[Numpy-discussion] Integers to integer powers, let's make a decision

[Peter Creasey]

>
> +1
>
> On Sat, Jun 4, 2016 at 10:22 AM, Charles R Harris
> <charlesr.harris at gmail.com> wrote:
>> Hi All,
>>
>> I've made a new post so that we can make an explicit decision. AFAICT, the
>> two proposals are
>>
>> Integers to negative integer powers raise an error.
>> Integers to integer powers always results in floats.
>>
>> My own sense is that 1. would be closest to current behavior and using a
>> float exponential when a float is wanted is an explicit way to indicate that
>> desire. OTOH, 2. would be the most convenient default for everyday numerical
>> computation, but I think would more likely break current code. I am going to
>> come down on the side of 1., which I don't think should cause too many
>> problems if we start with a {Future, Deprecation}Warning explaining the
>> workaround.
>>
>> Chuck
>>


+1 (grudgingly)

My thoughts on this are:
(i) Intuitive APIs are better, and power(a,b) suggests to a lot of
(most?) readers that you are going to invoke a function like the C
pow(double x, double y) on every element. Doing positive integer
powers with the same function name suggests a correspondence that is
in practice not that helpful. With a time machine I’d suggest a
separate function for positive integer powers, however...
(ii) I think that ship has sailed, and particularly with e.g. a**3 the
numpy conventions are backed up by quite a bit of code, probably too
much to change without a lot of problems. So I’d go with integer ^
negative integer is an error.

Peter