[Numpy-discussion] array.sum() slower than expected along some array axes?

[Robert Kern]

Stephen Simmons wrote:

> The question though is whether all of the inner loop's overhead is 
> necessary.
> My counterexample using numpy.dot() suggests there's considerable scope 
> for improvement, at least for certain common cases.

Well, yes. You most likely have an ATLAS-accelerated dot(). The ATLAS put a lot
of work into making matrix products really fast. However, they did so at a cost:
different architectures use different code. That's not really something we can
do in the core of numpy without making numpy as difficult to build as ATLAS is.

-- 
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