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

[Forrest Sheng Bao]

Oh yeah, my bad. Forget about it. I guess I was too tired.

Cheers, Forrest

On Sat, Apr 16, 2011 at 10:47 PM, Nathaniel Smith <njs at pobox.com> wrote:

> 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
>
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