Bill Walster provided an interesting reference:
<http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&cad=rja&ved=0CGoQFjAJ&url=http%3A%2F%2Fwww.oracle.com%2Ftechnetwork%2Fsystems%2Finterval-angles-150228.pdf&ei=z6-TUt3cBMrloATN6oKQDw&usg=AFQjCNHDxLvcZD0XV94WnfOtX_Ktk0h6TQ&bvm=bv.57127890,d.cGU>
*MH "Interval Angles and the Fortran ATAN2 Intrinsic Function",
by Bill Walster
I just skimmed the article, and if I understand it correctly, the point
it makes is that, for intervals, the restriction of the atan2() range
to [-\pi, +\pi] would force some evaluations to return the essentially
useless [-\pi, +\pi] instead of a sharp enclosure that straddles \pi.
The same may apply to the other inverse-trig functions.
Is there something we can do about this?
Michel.
P.S. The article also implies that one can recover the turn count of
a rotation angle from a direction angle, but I need to read this
more carefully...
---Sent: 2013-11-25 20:48:31 UTC