double *v = (double*)malloc(sizeof(double)*n);
if (mpi_rank == 0) {
    init_random_vector(n, v);
}
// n is the number of data items
int elements_per_proc = n/mpi_p;
double *sub_v = (double*)malloc(sizeof(double)*elements_per_proc);

if (mpi_rank == 0) {
    //insertion_sort(n, v);
    MPI_SCATTER(v, elements_per_proc, MPI_DOUBLE, sub_v,
        elements_per_proc, MPI_DOUBLE, 0, MPI_COMM_WORLD);
}