[Numpy-discussion] defmatrix.py

Travis Oliphant oliphant@ee.byu....
Mon Mar 26 17:36:59 CDT 2007


Charles R Harris wrote:

>
>
>     The rule 1-d is always a *row* vector only applies when converting
>     to a
>     matrix.
>
>     In this case, the dot operator does not "convert to a matrix" but
>     uses
>     rules for operating with mixed 2-d and 1-d arrays inherited from
>     Numeric.
>
>     I'm very hesitant to change those rules.
>
>
> I wasn't suggesting that, just noticing that the rule was 1-d vector 
> on right is treated as a column vector by dot, which is why an 
> exception was raised in the posted case. If it is traditional for 
> matrix routines always treat is as a row vector, so be it.

O.K.  So, the problem is that when I defined matrix multiplication, I 
mistakenly believed that dot always interpreted 1-d arrays as row 
vectors which it is now clear it doesn't.

I think this led to the issues. 

So, making dot always return arrays seems like the needed fix.

-Travis





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