Hi, With a naive parallelism approach (on $i and $j), I think it's possible to bring it down to O(N) with a constant cost (in dollars), assuming "full cloud elasticity" (i.e., the number of instances that can be triggered up is not the bottleneck).
The 28.io platform should supports this (disclaimer: it's my employer). Kind regards, Ghislain On 03 Feb 2014, at 12:30, jean-marc Mercier <[email protected]> wrote: > Hi all, > > I've tried the following JSON query with zorba, mimicking a NxN, with N=200, > matrix multiplications. Time is 10 sec on http://try.zorba.io/, behaving with > a cubic N^3 complexitity. > Do you really want to know what are the performances of standard linear > algebra library for such matrix multiplications ? > > > > > import module namespace datetime = > "http://www.zorba-xquery.com/modules/datetime";; > > declare variable $size := 200; > > declare variable $A := [ for $i in 1 to $size return > [ > for $j in 1 to $size return $i*$size+$j > ] > ]; > > let $R := ( datetime:current-time(), > [ > for $i in 1 to count(jn:members($A)) return > [ > for $k in 1 to count(jn:members($A)) return > fn:sum( > for $j in 1 to count(jn:members($A)) return > $A($i)($j) * $A($j)($k) > ) > ] > ] > , datetime:current-time() ) > > return $R[count($R)] - $R[1] > > > 2014-02-03 David Carlisle <[email protected]>: > On 03/02/2014 10:56, Hermann Stamm-Wilbrandt wrote: > PT1.713634S (JSONiq) versus PT9.77805S (XQuery) > > > ooh interesting , I wonder where the bottleneck in the xquery is. > Probably as Michael commented at some point earlier in the thread, the > time to access the ith element of a sequence $a[$i]. > > > But the language doesn't _need_ to change, just if more people did it > the xquery compilers would perhaps look out for sequences that are > exclusively accessed via numeric filters and implement them in a way > that gives constant time access. Having a separate array type does give > them a big hint though:-) > > David > > > ________________________________________________________________________ > The Numerical Algorithms Group Ltd is a company registered in England > and Wales with company number 1249803. The registered office is: > Wilkinson House, Jordan Hill Road, Oxford OX2 8DR, United Kingdom. > > This e-mail has been scanned for all viruses by Star. The service is > powered by MessageLabs. > ________________________________________________________________________ > _______________________________________________ > [email protected] > http://x-query.com/mailman/listinfo/talk > > _______________________________________________ > [email protected] > http://x-query.com/mailman/listinfo/talk _______________________________________________ [email protected] http://x-query.com/mailman/listinfo/talk
