[Numpy-discussion] Extending ufunc signature syntax for matmul, frozen dimensions

[Hameer Abbasi]

I agree with Eric here. As one of the users of __array_ufunc__, I'd
much rather have three separate gufuncs or a single one with axis
insertion and removal. On 30/04/2018 at 23:38, Eric wrote: I think I’m
-1 on this - this just makes things harder on the implementers of
_array_ufunc__ who now might have to work out which signature matches.
I’d prefer the solution where np.matmul is a wrapper around one of
three gufuncs (or maybe just around one with axis insertion) - this is
similar to how np.linalg already works. Eric On Mon, 30 Apr 2018 at
14:34 Stephan Hoyer <shoyer at gmail.com> wrote: On Sun, Apr 29, 2018 at
2:48 AM Matti Picus <matti.picus at gmail.com> wrote: The proposed
solution to issue #9029 is to extend the meaning of a signature so
"syntax like (n?,k),(k,m?)->(n?,m?) could mean that n and m are
optional dimensions; if missing in the input, they're treated as 1,
and then dropped from the output" I agree that this is an elegant fix
for matmul, but are there other use-cases for "optional dimensions" in
gufuncs? It feels a little wrong to add gufunc features if we can only
think of one function that can use them.
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