[Numpy-discussion] Binary ufuncs: minimum

Charles R Harris charlesr.harris@gmail....
Tue May 27 15:14:59 CDT 2008


On Tue, May 27, 2008 at 2:10 PM, Travis E. Oliphant <oliphant@enthought.com>
wrote:

> Stéfan van der Walt wrote:
> > Did this change recently?
> >
> > In [33]: np.__version__
> > Out[33]: '1.1.0.dev5211'
> >
> > In [34]: np.minimum(np.uint8(164), np.uint64(12807)).dtype
> > Out[34]: dtype('uint64')
> >
> > But yes, that looks like it should return a uint8.
> >
> This discussion is really moot unless a proposal for how to handle
> different casting rules for different ufuncs is proposed.   Right now,
> the type-promotion rules are generic and do not depend on the ufunc only
> on coercion rules for the mixed types.
>
> One problem with a casting-rules-per-ufunc approach is that it makes it
> harder to add new types and have them fit in to the casting structure
> (which is currently possible now).   Some mechanism for allowing the
> types to plug-in to the per-ufunc rules would be needed.
>
> These are not impossible things, just a bit of work and not on my
> personal priority list.
>

Not everything follows those rules, however. So I have put these things up
for review so that we can agree on what the are. Of particular concern in my
mind are the bitwise and shift operators which currently work in a counter
intuitive manner.

Chuck
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