On Tue, Mar 11, 2014 at 5:29 PM, Robert Bradshaw <rober...@gmail.com> wrote: > First off, to start with a funny anecdote, I remember working with > some of the early Sage devs way back in the day optimizing matrix > multiplication and we were baffled by the fact that numpy somehow > managed to have O(n^2) behavior into the thousand by thousand matrix > range :).
I remember precisely that happening to me. I was extremely impressed.... for a few minutes. > More serious responses below. > >> Sure, fair enough. If you're lucky enough to be dealing only with pure >> mathematical matrices, then the problem this PEP is addressing doesn't >> arise. Practical number crunching OTOH isn't so pretty, but it is >> useful :-). > > There are certainly times when one wants to work with arrays like this > in Sage, and it's perfectly fine to invoke numpy to do so. In general, > however, x*y (where x and y are of the same type, or coercible to the > same type) denotes multiplication as defined in the parent (Group, > Ring, Monoid, whatever) of x and y. This isn't special to matrices: it > applies to rationals, algebraic numbers, polynomials, permutations, > etc. The * operator is also used to denote an action, e.g. on scalar > multiplication of a matrix, a matrix acting on a vector, or the > integer ring on a abelian group like an elliptic curve. Pretty much > whatever would be represented on the blackboard by a \cdot or simply > placing symbols adjacent to each other. Relevant link is [1]. > > IMHO it seems odd to try to define a new infix operator that > specifically has "matrix multiplication" semantics. That seems out of > the domain of the Python language. If it were to be accepted, there's > no way Sage would start using * to do element-wise multiplication of > matrices. As founder of the project, I second Robert's assertion that no matter what, "there's no way Sage would start using * to do element-wise multiplication of matrices." [1] http://www.sagemath.org/doc/reference/coercion/ -- William Stein Professor of Mathematics University of Washington http://wstein.org -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at http://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.
