[Numpy-discussion] ENH: compute many inner products quickly

[Sebastian Berg]

On So, 2016-06-05 at 19:20 -0600, Charles R Harris wrote:
> 
> 
> On Sun, Jun 5, 2016 at 6:41 PM, Stephan Hoyer <shoyer at gmail.com>
> wrote:
> > If possible, I'd love to add new functions for "generalized ufunc"
> > linear algebra, and then deprecate (or at least discourage) using
> > the older versions with inferior broadcasting rules. Adding a new
> > keyword arg means we'll be stuck with an awkward API for a long
> > time to come.
> > 
> > There are three types of matrix/vector products for which ufuncs
> > would be nice:
> > 1. matrix-matrix product (covered by matmul)
> > 2. matrix-vector product
> > 3. vector-vector (inner) product
> > 
> > It's straightful to implement either of the later two options by
> > inserting dummy dimensions and then calling matmul, but that's a
> > pretty awkward API, especially for inner products. Unfortunately,
> > we already use the two most obvious one word names for vector inner
> > products (inner and dot). But on the other hand, one word names are
> > not very descriptive, and the short name "dot" probably mostly
> > exists because of the lack of an infix operator.
> > 
> > So I'll start by throwing out some potential new names:
> > 
> > For matrix-vector products:
> > matvecmul (if it's worth making a new operator)
> > 
> > For inner products:
> > vecmul (similar to matmul, but probably too ambiguous)
> > dot_product
> > inner_prod
> > inner_product
> > 
> I was using mulmatvec, mulvecmat, mulvecvec back when I was looking
> at this. I suppose the mul could also go in the middle, or maybe
> change it to x and put it in the middle: matxvec, vecxmat, vecxvec.
> 

Were not some of this part of the gufunc linalg functions and we just
removed it because we were not sure about the API? Not sure anymore,
but might be worth to have a look.

- Sebastian


> Chuck  
> 
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