[Numpy-discussion] Sum of the product of three or more arrays

Geoffrey Zhu zyzhu2000@gmail....
Fri Oct 19 14:48:41 CDT 2007


On 10/18/07, Robert Kern <robert.kern@gmail.com> wrote:
> Geoffrey Zhu wrote:
> > Hi All,
> >
> > Given three vectors of the same lengths, X, Y, and Z, I am looking for
> > an efficient way to calculate the following:
> >
> > sum(x[i]*y[i]*z[i], for i=1..n )
>
> (x*y*z).sum()
>
> --
> Robert Kern
>
> "I have come to believe that the whole world is an enigma, a harmless enigma
>  that is made terrible by our own mad attempt to interpret it as though it had
>  an underlying truth."
>  -- Umberto Eco
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Thanks Robert.

(x*y*z).sum() is probably faster than sum(x*y*z).


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