(-1)**1000

ast nomail at invalid.com
Wed Oct 22 11:27:06 CEST 2014


"Chris Angelico" <rosuav at gmail.com> a écrit dans le message de 
news:mailman.15058.1413968065.18130.python-list at python.org...
> On Wed, Oct 22, 2014 at 7:27 PM, ast <nomail at invalid.com> wrote:
>> If i am writing (-1)**1000 on a python program, will the
>> interpreter do (-1)*(-1)*...*(-1) or something clever ?
>>
>> In fact i have (-1)**N with N an integer potentially big.
>
> Exponentiation is far more efficient than the naive implementation of
> iterated multiplication.

In the very particular case of (-1)**N,  I belive that Python check
the odd or even parity of N and provides the result accordingly.

I tried:
>>> (-1)**1000000000000000000000000000000000
1
>>> (-1)**1000000000000000000000000000000001
-1

and it is instantaneous





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