[Numpy-discussion] vectorizing loops

Mathew Yeates myeates@jpl.nasa....
Tue Oct 30 19:06:25 CDT 2007

Thanks all for your suggestions. I see it brought up a lot of 
interesting asides. But my loop was simple enough that I was able to 
figure it out.

I also took a look at NumExpr. While it wasn't something I needed for 
vectorizing, it still looks very interesting. What kinds of performance 
improvements would be expected using this?


Sebastian Haase wrote:
> On 10/26/07, David Cournapeau <david@ar.media.kyoto-u.ac.jp> wrote:
>> P.S: IMHO, this is one of the main limitation of numpy (or any language
>> using arrays for speed; and this is really difficult to optimize: you
>> need compilation, JIT or similar to solve those efficiently).
> This is where the scipy - sandbox numexpr  project comes in
> - if I'm not misaken ....
> http://www.scipy.org/SciPyPackages/NumExpr
> Description
> The scipy.sandbox.numexpr package supplies routines for the fast
> evaluation of array expressions elementwise by using a vector-based
> virtual machine. It's comparable to scipy.weave.blitz (in Weave), but
> doesn't require a separate compile step of C or C++ code.
> I hope that more noise around this  will result  in more interest and
> subsequentially result in more support.
> I think numexpr  might be one of the most powerful ideas in numpy /
> scipy  "recently".
> Did you know about numexpr - David ?
> Cheers,
> Sebastian Haase
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