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Re: Matrix multiplication in Hadoop
Team ,
  i could not able to read sequencial file which cluster gave . Please help
.
Problem: Sequencial file is returning null

            Thanks and Regards,
        S SYED ABDUL KATHER
                9731841519
On Wed, Nov 23, 2011 at 10:52 AM, Mike Spreitzer [via Lucene] <
ml-node+[EMAIL PROTECTED]> 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
>
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THANKS AND REGARDS,
SYED ABDUL KATHER
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