Am Donnerstag, den 15.09.2011, 15:22 -0700 schrieb Richard Fateman:
>
> (originally only responded to kcrisman...)
> -------- Original Message --------
> Subject:
> Re: [Maxima] inf and minf
> Date:
> Thu, 15 Sep 2011 12:56:20 -0700
> From:
> Richard Fateman
> <fateman at eecs.berkeley.edu>
> To:
> Karl-Dieter Crisman
> <kcrisman at gmail.com>,
> fateman at cs.berkeley.edu
>
>
> On 9/15/2011 12:44 PM, Karl-Dieter Crisman wrote:
> >> Message: 5
> >> Date: Thu, 15 Sep 2011 11:57:01 -0700
> >> From: Richard Fateman<fateman at eecs.berkeley.edu>
> >> To: Maxima - list<Maxima at math.utexas.edu>
> >> Subject: inf and minf
> >> Message-ID:<4E724A7D.7080802 at eecs.berkeley.edu>
> >> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> >>
> >> Do we need minf? (negative real infinity)
> >>
> >> Note that - minf is currently not simplified to inf.
> >>
> >> RJF
> >
> > Is there a pressing need to remove this? It seems like it would break
> > a lot of existing code (or at least cause annoyance for anyone using
> > Maxima for improper integrals).
> It's generally a hassle if you have two internal representations of the
> same value, at least if they coexist in the same subsystem. (There are
> indeed different ways of representing things because there are taylor
> series, polynomials, poisson series ... that can be equivalent). But in
> the general representation in maxima, 1/x is x^(-1) internally, -x is
> (-1)*x etc.
>
> I am trying to write a paper in which I mention the notion of
> DirectedInfinity as in Mathematica.
> ComplexInfinity is DirectedInfinity[].
> real positive infinity is DirectedInfinity[1]
> negative is DirectedInfinity[-1]
> and any point on the unit circle can denote a particular direction as
> argument to DirectedInfinity.
> -DirectedInfinity[1] is simplified to DirectedInfinity[-1].
> The analogous simplification is not done in Maxima.
>
> That's probably a misfeature. I wonder if Maxima really needs minf.
> other than seeing - - oo in wxmaxima, I have no specific issue.
In the year 2009 I have done an attempt to implement the concept of a
directed infinitiy. This is the posting with some code and results:
http://www.math.utexas.edu/pipermail/maxima/2009/015780.html
Dieter Kaiser