[Numpy-discussion] Preliminary thoughts on implementing __matmul__

Charles R Harris charlesr.harris at gmail.com
Wed Aug 6 19:24:59 EDT 2014

On Wed, Aug 6, 2014 at 4:57 PM, Nathaniel Smith <njs at pobox.com> wrote:

> On Wed, Aug 6, 2014 at 4:32 PM, Charles R Harris
> <charlesr.harris at gmail.com> wrote:
> > Should also mention that we don't have the ability to operate on stacked
> > vectors because they can't be identified by dimension info. One
> workaround
> > is to add dummy dimensions where needed, another is to add two flags, row
> > and col, and set them appropriately. Two flags are needed for backward
> > compatibility, i.e., both false is a traditional array.
> It's possible I could be convinced to like this, but it would take a
> substantial amount of convincing :-). It seems like a pretty big
> violation of orthogonality/"one obvious way"/etc. to have two totally
> different ways of representing row/column vectors.
The '@' operator supports matrix stacks, so it would seem we also need to
support vector stacks. The new addition would only be effective with the
'@' operator. The main problem I see with flags is that adding them would
require an extensive audit of the C code to make sure they were preserved.
Another option, already supported to a large extent, is to have row and col
classes inheriting from ndarray that add nothing, except for a possible new
transpose type function/method. I did mock up such a class just for fun,
and also added a 'dyad' function. If we really don't care to support
stacked vectors we can get by without adding anything.

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