Strange Bug(?)



There is a discussion of inf-inf  and (in some sense) similar problems
related to intervals in
http://www.cs.berkeley.edu/~fateman/papers/interval.pdf

why similar?

intervals x-x  also don't simplify to zero  e.g.  [-1,1] - [-1,1]   is
[-2,2] not 0.

RJF
 

> -----Original Message-----
> From: maxima-bounces at math.utexas.edu 
> [mailto:maxima-bounces at math.utexas.edu] On Behalf Of Raymond 
> Toy (RT/EUS)
> Sent: Friday, April 18, 2008 9:21 AM
> To: Stavros Macrakis
> Cc: ronis at ronispc.chem.mcgill.ca; maxima at math.utexas.edu
> Subject: Re: [Maxima] Strange Bug(?)
> 
> Stavros Macrakis wrote:
> > PS I think there's a good argument to be made for having Maxima do
> > something similar with inf/minf it generates, making each one
> > distinct.  I know that someone (Raymond?) is also working on having
> > the simplifier not do inf-inf=>0, but there are lots of places other
> > than the general simplifier which need to be changed (rat
> > representation, compare, etc.).
> 
> I've kind of stopped working on it.  It seems to be working, 
> but there 
> are several places in the code where inf-inf is generated and 
> returning 
> 0 works but returning inf causes problems.
> 
> I believe Barton has a simplus simplifier and he's run into 
> similar issues.
> 
> Ray
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