I'm running a small programme as a test and to learn how to use Rmpi.

I send a data set and routine to two slave nodes, and then get the answers back in an object.  The routines executed are Bayesian Gibbs sampling routines so I would expect slightly different answers back from the two nodes but I get identical answers back from both nodes.

I'm under the impression that each node does the complete routine from start to finish before returning answers but this may be my misunderstanding.  Should the answers in fact be identical because mpi has split the job up between the two nodes and both contributed to the calculations, therefore both end up with the same answer?

mpi code that gives me these results is :

  ## send the data to slaves
  mpi.bcast.Robj2slave(sim.dat$bsiaic.dat)
  mpi.bcast.Robj2slave(sim.dat$bsdaic.dat)

  ## send the jags fitting functions to slaves
  mpi.bcast.Robj2slave(bsiaicresults)
  mpi.bcast.Robj2slave(bsdaicresults)

  ## execute the fitting functions on slaves and
  ## get results back
  bsiaictot <- mpi.remote.exec(bsiaicresults())
  bsdaictot <- mpi.remote.exec(bsdaicresults())


Any suggestions?

Thanks

J

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Dr. Jim Maas
University of East Anglia

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