Olivier Verdier-2 wrote: > > There are two solutions to the A*B*C problem that are not quite > comparable, > and are not mutually exclusive either. > 1) allow dot(A,B,C): this would be a great improvement over > dot(dot(A,B),C), > and it could virtually be done within a day. It is easy to implement, does > not require a new syntax, and does not break BC > > 2) another solution, not incompatible with the first one, is to introduce > a > new operator in the python language. In the case that it be accepted by > the > python community at large (which is very unlikely, IMHO), be prepared to a > very long time before it is actually implemented. We are talking about > several years. > > I think that solution 1) is much more realistic than 2) (and again, they > are > not mutually exclusive, so implementing 1) does not preclude for a future > implementation of 2)). > > Implementation of 1) would be quite nice when multiplication of several > matrices is concerned. >
I agree these are not mutually exclusive. In other words, they are separate issues. So sure while I would not be *as* happy with a multi-input dot as I would with a new operator that could overload dot, I don't mean to discourage the multi-input dot from being pursued. By all means, it seems like a worthwhile addition if done correctly. I just don't think it solves the problem, that being how do we improve the semantics of numpy to be more "matrix" based. It is a *requirement* that the package support * (or some binary infix operator) for matrix mutliplication. We do this with the matrix type. But, almost all experienced users drift away from matrix toward array as they find the matrix class too limiting or strange - it seems only applicable for new users and pedagogical purposes. My own experience is that having two ways to do things makes software confusing and overly complex. It would be preferable to have a single class that supports matrix multiplication syntax. If that takes a year or two until it "hits the street" as a numpy release, so be it... we've got time. I think your time estimate is correct, although the actual time to implement and test the new python syntax would probably be much shorter - it is not so much a technical issue as one of socialization. What do we want to do? How can we convince the larger python community that this is a good idea for them too? Cheers, Tom K. -- View this message in context: http://www.nabble.com/matrix-default-to-column-vector--tp23652920p23914277.html Sent from the Numpy-discussion mailing list archive at Nabble.com. _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
