[GiNaC-devel] Improved dummy index renaming -> clifford exam fails

[Vladimir Kisil]

>>>>> "CD" == Chris Dams <Chris.Dams at mi.infn.it> writes:
    CD> Here one
    CD> clearly sees that neither contractiong g~mu~mu nor g.mu.mu makes
    CD> any sense. 

	The mentioned expression indexed(squared_metric, alpha, alpha) did
  not stand for a contractions, it was simply an abbreviation for
  pow(e.alpha,4)=pow(g.alpha.alpha,2). However I will rewrite clifford.cpp
  without this sort of "optimisation". 

    CD> This is why I was wondering in an
    CD> earlier email whether we should even allow matrices to carry
    CD> indices with a variance. If g is the metric tensor g with up
    CD> indices should be the inverse of g with down indices.
 
 Why not use the agreement from the second sentence to make sense for
  the first one?

    CD> If g is the metric tensor, it automatically obeys g.i~j =
    CD> delta.i~j.  Actually, this simplification is done automatically
    CD> in GiNaC. It is in the function ex
    CD> tensmetric::eval_indexed(const basic & i) const.

	So I only need take care on it if metric is given by a matrix?

	Best,
	Vladimir
-- 
Vladimir V. Kisil     email: kisilv at maths.leeds.ac.uk
--                      www: http://maths.leeds.ac.uk/~kisilv/