Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2006
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2006

[Date Index] [Thread Index] [Author Index]

Search the Archive

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


  • Prev by Date: Re: Interval[{a,b}]-Interval[{a,b}] = 0?
  • Next by Date: Re: Installation error
  • Previous by thread: Re: Interval[{a,b}]-Interval[{a,b}] = 0?
  • Next by thread: Re: Interval[{a,b}]-Interval[{a,b}] = 0?