Re: [Numpy-discussion] Integers to negative integer powers, time for a decision.

[V. Armando Sole]

Hi all,

Just to have the options clear. Is the operator '**' going to be handled 
in any different manner than pow?


Thanks.

Armando
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Re: [Numpy-discussion] Integers to negative integer powers, time for a decision.

[Alan Isaac]

On 10/7/2016 9:12 PM, Charles R Harris wrote:

*Always return a float *
/Pluses/
  * Computational convenience



Is the behavior of C++11 of any relevance to the choice?
http://www.cplusplus.com/reference/cmath/pow/

Alan Isaac

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Re: [Numpy-discussion] Integers to negative integer powers, time for a decision.

[josef . pktd]

On Fri, Oct 7, 2016 at 9:12 PM, Charles R Harris
 wrote:
> Hi All,
>
> The time for NumPy 1.12.0 approaches and I like to have a final decision on
> the treatment of integers to negative integer powers with the `**` operator.
> The two alternatives looked to be
>
> Raise an error for arrays and numpy scalars, including 1 and -1 to negative
> powers.
>
> Pluses
>
> Backward compatible
> Allows common powers to be integer, e.g., arange(3)**2
> Consistent with inplace operators
> Fixes current wrong behavior.
> Preserves type
>
>
> Minuses
>
> Integer overflow
> Computational inconvenience
> Inconsistent with Python integers
>
>
> Always return a float
>
> Pluses
>
> Computational convenience
>
>
> Minuses
>
> Loss of type
> Possible backward incompatibilities
> Not applicable to inplace operators
>
>
>
> Thoughts?

2: +1
I'm still in favor of number 2: less buggy code and less mental
gymnastics (watch out for that int, or which int do I need)

(upcasting is not applicable for any inplace operators, AFAIU   *=0.5 ?
zz = np.arange(5)
zz**(-1)
zz *= 0.5

tried in
>>> np.__version__
'1.9.2rc1'
>>> np.__version__
'1.10.4'
backwards compatibility ?
)


Josef


>
> Chuck
>
>
>
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[Numpy-discussion] Integers to negative integer powers, time for a decision.

[Charles R Harris]

Hi All,

The time for NumPy 1.12.0 approaches and I like to have a final decision on
the treatment of integers to negative integer powers with the `**`
operator. The two alternatives looked to be


*Raise an error for arrays and numpy scalars, including 1 and -1 to
negative powers.*
*Pluses*

   - Backward compatible
   - Allows common powers to be integer, e.g., arange(3)**2
   - Consistent with inplace operators
   - Fixes current wrong behavior.
   - Preserves type


*Minuses*

   - Integer overflow
   - Computational inconvenience
   - Inconsistent with Python integers


*Always return a float *

*Pluses*

   - Computational convenience


*Minuses*

   - Loss of type
   - Possible backward incompatibilities
   - Not applicable to inplace operators



Thoughts?

Chuck
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