[GiNaC-devel] Proposal: matrices may no longer be given varidxes.

Dear all, As discussed recently on this list, if we have a matrix M, both M~0~0 and M.0.0 evaluate to the same matrix element. This idicates that the variance of a varidx given to a matrix really doesn't mean anything. Therefore I propose to add code to the method matrix::eval_indexed that checks whether the indices are idxes (in the sense of is_exactly_a<idx>) and to throw an exception if they are not. What do other developers think? Obviously this could break some code out there. Best wishes, Chris