[Numpy-discussion] array of matrices

Bryan Cole bryan@cole.uklinux....
Tue Mar 31 16:10:20 CDT 2009


> 
> I think dot will work, though you'll need to work a little bit to get the 
> answer:
> 
> >>> import numpy as np
> >>> a = np.array([[1,2], [3,4]], np.float)
> >>> aa = np.array([a,a+1,a+2])
> >>> bb = np.array((a*5, a*6, a*7, a*8))
> >>> np.dot(aa, bb).shape
> (3, 2, 4, 2)
> >>> for i, a_ in enumerate(aa): 
> ...     for j, b_ in enumerate(bb):
> ...         print (np.dot(a_, b_) == np.dot(aa, bb)[i,:,j,:]).all()
> ... 
> True
> 

Thanks. Your comment has helped me understand what dot() does for
ndims>2 . It's a pity this will be too memory inefficient for large N.

Bryan

> 




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