[Numpy-discussion] defmatrix.py

Travis Oliphant oliphant@ee.byu....
Mon Mar 26 17:02:02 CDT 2007

> I think that might be the simplest thing, dot overrides subtypes. BTW, 
> here is another ambiguity
> In [6]: dot(array([[1]]),ones(2))
> ---------------------------------------------------------------------------
> exceptions.ValueError                                Traceback (most 
> recent call last)
> /home/charris/<ipython console>
> ValueError: matrices are not aligned
> Note that in this case dot acts like the rhs is always a column vector 
> although it returns a 1-d vector. I don't know that this is a bad 
> thing, but perhaps we should extend this behaviour to matrices, which 
> would be different from the now current 1-d is always a *row* vector, i.e.

The rule 1-d is always a *row* vector only applies when converting to a 

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.


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