On 11/15/08, Viktor T. Toth <vttoth at vttoth.com> wrote:
> On the topic of multiplying vectors and matrices, I've been meaning to make
> a suggestion: I think it might be a good idea to modify the dot product
> (perhaps tied to a global variable <groan> that determines if this new
> behavior is to be used) to allow the ELEMENTS of the matrices or vectors
> involved to be noncommutative.
Good news! There is already such a global variable!
It is named matrix_element_mult.
Its value is the name of the operator which is invoked to
carry out element-by-element multiplication when lists and/or
matrices are multiplied.
Of course the right way to handle this is to declare that matrix
elements are elements of a group or whatever with a specified
operator ... Maybe we'll get there someday.
> At present, for instance, a lot of quantum physics problems cannot be
> tackled in the "natural way" in Maxima, because they involve matrices with
> nonscalar elements, yet Maxima insists on commutative multiplication.
I don't know much about that. Does matrix_element_mult help?
best
Robert Dodier