> 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 ?
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.
Cheers,
Florent
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