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Re: Interval[{a,b}]-Interval[{a,b}] = 0?

Richard Fateman wrote:
> Is this a bug or a feature?
> Notice that Interval[{-1,1}]-Interval[{-1,1}] is Interval[{-2,2}].

Interval arithmetic with a hopefully understandable notation:

You start with [-1,1] and subtract from that [-1,1]
This means:

Result = { x-y | x and y are in [-1,1] }

Then the Result will be A = [-2,2], and this is what you get.

Try also [-1,1] * [-1,1] to see that you get a result obtained in the
same way.

This is good for calculating with numbers having errors, among (probably)
other things.

say [x-error,x+error] - [y-error,y+error] and you get the result x-y
with the error in the form [x-y - 2error, x-y + 2error]

Good for handling experimental data.

/ johan

> (I'm using Mathematica 5.1)

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