Dear All, I am going to fix problems pointed out by Chris in clifford.cpp. However I looking for developer's advises before that.
"CD" == Chris Dams <Chris.Dams@mi.infn.it> writes: CD> Anyone who writes code like
CD> indexed(squared_metric, alpha, alpha) CD> where alpha is a varidx should realize that he is in a state of CD> sin and really doing something that might break anytime. Please give me a hint why this is wrong. CD> By the way. Wouldn't it be a good idea to remove the restriction CD> that indices of clifford objects should be varidxes? I am going to remove this if nobody objects. CD> varidxes. Doesn't an up-index mean exactly the same as a down CD> one in that case? In the recent paper (p. 4) http://euklid.bauing.uni-weimar.de/templates/papers/f34.pdf the following defining identities of a Clifford algebra in a space with a metric g.i.j are used: e.i e.j + e.j e.i = g.i.j e~i e~j + e~j e~i = g~i~j however e.i e~j + e~j e.i = delta.i~j Does any one object to implementation of the last identity in GiNaC? Or e.i e~j + e~j e.i = g.i~j should be used instead? CD> What I also would like to know, is what on earth it means that CD> "generators satisfying the identities e~i e~j + e~j e~i = M(i, CD> j) for some matrix (metric) M(i, j), which may be CD> non-symmetric". Where did you see this? My ginac.info tells that e~i e~j + e~j e~i = M(i, j) + M(j, i) which is meaningful for non-symmetric M. Best wishes, Vladimir -- Vladimir V. Kisil email: kisilv@maths.leeds.ac.uk -- www: http://maths.leeds.ac.uk/~kisilv/