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Offline harold

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Interval arithmetic questions
« on: August 07, 2011, 12:07:34 pm »
I'm doing some interval arithmetic, and I can't seem to find the answer to this:

When adding two intervals where one of them is empty, what is the result?
For example, [a, b] + {} =
  • empty
  • [a, b]
  • undefined
  • ????
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Offline ben_g

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Re: Interval arithmetic questions
« Reply #1 on: August 07, 2011, 02:23:08 pm »
I think the result would be ERR:DIM MISMATCH, so it's undefined.
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Offline fb39ca4

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Re: Interval arithmetic questions
« Reply #2 on: August 07, 2011, 02:26:16 pm »
These aren't matrices, but I also think it is undefined.
Interval addition is defined as [a,b]+[c,d]=[a+b,c+d], and since c and d are undefined, [a+undefined,b+undefined], would be [undefined, undefined] or just undefined.
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Offline Horrowind

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Re: Interval arithmetic questions
« Reply #3 on: August 07, 2011, 02:56:31 pm »
to rephrase the t0xic_kitt3ns statement: there is no empty intervall, {} is the empty set, and therefore can not be added to an intervall.
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Offline AngelFish

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Re: Interval arithmetic questions
« Reply #4 on: August 07, 2011, 03:40:12 pm »
It depends on what you're asking. If you're asking how to add the null set to an interval, it's undefined. If you're asking how to add an interval equivalent to ]a,a[, then the answer is that the interval remains unchanged.
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Offline harold

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Re: Interval arithmetic questions
« Reply #5 on: August 07, 2011, 03:53:40 pm »
ok thanks, it looks like it's undefined
shortly after making the first post I changed the algorithm somewhat so that it will never have to attempt interval addition where one is the empty interval, so I don't really need this anymore, but thanks anyway
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