//if the process was launched through smpirun script we generate a global mpi_comm_world
//if not, we let MPI_COMM_NULL, and the comm world will be private to each mpi instance
if(smpirun){
//if the process was launched through smpirun script we generate a global mpi_comm_world
//if not, we let MPI_COMM_NULL, and the comm world will be private to each mpi instance
if(smpirun){