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