hadoop-common-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "in.abdul" <in.ab...@gmail.com>
Subject Re: Matrix multiplication in Hadoop
Date Thu, 24 Nov 2011 17:38:37 GMT
Team ,
  i could not able to read sequencial file which cluster gave . Please help
Problem: Sequencial file is returning null

            Thanks and Regards,

On Wed, Nov 23, 2011 at 10:52 AM, Mike Spreitzer [via Lucene] <
ml-node+s472066n3529843h59@n3.nabble.com> wrote:

> I am looking at large dense matrix multiplication as an example problem
> for a class of middleware.  I am also interested in sparse matrices, but
> am taking things one step at a time.
> There is a paper in IEEE CloudCom '10 about Hama, including a matrix
> multiplication technique.  It is essentially the same as what is called
> "technique 4" in the 2009 monograph by John Norstad cited early in this
> thread.  Which means that, despite the fact that Hama touts the virtues of
> BSP (a position with which I am very sympathetic), this technique doesn't
> really take advantage of the extra features that BSP has over MapReduce.
> Note also that this technique creates intermediate data of much greater
> volume than the input.  For example, if each matrix is stored as an NxN
> grid of blocks, the intermediate data (the blocks paired up, awaiting
> multiplication) is a factor of N larger than the input.  I have heard
> people saying that N may be rather larger than sqrt(number of machines)
> because in some circumstances N has to be chosen before the number of
> available machines is known and you want to be able to divide the NxN load
> among your machines rather evenly.  Even if N is like sqrt(number of
> machines) this is still an unwelcome amount of bloat.  In comparison, the
> SUMMA technique does matrix multiplication but its intermediate data
> volume is no greater than the input.
> Thanks,
> Mike
> ------------------------------
>  If you reply to this email, your message will be added to the discussion
> below:
> http://lucene.472066.n3.nabble.com/Matrix-multiplication-in-Hadoop-tp3519089p3529843.html
>  To unsubscribe from Lucene, click here<http://lucene.472066.n3.nabble.com/template/NamlServlet.jtp?macro=unsubscribe_by_code&node=472066&code=aW4uYWJkdWxAZ21haWwuY29tfDQ3MjA2NnwxMDczOTUyNDEw>
> .
> NAML<http://lucene.472066.n3.nabble.com/template/NamlServlet.jtp?macro=macro_viewer&id=instant_html%21nabble%3Aemail.naml&base=nabble.naml.namespaces.BasicNamespace-nabble.view.web.template.NabbleNamespace-nabble.view.web.template.InstantMailNamespace&breadcrumbs=instant+emails%21nabble%3Aemail.naml-instant_emails%21nabble%3Aemail.naml-send_instant_email%21nabble%3Aemail.naml>

View this message in context: http://lucene.472066.n3.nabble.com/Matrix-multiplication-in-Hadoop-tp3519089p3534254.html
Sent from the Hadoop lucene-users mailing list archive at Nabble.com.
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message