pbd-mpi.R

## @knitr pbd-mpi


library(pbdMPI, quiet = TRUE )
init()

myRank <- comm.rank() # comm index starts at 0 , not 1
comm.print(myRank , all.rank=TRUE)
node <- system("cat /etc/hostname", intern = TRUE) # Sys.getenv("HOSTNAME")
if(myRank == 0) {
    comm.print(paste0("hello, world from ", myRank, " ", node), all.rank=TRUE)
} else comm.print(paste0("goodbye from ", myRank, " ", node), all.rank=TRUE)

if(comm.rank() == 0) print(date())
set.seed(myRank)  # see parallel basics tutorial for more on parallel random number generation
N.gbd <- 1e7
X.gbd <- matrix(runif(N.gbd * 2), ncol = 2)
r.gbd <- sum(rowSums(X.gbd^2) <= 1)
ret <- allreduce(c(N.gbd,r.gbd), op = "sum")
PI <- 4 * ret [2] / ret [1]
comm.print(paste0("Pi is roughly: ", PI))
if(comm.rank() == 0) print(date())

finalize()