Is pynac still being actively developed? From its web pages it seems
not; anyway I would have thought that most of its functionality would
have found a better and better-maintained home in Sage.
Anyway, I've just discovered that all of this can be done using
Maxima:
p=expand((1+x+1/y)^10)
maxima.nterms(p)
All somebody needs to do is to rewrite the lisp code for nterms into
python - and there you go!
cheers,
Aladair
On Mar 22, 5:32 am, Burcin Erocal <bur...@erocal.org> wrote:
> On Sat, 21 Mar 2009 03:02:57 -0700
>
>
>
> Robert Bradshaw <rober...@math.washington.edu> wrote:
>
> > On Mar 21, 2009, at 2:01 AM, Craig Citro wrote:
>
> > >> I think that better way is to use maxima commands op, args, length,
> > >> atomp
>
> > > I think that for objects which come from Maxima, this is the right
> > > thing to do. However, not all symbolic objects in Sage are wrappers
> > > for Maxima objects -- in the case of expressions using pynac, the
> > > code above actually moves them over to Maxima (via strings and
> > > pexpect) and then ask for their length there (which probably
> > > ultimately uses the commands you mention). This is less than
> > > desirable, hence my claim that it was a terrible way to calculate
> > > the length. :)
>
> > > I think a first step might be to introduce a __len__ method for
> > > symbolic objects, but then, I'm not always sure what it should
> > > return.
>
> > I would argue that this is a good reason not to implement it :).
> > Something like nops would be trivial to implement though, and
> > probably a good idea.
>
> It's in pynac already:
>
> sage: var('x,y',ns=1)
> (x, y)
> sage: f = expand((1+x+1/y)^10)
> sage: f.nargs()
> 66
>
> I could hook this up to __len__ as well, since __getitem__ lets you
> access parts of the expression. E.g.,
>
> sage: f[0]
> x^10
> sage: f[1]
> 10*x^9
>
> Cheers,
> Burcin
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