Strange, Gmail has cut my example. Here it is normally.
* [1 2]* *A = [3 4]* * [5 6]* *B = [7 8]* * [a d]* *C = [b c]* *(A*B)@C* *=* *[5 12] [a d]* *[21 32] @ [b c]* *=* *[5a+12b 5d+12c ]* *[21a+32b 21d+32c]* *A*(B@C)* *=* *[1 2] [5a+6b 5d+6c]* *[3 4] * [7a+8b 7d+8c]* *=* *[5a+6b 10d+12c]* *[21a+24b 28d+32c]* 2014-03-18 16:29 GMT+01:00 Robert Kern <robert.k...@gmail.com>: > On Tue, Mar 18, 2014 at 3:22 PM, Christophe Bal <projet...@gmail.com> > wrote: > > About weak-left. You need to define a priority of @ the matrix product > > regarding to * the elementwise product because (A*B)@C <> A*(B@C) : see > the > > example above. I say that also from a mathematical point of view. > > What example above? > > > Using mathematical like notations, Matrix1 * Matrix2 * 3 can be written > > because (Matrix1 * Matrix2) * 3 = Matrix1 * (Matrix2 * 3). > > This seems to argue against what you just said. > > > That's why I think that the weak-left is the better choice. > > But this is true as well: > > 3 * Matrix1 * Matrix2 = (3 * Matrix1) * Matrix2 = 3 * (Matrix1 * Matrix2) > > Does that expression argue for tight-left? > > -- > Robert Kern > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion >
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