do no harm, but I am not sure about usefulness.