[Numpy-discussion] Integers to integer powers

[josef.pktd at gmail.com]

On Fri, May 20, 2016 at 4:27 PM, Warren Weckesser <
warren.weckesser at gmail.com> wrote:

>
>
> On Fri, May 20, 2016 at 4:22 PM, Alan Isaac <alan.isaac at gmail.com> wrote:
>
>> On 5/19/2016 11:30 PM, Nathaniel Smith wrote:
>>
>>> the last bad
>>> option IMHO would be that we make int ** (negative int) an error in
>>> all cases, and the error message can suggest that instead of writing
>>>
>>>     np.array(2) ** -2
>>>
>>> they should instead write
>>>
>>>     np.array(2) ** -2.0
>>>
>>> (And similarly for np.int64(2) ** -2 versus np.int64(2) ** -2.0.)
>>>
>>
>>
>>
>> Fwiw, Haskell has three exponentiation operators
>> because of such ambiguities.  I don't use C, but
>> I think the contrasting decision there was to
>> always return a double, which has a clear attraction
>> since for any fixed-width integral type, most of the
>> possible input pairs overflow the type.
>>
>> My core inclination would be to use (what I understand to be)
>> the C convention that integer exponentiation always produces
>> a double, but to support dtype-specific exponentiation with
>> a function.
>
>
>
> C doesn't have an exponentiation operator.  The C math library has pow,
> powf and powl, which (like any C functions) are explicitly typed.
>
> Warren
>
>
>   But this is just a user's perspective.
>>
>> Cheers,
>> Alan Isaac
>>
>>
>> _______________________________________________
>> NumPy-Discussion mailing list
>> NumPy-Discussion at scipy.org
>> https://mail.scipy.org/mailman/listinfo/numpy-discussion
>>
>
>
> _______________________________________________
> NumPy-Discussion mailing list
> NumPy-Discussion at scipy.org
> https://mail.scipy.org/mailman/listinfo/numpy-discussion
>
>

another question

uint are positive so the division problem doesn't show up. So that could
still handle a usecase for ints.

I'm getting stronger in favor of float because raising an exception (or
worse, nonsense) in half of the parameter spaces sounds ...  (maybe kind of
silly)

Josef
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/numpy-discussion/attachments/20160520/0a5515ca/attachment.html>