>> On Sun, Jun 7, 2009 at 04:44, Olivier Verdier <zelb...@gmail.com> wrote: >>> Yes, I found the thread you are referring >>> to: http://mail.python.org/pipermail/python-dev/2008-July/081554.html >>> However, since A*B*C exists for matrices and actually computes (A*B)*C, why >>> not do the same with dot? I.e. why not decide that dot(A,B,C) does what >>> would A*B*C do, i.e., dot(dot(A,B),C)? >>> The performance and precision problems are the responsability of the user, >>> just as with the formula A*B*C.
> Robert Kern wrote: >> I'm happy to make the user responsible for performance and precision >> problems if he has the tools to handle them. The operator gives the >> user the easy ability to decide the precedence with parentheses. The >> function does not. On 6/7/2009 7:44 PM Eric Firing apparently wrote: > The function could, with suitable parsing of the argument(s): > (A*B)*C => dot( ((A,B),C) ) or dot( (A,B), C ) > A*(B*C) => dot( (A, (B,C)) ) or dot( A, (B,C) ) > Effectively, the comma is becoming the operator. Horribly implicit and hard to read! If something needs to be done to make ``dot`` approach the convenience of ``*``, I think that adding ``dot`` as an array method looks attractive. (A*B)*C => A.dot(B).dot(C) A*(B*C) => A.dot( B.dot(C) ) But no matter how you slice it, the left hand expression is more compact and easier to read. fwiw, Alan Isaac _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
