[Numpy-discussion] Proposal to make power return float, and other such things.

Robert Kern robert.kern at gmail.com
Tue Feb 18 08:53:40 EST 2014


On Tue, Feb 18, 2014 at 1:46 PM, Nathaniel Smith <njs at pobox.com> wrote:
> On 18 Feb 2014 07:07, "Robert Kern" <robert.kern at gmail.com> wrote:
>>
>> On Tue, Feb 18, 2014 at 12:00 PM, Nathaniel Smith <njs at pobox.com> wrote:
>> > Perhaps integer power should raise an error on negative powers? That way
>> > people will at least be directed to use arr ** -1.0 instead of silently
>> > getting nonsense from arr ** -1.
>>
>> Controllable by np.seterr(invalid=...)? I could get behind that.
>
> I'm not sure the np.seterr part would work or be a good idea, given that we
> have no way to return or propagate NaN... I vote for just an unconditional
> error.

<shrug> We issue configurable warning/error/ignore behavior for
integer 0/0 through this mechanism too without any NaNs. However,
that's `divide` and not `invalid`. Your point is taken that `invalid`
usually implies that a `NaN` is generated, though I don't think this
is ever stated anywhere. I just suggested `invalid` as that is usually
what we use for function domain violations.

-- 
Robert Kern



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