Wolfgang Zocher:
> Hello all,
>
> while trying to repair the broken components function in the itensor package I
> struggle with the concept of "indexed objects". The manual (MIT/LCS/TM-167)
> pg.13 says:
>
> ,,In ITENSR a tensor is represented as an "indexed object" . This is a
> function of 3 groups of indices which represent the covariant,
> contravariant and derivative indices." and ,,...the symbolic function
> representing the tensor".
>
> I can't realize the existence of such function wrt to itensor.lisp. It seems,
> that the currently not working function components() contains some leavings of
> an old implementation of indexed objects (i.e.the properties _TEXPRS_ and
> _TSUBR_ ). These properties only appear in components and they are pretty
> unused... (as far as I can see)
>
As far as I understand there is no any internal special function for
representing indexed tensor objects. They just mean that for example
for itensor
ZZ([A,B],[X,Y,Z])
is a tensor with two covariant and three contravariant indices.
But for Maxima in general this is nothing but function ZZ with
two arguments.
> Is there anybody out there who could give me a hint where to find informations
> about the implementation of _indexed objects_ in Macsyma?
>
I doubt that such information is available.
> Thanks,
> Wolfgang Zocher
>
--
Vadim V. Zhytnikov
<vvzhy@mail.ru>
<vvzhy@netorn.ru>