[Numpy-discussion] A basic question on the dot function

Bill Baxter wbaxter@gmail....
Tue Oct 16 13:20:49 CDT 2007


On 10/17/07, Julien Hillairet <julien.hillairet@gmail.com> wrote:
> Hello,
>
>
> First of all, I'm sorry if this question had already been asked. I've
> searched on the gmane archive and elsewhere on internet, but I didn't found
> the answer to my question.
>
> As expected, the dot product of 2 'classical' vectors works fine :
>
> In [50]: a0 = numpy.array([1,2,3])
> In [51]: numpy.dot(a0,a0)
> Out[51]: 14
>
> What I don't understand, is why the dot product of a (3,N) vector gives an
> error :

dot() also serves as Numpy's matrix multiply function.  So it's trying
to interpret that as a (3,N) matrix times a (3,N) matrix.

See examples here:
http://www.scipy.org/Numpy_Example_List_With_Doc#head-2a810f7dccd3f7c700d1076f15078ad1fe3c6d0d

--bb


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