[R-sig-hpc] papply help

[Rowe, Brian Lee Yung (Portfolio Analytics)]

Nathan,

You might want to disclose some detail regarding your environment (e.g.
do you have a working Rmpi installation?) and some (broken) code
samples. This might get the discussion going a bit faster.

Regarding the performance question, you'll find as in most distributed
systems, that performance is highly dependent on your API, including
message size and volume. If you blindly try to parallelize, it will
probably be slower, although a well-designed system will give the
opposite result. Hence, there is no straight answer, but rather the
interminable "it depends".

Cheers,
Brian
 

-----Original Message-----
From: r-sig-hpc-bounces at r-project.org
[mailto:r-sig-hpc-bounces at r-project.org] On Behalf Of Nathan S.
Watson-Haigh
Sent: Monday, May 18, 2009 10:17 PM
To: R-sig-hpc at r-project.org
Subject: [R-sig-hpc] papply help


* PGP Signed by an unknown key: 05/18/2009 at 10:17:16 PM

I have some code that simply takes a matrix and raises all the values to
a given
power:

<code>
m <- matrix(0.8, 10, 10)
beta <- 6
m <- m^beta
</code>

I'd like to parallelise this so that each slave executes the calculation
on each
of the rows from the matrix. Would this yield any speedup given than my
matrix
could be a 10,000 - 15,000 square?

The papply library/function seems like just the trick, but I can't seem
to get
it to work....maybe the docs are confusing me as I'm not sure what the
different
arguments are actually doing!

Any pointers welcomed :o)
Nathan

--
--------------------------------------------------------
Dr. Nathan S. Watson-Haigh
OCE Post Doctoral Fellow
CSIRO Livestock Industries
Queensland Bioscience Precinct
St Lucia, QLD 4067
Australia

Tel: +61 (0)7 3214 2922
Fax: +61 (0)7 3214 2900
Web: http://www.csiro.au/people/Nathan.Watson-Haigh.html
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* 0x063354BE (L)


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