[Numpy-discussion] Changes to the generalized functions.

[Charles R Harris]

On Tue, Sep 23, 2014 at 4:59 PM, Charles R Harris <charlesr.harris at gmail.com
> wrote:

> Hi All,
>
> The question has come up as the whether of not to treat the new gufunc
> behavior as a bug fix, keeping the old constructor name, or have a
> different constructor. Keeping the name makes life easier as we don't need
> to edit the code where numpy currently uses gufuncs, but is risky if some
> third party depends on the old behavior. The gufuncs have been part of
> numpy since the 1.3 release, and google doesn't turn up any uses that I can
> see apart from repeats of numpy code. We can also make fixes if needed
> during the 1.10 beta release cycle. Even so, it is a bit of a risk. To
> spread the blame, if any, please weigh in on the following.
>
>
>    1. Yes, it is a bug, keep the current name and fix the behavior.
>    2. No, we need to be conservative and use a new function.
>
> To clarify the changes. Currently, if an input array does not have as many
dimensions as indicated by the signature, it is filled out with ones to
match the signature as well as broadcasting to the other array. It is also
the case that if a dimension in the signature is 1, then it is broadcast
with the data in the other signature. That is, the parts identified in the
signature are treated as little arrays. The proposed change is to require
that the inputs have at least as many dimensions as the signature and that
dimensions of 1 are not broadcast. That is, the parts identified in the
signature are treated as vectors or matrices rather than little arrays.

Chuck
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