[Numpy-discussion] vectorizing loops

David Cournapeau david@ar.media.kyoto-u.ac...
Mon Oct 29 22:20:12 CDT 2007

Timothy Hochberg wrote:
> On 10/29/07, *Christopher Barker* <Chris.Barker@noaa.gov 
> <mailto:Chris.Barker@noaa.gov>> wrote:
>     >> (incidently, the kind of things 'we' are doing seem like the most
>     > simple things to JIT).
>     Wouldn't a numpy-aware psyco be cool then?
>     Oh well, I'm not going to write it!
>     (though as I think about it, for the special case of a contiguous
>     array,
>     it would be awfully similar to an array.array --- hmmm.)
> Psyco is aware of array.array and can operate on array.array's quite 
> fast. [In fact, somewhere I have a ndarray-like class based on Psyco 
> that runs pretty fast for integers, but not so fast for floats]. The 
> problem that Psyco has for numeric purposes is that it has no concept 
> of floating point numbers. It can "natively" store only a few 
> different things: ints, pointers, and arrays of ints or pointers. To 
> put, for example, doubles, onto the Psyco stack or into one of it's 
> registers, you need to break the bits of the double up, and stuff them 
> into a couple of different int registers. Then to operate on them you 
> need to put them back together, since they may get separated. All of 
> this adds a fair amount of overhead.
> I've been hoping that the PyPy jit will address this, but I haven't 
> had time to follow that project closely enough to see if that's on the 
> agenda.
My impression is that it is hard to follow pypy when you are not 'part 
of it', but just from the ML, and a couple of questions of mine, my 
understanding is that it is on the agenda. They have a JIT (maybe does 
not work on float, though), there is work on numpy arrays at the rpython 
level (rpython being the typed subset of python pypy is using at their 


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> .   |-\
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> .  tim.hochberg@ieee.org <mailto:tim.hochberg@ieee.org>
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