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MyASPN >> Mail Archive >> numpy-discussion
numpy-discussion
Re: [Numpy-discussion] numexpr thoughts
by David M. Cooke other posts by this author
Mar 7 2006 10:53AM messages near this date
Re: [Numpy-discussion] numexpr thoughts | [Numpy-discussion] numexpr
On Tue, Mar 07, 2006 at 11:33:45AM -0700, Tim Hochberg wrote:
>  Tim Hochberg wrote:
>  
>  >>3. Reduction. I figure this could be done at the end of the program in
>  >>  each loop: sum or multiply the output register. Downcasting the
>  >>  output could be done here too.
>  >> 
>  
>  I'm still not excited about summing over the whole output buffer though. 
>  That ends up allocating and scanning through a whole extra buffer which 
>  may result in a signifigant speed and memory hit for large arrays. Since 
>  if we're only doing this on the way out, there should be no problem just 
>  allocating a single double (or complex) to do the sum in.  On the way 
>  in, this could be set to zero or one based on what the last opcode is 
>  (sum or product). Then the SUM opcode could simply do something like:

No, no, we'd just sum over the 128 element output vector (mem[0]), and
add the result to cumulative sum. That vector should already be in
cache, as the last op would put it there.

>  BTW, the cleanup of the interpreter looks pretty slick.

Not finished yet :-) Look for a checkin today (if I have time).

-- 
|> |\/|<
/--------------------------------------------------------------------------|David M. Cooke  
                    http://arbutus.physics.mcmaster.ca/dmc/
|cookedm@[...].ca


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