Re: Alternative atan2 (was Motion 52: final ...)
On 2013-12-03 04:41:36 -0500, Michel Hack wrote:
> Right -- but atan2p must be exposed in the standard in order to
> define the interval function atan2_sharp piecemeal, based on interval
> extensions of point functions. I think we don't need atan2m, though
> the pair atan2, atan2m would be another possibility. The range of
> atan2_sharp would then be (-pi,+2pi). There is no point function
> with that range, which is why atan2_sharp cannot be the extension of
> a single point function.
What I mean is that IMHO, atan2p should be a helper function: it
is defined in the standard at Level 1, but it is not part of the
library. The implementation of atan2_sharp can use any internal
function (not visible by the user).
> If the asymmetry of a (-pi,+2pi) range bothers people, we might be
> able to define an atan2_sharp based on all three of atan2, atan2p and
> atan2m (and a range of (-2pi,+2pi), symmetrical), but the piecemeal
> definition would be more complicated.
We should think about it. One may want to have nice relations
between atan2_sharp(Y,X), atan2_sharp(Y,-X), atan2_sharp(-Y,X)
and atan2_sharp(-Y,-X).
--
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
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