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  1. library(Rmpi)
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <mpi.h>
  5. #include <limits.h>
  6.  
  7. #define ARRAY_SIZE 8000000
  8. #define RANGE 1000000000
  9.  
  10. int main(int argc, char *argv[]) {
  11.     int rank, size, i;
  12.     int *array = NULL;
  13.     int local_min = INT_MAX;
  14.     int overall_min;
  15.     int segment_size;
  16.  
  17.     MPI_Init(&argc, &argv);
  18.     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  19.     MPI_Comm_size(MPI_COMM_WORLD, &size);
  20.  
  21.     if (size != 8) {
  22.         if (rank == 0) {
  23.             fprintf(stderr, "This program is designed to run with 8 processes.\n");
  24.         }
  25.         MPI_Finalize();
  26.         return 1;
  27.     }
  28.  
  29.     segment_size = ARRAY_SIZE / size;
  30.  
  31.     if (rank == 0) {
  32.         array = (int *)malloc(sizeof(int) * ARRAY_SIZE);
  33.         for (i = 0; i < ARRAY_SIZE; i++) {
  34.             array[i] = rand() % (RANGE + 1);
  35.         }
  36.     }
  37.  
  38.     int *sub_array = (int *)malloc(sizeof(int) * segment_size);
  39.  
  40.     MPI_Bcast(array, ARRAY_SIZE, MPI_INT, 0, MPI_COMM_WORLD);
  41.  
  42.     // Calculate the local minimum
  43.     for (i = 0; i < segment_size; i++) {
  44.         int idx = rank * segment_size + i;
  45.         if (array[idx] < local_min) {
  46.             local_min = array[idx];
  47.         }
  48.     }
  49.  
  50.     // Gather all local minima at root
  51.     MPI_Gather(&local_min, 1, MPI_INT, sub_array, 1, MPI_INT, 0, MPI_COMM_WORLD);
  52.  
  53.     if (rank == 0) {
  54.         overall_min = INT_MAX;
  55.         for (i = 0; i < size; i++) {
  56.             if (sub_array[i] < overall_min) {
  57.                 overall_min = sub_array[i];
  58.             }
  59.         }
  60.  
  61.         // Validate the result by finding the minimum sequentially
  62.         int true_min = INT_MAX;
  63.         for (i = 0; i < ARRAY_SIZE; i++) {
  64.             if (array[i] < true_min) {
  65.                 true_min = array[i];
  66.             }
  67.         }
  68.  
  69.         printf("Overall minimum found by MPI: %d\n", overall_min);
  70.         printf("True minimum found by sequential search: %d\n", true_min);
  71.     }
  72.  
  73.     if (array != NULL) {
  74.         free(array);
  75.     }
  76.     free(sub_array);
  77.  
  78.     MPI_Finalize();
  79.     return 0;
  80. }
  81.  
Success #stdin #stdout #stderr 0.26s 40628KB
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Error in library(Rmpi) : there is no package called ‘Rmpi’
Execution halted
https://ideone.com/CSnnRM
language:
R (R 3.5.2)
created:
13 days ago
visibility:
public

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