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

*To*: mathgroup at smc.vnet.net*Subject*: [mg66639] Re: [mg66613] Interval[{a,b}]-Interval[{a,b}] = 0?*From*: Andrzej Kozlowski <akoz at mimuw.edu.pl>*Date*: Thu, 25 May 2006 02:58:09 -0400 (EDT)*References*: <200605240701.DAA08477@smc.vnet.net> <A22AA36D-C546-42C6-AC08-5C5D4F8C8662@mimuw.edu.pl>*Sender*: owner-wri-mathgroup at wolfram.com

On 24 May 2006, at 19:46, Andrzej Kozlowski wrote: > > On 24 May 2006, at 16:01, Richard Fateman wrote: > >> Is this a bug or a feature? >> Notice that Interval[{-1,1}]-Interval[{-1,1}] is Interval[{-2,2}]. >> >> (I'm using Mathematica 5.1) >> >> RJF >> > > I get > > Interval[{-1,1}]-Interval[{-1,1}] > > > Interval[{-2,2}] > > In[6]:= > $Version > > Out[6]= > 5.1 for Mac OS X (October 25, 2004) > > This is most certainly correct (as, I think, you point out in your > post). So whatever you have found, is neither a bug or a feature of > my copy of Mathematica 5.1. Hmm... perhaps they have some "cracked" > copies of Mathematica at Berkley? ;-) > > Andrzej Kozlowski > Tokyo, Japan It took me more than 12 hours to understand the point of RJF's post... I don't think putting the entire contents into the subject and then formulating the body so that it seems to be saying the opposite of what one wants to say, is a good policy (if one is really hoping for a response, of course. ) Yes, Mathematica does return In[8]:= Interval[{a,b}]-Interval[{a,b}] Out[8]= 0 Obviously that is because Mathematica does implement interval arithmetic with symbolic end points. If something is not implemented I don't think it makes sense to call it a bug or a feature. Andrzej Kozlowski

**References**:**Interval[{a,b}]-Interval[{a,b}] = 0?***From:*"Richard Fateman" <fateman@cs.berkeley.edu>