[SciPy-dev] SciPy improvements

Travis Oliphant oliphant.travis@ieee....
Fri Apr 13 02:06:41 CDT 2007


David Cournapeau wrote:
> I have not given a lot of thoughts about it yet; what matters the most 
> is that all algo have the same conventions. Nevertheless, my experience 
> so far in numpy is similar to yours with regard to ML algorithms (except 
> point 2: depending on the algo. you need contiguous access along one 
> dimension, and my impression is that in numpy, this matters a lot 
> performance wise, at least much more than in matlab).
>   
If I understand you correctly, this is not as true as it once was.   
There was some benchmark code that showed a slow-down on transposed 
arrays until we caught the bug that was causing it.

What is important is that your inner-loops are running over data that is 
"closest" together in memory.   Exactly how close is close enough 
depends on cache size.

-Travis



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