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MathGroup Archive 2006

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

  • To: mathgroup at smc.vnet.net
  • Subject: [mg66629] Re: Interval[{a,b}]-Interval[{a,b}] = 0?
  • From: Johan Grönqvist <johan.gronqvist at gmail.com>
  • Date: Wed, 24 May 2006 04:10:16 -0400 (EDT)
  • Organization: Lund University, Sweden
  • References: <e510r2$8eg$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

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)
> 
> RJF
> 


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