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Re: Motion 52: final "Expressions" text for vote

On 11/25/13 6:06 PM, Vincent Lefevre wrote:

On 2013-11-25 15:35:13 -0500, Michel Hack wrote:

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.

I think that atan2 is a bit particular. Do you have an example
with a conventional inverse-trig function (asin, acos, atan)?

What about asin([1/2, 3/2]) and acos([1/2,3/2])?


You can have similar problems with box arithmetic on complex numbers,
like log(-1+[-eps,eps]*I), but here we have only real numbers.