Maxima Function
kdelta (L1, L2)
is the generalized Kronecker delta function defined in
the itensor
package with L1 the list of covariant indices and L2
the list of contravariant indices. kdelta([i],[j])
returns the ordinary
Kronecker delta. The command ev(expr,kdelta)
causes the evaluation of
an expression containing kdelta([],[])
to the dimension of the
manifold.
In what amounts to an abuse of this notation, itensor
also allows
kdelta
to have 2 covariant and no contravariant, or 2 contravariant
and no covariant indices, in effect providing a co(ntra)variant "unit matrix"
capability. This is strictly considered a programming aid and not meant to
imply that kdelta([i,j],[])
is a valid tensorial object.