[Numpy-discussion] Regarding Matrices
Travis Oliphant
oliphant.travis at ieee.org
Mon Aug 14 16:13:50 CDT 2006
Torgil Svensson wrote:
>>>> import numpy
>>>> numpy.__version__
>>>>
> '1.0b1'
>
>>>> from numpy import *
>>>> A = [1,2,3,4,5,6,7,8,9]
>>>> B = asmatrix(reshape(A,(3,3)))
>>>> B
>>>>
> matrix([[1, 2, 3],
> [4, 5, 6],
> [7, 8, 9]])
>
>>>> B**0
>>>>
> matrix([[ 1., 0., 0.],
> [ 0., 1., 0.],
> [ 0., 0., 1.]])
>
>>>> power(B,0)
>>>>
> matrix([[1, 1, 1],
> [1, 1, 1],
> [1, 1, 1]])
>
> Shouldn't power() and the ** operator return the same result for matrixes?
>
No. power is always the ufunc which does element-by-element raising to
a power. This is actually a feature in that you can use the function
call to do raising to a power without caring what kind of array subclass
is used.
In the same manner, multiply is *always* the ufunc.
-Travis
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