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On 4/24/2013 7:54 AM, Vincent Lefevre wrote:
I think the only interval endpoints that would signify open would be +-oo and -0. I agree that -0 introduces a non-uniformity, but it slightly simplifies the programming, at least if 1/(-oo) -> -0 automatically. The big advantage is that 1/(-0) comes out as -oo rather than oo. That is, I think, a selling point. Having open/closed endpoints atOn 2013-04-24 07:24:24 -0700, Richard Fateman wrote:I am hoping that to the largest extent the use of the IEEE-754 infinities will be transparent to this distinction. I am perhaps naively assuming this comes up only in circumstances in which one computes 1/oo or 1/(-oo) and gets not-quite zero. Allowing the use of -0 provides an opportunity to encode [-oo,0) as [-oo,-0].From what I've heard, this was done by some implementations and this was the reason why sqrt(-0) was chosen to return -0. However I wonder whether introducing some particular non-closed intervals would be useful. And it would make the standard more complex.
every real would be more complicated, yes.. I assume that the use of -0 has been discussed and rejected some time previously by 1788 committee.
Since there is no distinction between 0 and +0, there is no encoding for (0,oo]. As for whether endponts at +-oo are denoted with [] or (), --- I would be pleased if this turns out to be a matter of printing protocol, and nothing else.I agree.