[Numpy-discussion] matrix indexing question
Fri Mar 30 00:10:50 CDT 2007
On 3/29/07, Timothy Hochberg <email@example.com> wrote:
> On 3/29/07, Bill Baxter <firstname.lastname@example.org> wrote:
> > On 3/30/07, Timothy Hochberg <email@example.com> wrote:
> > > Note, however that you can't (for instance) multiply column vector
> > with
> > > a row vector:
> > >
> > > >>> (c)(r)
> > > Traceback (most recent call last):
> > > ...
> > > TypeError: Cannot matrix multiply columns with anything
> > >
> > That should be allowed. (N,1)*(1,M) is just an (N,M) matrix with
> > entries C[i,j] = A[i,0]*B[0,]
> I thought about that a little, and while I agree that it could be allowed,
> I'm not sure that it should be allowed. It's a trade off between a bit of
> what I would guess is little used functionality with some enhanced error
> checking (I would guess that usually row*column
Make that column*row. Bah. I'm off to bed.
signals a mistake). However, I don't care much one way or the other; it's
> not hard to allow.
> I kind of like the idea of using call for multiply, though. If it
> > doesn't turn out to have any major down sides it could be a good way
> > to give ndarray a concise syntax for "dot".
> We'll see how it goes down this time. I've proposed using call before,
> since I've thought the matrix situation was kind of silly for what seems
> like ages now, but it always sinks without a ripple.
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