maybe inf
xxx
that is, subscripted.
Independent of this notion, which is not in Mathematica 6.0, as far as I can
tell,
Mathematica has an infinity "function" DirectedInfinity.
in fact, Infinity is really a shorthand for DirectedInfinity[1].
The same indexing makes sense for intervals, e.g. x-x where x is an
interval
could be 0, too.
> -----Original Message-----
> From: maxima-bounces at math.utexas.edu
> [mailto:maxima-bounces at math.utexas.edu] On Behalf Of Raymond Toy
> Sent: Thursday, August 28, 2008 11:01 AM
> To: Barton Willis
> Cc: fateman at EECS.Berkeley.EDU; maxima at math.utexas.edu;
> maxima-bounces at math.utexas.edu
> Subject: Re: [Maxima] infinity correct maxima
>
> Barton Willis wrote:
> > maxima-bounces at math.utexas.edu wrote on 08/28/2008 09:01:21 AM:
> >
> >
> >> I'm not sure what is implemented, but the following sequence:
> >>
> >> x: inf;
> >> x-x;
> >> could result in zero, because it is the same infinity.
> >> so should (x^2-1)-(x+1)*(x-1).
> >>
> >> However,
> >> y:inf;
> >> x-y should result in undefined.
> >> Getting undefined arithmetic right would be just as important.
> >>
> >> Labeling each unique inf with an identifier is a way to do this.
> >
> > No, my code doesn't tag infinities this way. If we simply tagged
> > each infinity with a gensym identifier, it wouldn't be all that
> > hard to do, but getting through the test suite might be a chore.
>
> How would such a tagged inf be printed? Will it be printed
> inf<junk>?
> Or just inf?
>
> With or without tagging, I'm not sure I like the example of x-x
> returning 0, but inf-inf being undefined. I find that rather
> confusing.
>
> Ray
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