float *rand_nums = NULL;

rand_nums = create_rand_nums(num_elements_per_proc);

​

// Sum the numbers locally

float local_sum = 0;

int i;

for (i = 0; i < num_elements_per_proc; i++) {

  local_sum += rand_nums[i];

}

​

// Print the random numbers on each process

printf("Local sum for process %d - %f, avg = %f\n",

       world_rank, local_sum, local_sum / num_elements_per_proc);

​

// Reduce all of the local sums into the global sum

float global_sum;

MPI_Reduce(&local_sum, &global_sum, 1, MPI_FLOAT, MPI_SUM, 0,

           MPI_COMM_WORLD);

​

// Print the result

if (world_rank == 0) {

  printf("Total sum = %f, avg = %f\n", global_sum,

         global_sum / (world_size * num_elements_per_proc));

}

​