MPI_Comm_size(MPI_COMM_WORLD, &size); /* Get nr of tasks */
MPI_Comm_rank(MPI_COMM_WORLD, &rank); /* Get id of this process */
MPI_Comm_size(MPI_COMM_WORLD, &size); /* Get nr of tasks */
MPI_Comm_rank(MPI_COMM_WORLD, &rank); /* Get id of this process */