MPI Hello World

mpihello.c

#include <mpi.h>
#include <stdio.h>

int main(int argc, char* argv[]) {
  MPI_Init(&argc, &argv);
  
  int rank, size;
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  MPI_Comm_size(MPI_COMM_WORLD, &size);
  
  char name[256];
  // MPI_Get_processor_name(name, sizeof(name));
  gethostname(name,255);
  
  fprintf(stderr, "Hello from %s (%d/%d)\n", name, rank, size);
  
  MPI_Finalize();
}