On Wed, 16 Nov 2011 15:10:54 +0100 Florent Hivert <florent.hiv...@lri.fr> wrote:
> > Pynac supports indexed expressions already. It just isn't wrapped in > > Sage yet. Again, there is an experimental patch available: > > > > http://sage.math.washington.edu/home/burcin/indexed_expression-20110727.patch > > > > Since you can wrap any hashable Python object in a symbolic > > expression with SR._force_pyobject(), this could replace your > > IndexedVarExpr class. > > > > I would appreciate any help with cleaning up these patches, adding > > doctests etc. so they can be merged. :) > > I'll try to cleanup this one, though I don't know anything about > Pynac's internal... Is there a lot more work to do than adding > doctests ? It should be only doctests, but you never know what comes up. :) I haven't looked at the patch in detail. I don't recall if any low level modification is needed. I'll be on IRC if you run into anything. Thanks a lot for looking into this. > By the way my buggy implementation revealed something that looks > strange to me: > > sage: Z = IndexedVar("Z") > sage: ex = (Z[1] + Z[2])/(Z[3] + Z[4]) > sage: ex > (Z[1] + Z[2])/(Z[3] + Z[4]) > sage: ex.numerator() > ERROR: An unexpected error occurred while tokenizing input > The following traceback may be corrupted or invalid > The error message is: ('EOF in multi-line statement', (647, 0)) > > --------------------------------------------------------------------------- > TypeError Traceback (most recent call > last) [...] > TypeError: unable to make sense of Maxima expression 'Z[2]+Z[1]' in > Sage > > Do we have to call Maxima to compute the numerator of a rational > fraction ? Is seems to me that Pynac/Ginac should be able to do it by > themselves. Unfortunately, we still call maxima for a lot of trivial operations. For example, pynac can easily handle the functions Expression.{coeff,poly}(). Feel free to open tickets for these issues. Cheers, Burcin -- 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
