[GiNaC-devel] Another bug in clifford.cpp

[Chris Dams]

Dear all,

I found out that canonicalizing clifford objects was not functioning
properly. This was because a dirac_slash was automatically getting zero
as its metric. When canonicalizing clifford objects the anti-commutator
of two objects that were ordered in the wrong way is necesary. However,
if the metric is automatically set to zero, this anti-commutator is zero
too. I fixed this in CVS.

I do have two questions about the implementation
(1) Why are the indices in dirac_gamma (and with my patch in
dirac_slash) static? Does the dimension of them not matter? It now seems
that the dimension as used in the metric is always equal to the
dimension of the very first dirac_gamma/dirac_slash that is constructed.
(2) Why does the metric have indices? In view of the implementation of
get_metric the primary purpose of these indices seems to be to be
replaced by other indices. If that is the case why are they present in
the first place?

Best,
Chris