[Numpy-discussion] exponentiation q.

Keith Goodman kwgoodman@gmail....
Fri Jul 25 15:33:34 CDT 2008


On Fri, Jul 25, 2008 at 1:32 PM, Keith Goodman <kwgoodman@gmail.com> wrote:
> On Fri, Jul 25, 2008 at 1:24 PM, Gideon Simpson <grs2103@columbia.edu> wrote:
>> How does python (or numpy/scipy) do exponentiation?  If I do x**p,
>> where p is some positive integer, will it compute x*x*...*x (p times),
>> or will it use logarithms?
>
> Here are some examples:
>
>>> np.array([[1,2], [3,4]])**2
>
> array([[ 1,  4],
>       [ 9, 16]])
>
>>> np.matrix([[1,2], [3,4]])**2
>
> matrix([[ 7, 10],
>        [15, 22]])
>
>>> np.power(np.matrix([[1,2], [3,4]]), 2)
>
> matrix([[ 1,  4],
>        [ 9, 16]])

Sorry. I see now you're worried about under/overflow.


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