[Numpy-discussion] an array become a matrix after an element assignment

[Nathaniel Smith]

On Sat, Apr 16, 2011 at 8:39 PM, Forrest Sheng Bao
<forrest.bao at gmail.com> wrote:
>>>> a=zeros((3,3)) + eye(3)
>>>> a*a
> array([[ 1.,  0.,  0.],
>        [ 0.,  1.,  0.],
>        [ 0.,  0.,  1.]])
>
> Then i assigned a value to one of the element:
>
>>>> a[1,2]=4
>
> Finally, the '*' operator was interpreted as a matrix multiplication
>
>>>> a*a
> array([[  1.,   0.,   0.],
>        [  0.,   1.,  16.],
>        [  0.,   0.,   1.]])

That looks like element-wise multiplication to me? (Matrix
multiplication would have given you an 8 where you have a 16.)

-- Nathaniel