MPI C++

Hello World

//
//  hello_mpi.cpp: display a message on the screen
//
#include <iostream>
#include <mpi.h>
 
int main (int argc, char *argv[]) {
  // Initialize
  MPI::Init(argc, argv);
 
  // get myid and # of processors 
  int numproc = MPI::COMM_WORLD.Get_size();
  int myid = MPI::COMM_WORLD.Get_rank();
 
  std::cout << "hello from " << myid << std::endl;
 
  // wait until all processors come here 
  MPI::COMM_WORLD.Barrier();
 
  if ( myid == 0 ) {
    // only myid = 0 do this
    std::cout << numproc << " processors said hello!" << std::endl;
  }
 
  MPI::Finalize();
}

Compile

mpiCC hello_mpi.cpp

Example of Jobscript

​See Example