[SciPy-user] scipy.sparse and dot product
Stefan van der Walt
stefan at sun.ac.za
Thu Jul 19 06:33:46 EDT 2007
On Thu, Jul 19, 2007 at 09:34:14AM +0200, lorenzo bolla wrote:
> does this seem weird to you, too?
>
> -----------------------------------------------------------------
>
> In [34]: A = scipy.sparse.spdiags([[1,2,3]],0,3,3)
>
> In [35]: x = scipy.array([1,2,3])
>
> In [36]: scipy.dot(A,x)
> Out[36]:
> array([ (0, 0) 1.0
> (1, 1) 2.0
> (2, 2) 3.0,
> (0, 0) 2.0
> (1, 1) 4.0
> (2, 2) 6.0,
> (0, 0) 3.0
> (1, 1) 6.0
> (2, 2) 9.0], dtype=object) # <--- a matrix with repeated
> entries???
The numpy 'dot'-function does not know about sparse matrices. You
might want to try
A.dot(x) or A*x
I don't think the elementwise-product has been implemented yet.
Regards
Stéfan
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