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Subject: Re: [boost] boost interval arithmetic
From: Павел Кудан (coodan_at_[hidden])
Date: 2015-01-15 07:00:22

>There is no U decompositionin boost interval

As well a unite operation :) But the question is simpler - does statement  [-inf, inf] IS( [-inf, -1] U [1, inf])  have any sense from mathematical point of view.

And another simple question is can class which pretending on inclusion in C++ have bad behaviour and return corrupted results instead of correct?

>You can say
>OR( [-inf, -1], [1, inf] ) -> [-inf, inf]
>and also
> [-inf, inf] == OR( [-inf, -1], [1, inf] )
>but there is no operator that decomposes and interval into subintervals.
But mathematics, nevertheless, is not limited to someone's conceptions or misconceptions. It even not is limited by lacks of some operators in someone's classes.

Or we can state that 2 + 2 == [-inf, inf] and do no calculations :)
>You are using a multi-interval argument to evaluate a single-interval
>library. That's wrong. A multi interval is not the same as a single
>interval, but we all know that...
OK, you say it wrong. But why doing this is wrong for me, and right for boost interval class?

May be this class some kind of god - to make wrong things right?

'A multi interval is not the same as a single interval', as you just said.

OK, but that is enough to conclude that  [-inf, inf] IS( [-inf, -1] U [1, inf]) is not true and this operator returns not correct result, no matter is the way it corrupts own result documented or not.

And we all know that... having operator which silently returns not correct result leads to multiple other hardly located mistakes.

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