[Numpy-discussion] Optimized sum of squares
Sturla Molden
sturla@molden...
Sun Oct 18 13:16:34 CDT 2009
Skipper Seabold skrev:
> I'm curious about this as I use ss, which is just np.sum(a*a, axis),
> in statsmodels and didn't much think about it.
>
> Do the number of loops matter in the timings and is dot always faster
> even without the blas dot?
>
The thing is that a*a returns a temporary array with the same shape as
a, and then that is passed to np.sum. The BLAS dot product don't need to
allocate and deallocate temporary arrays.
S.M.
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