On Sun, Apr 18, 2010 at 10:08:28AM +0930, ross kyprianou wrote:
> >> Any ideas of why _repr_ might not be working inside the class?
> > Was this class that of the category or the parent?
>
> I made a copy of AlgebrasWithBasis.py (so that's the category isnt it?)
> and placed my version of _repr_ is various places within that code but
> it didnt override the default _repr_
>
> > If you do (with x some of your elements):
> > sage: x.__class__.mro()
> > you will see that the category classes appear quite late there, and in
> > particular after Parent. Hence, it is (currently) not possible to
> > override _repr_, or anything else implemented in Parent, by code in
> > categories.
>
> I called mro on an element P, as suggested...
>
> (P,Q,R)= MtxAlgebrasWithBasis(QQ).example(('P','Q','R')).algebra_generators()
> P.__class__.mro()
>
> Does the output (at the end of this reply) mean: _repr_ cant be
> overridden somehere as you stated above?
You currently have to implement _repr_term / _repr_ in the class for
the parent (resp. for the elements). You can't do this in the
categories. That sure is a misfeature, which we will fix soon. It just
turns out that in the use cases we got so far it was sufficient to
implement this at the level of parent/elements, not categories.
> (It would be a huge shame. I checked with support from both commercial
> players (Mma & Mple) and both said
> they dont support this but have been asked for it multiple times. I
> understand its been asked by our users also.
> And now that I need it, Im highly motivated to implement it :-)
> As a last resort - just to get some of my work progressing for now -
> Im happy to copy and customize enough
> existing categories code to make matrices work it but if I can do this
> properly it could end up in the sage code base for others to use.
> Question is is: it possible to implement this "properly"?
With enough stamina, everything is possible with Sage :-)
Kidding aside, yes, it sure is possible. Send me your code, and I
refactor it to its simplest form, as a basis for further work.
The most efficient would be to upload it on the Sage-Combinat queue,
but that will take some learning the tool:
http://wiki.sagemath.org/combinat/MercurialStepByStep; otherwise
e-mail is fine.
> All that is needed, to make a basic prototype matrix algebra, is
>
> Distributivity == P(Q+R) => PQ + QR (already working thanks to
> existing categories code)
> Non-commutivity PQ does not equal QR (also is working)
> Printing i.e. show "P Q + Q R" rather than "B[word: PQ] + B[word: PR]"
> (by overloading _repr_ or by some other means?)
> Substitution i.e. P^-1 * P results in identity - And - (P *
> Q).Transpose() results in Q.Transpose() + P.Transpose()
>
> So two tasks done - two to go if possible!
Keep up the good work!
Cheers,
Nicolas
--
Nicolas M. Thiéry "Isil" <nthi...@users.sf.net>
http://Nicolas.Thiery.name/
--
To post to this group, send an email to sage-devel@googlegroups.com
To unsubscribe from this group, send an email to
sage-devel+unsubscr...@googlegroups.com
For more options, visit this group at http://groups.google.com/group/sage-devel
URL: http://www.sagemath.org
