On Wednesday, April 2, 2014 7:35:45 PM UTC+2, Matthew wrote: > > Yeah, Wild subclasses from Expr, alas. The logpy solution is to have a > dispatched isvar function. > > It seems to me that the all tensor indices are in some sense wild. > Shouldn't A[i, -i] unify to A[j, -j] ? >
Actually not, that was a particular case because A(i, -i) is A(j, -j), and this is also equivalent to a scalar (j and -j are summed over). A(i, j) instead is equivalent to a matrix. If A has associated components data, A(i, j).data is the N x N ndarray, and A(i, -i) is the trace. Consider A(i, -i, j) and A(j, -i, i), these are not equal and should not unify, not even if both i and j are wild. Of course a tensor constructor would raise an exception if an index is repeated more than twice. -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/d7b6882e-d224-48b9-8261-bd5ff81cb84c%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
