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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include < mpi.h>
  4. int main(int argc, char **argv)
  5. {
  6.     int rank, size, i, j, n, 
  7.  
  8.     // Initialize MPI
  9.     MPI_Init(&argc, &argv);
  10.     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  11.     MPI_Comm_size(MPI_COMM_WORLD, &size);
  12.  
  13.     // Take input for n
  14.     if (rank == 0)
  15.     {
  16.         printf("Enter the value of n (must be divisible by p): ");
  17.         scanf_s("%d", &n);
  18.     }
  19.  
  20.     // Broadcast n to all processes
  21.     MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
  22.  
  23.     // Take input for p
  24.     if (rank == 0)
  25.     {
  26.         printf("Enter the value of p (must be smaller than n): ");
  27.         scanf_s("%d", &p);
  28.     }
  29.  
  30.     // Broadcast p to all processes
  31.     MPI_Bcast(&p, 1, MPI_INT, 0, MPI_COMM_WORLD);
  32.  
  33.     // Error handling for p and n
  34.     if (n % p != 0)
  35.     {
  36.         if (rank == 0)
  37.             printf("Error: n must be divisible by p.\n");
  38.         MPI_Finalize();
  39.         return 0;
  40.     }
  41.  
  42.     if (p >= n)
  43.     {
  44.         if (rank == 0)
  45.             printf("Error: p must be smaller than n.\n");
  46.         MPI_Finalize();
  47.         return 0;
  48.     }
  49.  
  50.     // Define matrices and vectors dynamically
  51.     int *A = (int *)malloc(sizeof(int) * n * n);
  52.     int *x = (int *)malloc(sizeof(int) * n);
  53.     int *y = (int *)malloc(sizeof(int) * n);
  54.     int *local_A = (int *)malloc(sizeof(int) * (n / p) * n);
  55.     int *local_x = (int *)malloc(sizeof(int) * (n / p));
  56.     int *local_y = (int *)malloc(sizeof(int) * (n / p));
  57.  
  58.     // Initialize matrices and vectors with random values
  59.     if (rank == 0)
  60.     {
  61.         printf("\nMatrix A:\n");
  62.         for (i = 0; i < n * n; i++)
  63.         {
  64.             A[i] = rand() % 101; // random integer between 0 and 100
  65.             printf("%d\t", A[i]);
  66.             if ((i + 1) % n == 0)
  67.                 printf("\n");
  68.         }
  69.  
  70.         printf("\nVector x:\n");
  71.         for (i = 0; i < n; i++)
  72.         {
  73.             x[i] = rand() % 101; // random integer between 0 and 100
  74.             printf("%d\n", x[i]);
  75.         }
  76.     }
  77.  
  78.     // Broadcast matrices and vectors to all processes
  79.     MPI_Bcast(A, n * n, MPI_INT, 0, MPI_COMM_WORLD);
  80.     MPI_Bcast(x, n, MPI_INT, 0, MPI_COMM_WORLD);
  81.  
  82.     // Calculate the local size for each process
  83.     int local_n = n / size;
  84.  
  85.     // Scatter matrix A to all processes
  86.     MPI_Scatter(A, local_n * n, MPI_INT, local_A, local_n * n, MPI_INT, 0, MPI_COMM_WORLD);
  87.  
  88.     // Scatter vector x to all processes
  89.     MPI_Scatter(x, local_n, MPI_INT, local_x, local_n, MPI_INT, 0, MPI_COMM_WORLD);
  90.  
  91.     // Compute local vector elements
  92.     for (i = 0; i < local_n; i++)
  93.     {
  94.         local_y[i] = 0;
  95.         for (j = 0; j < n; j++)
  96.         {
  97.             local_y[i] += local_A[i * n + j] * local_x[j];
  98.         }
  99.     }
  100.  
  101.     // Gather local results back to process 0
  102.     MPI_Gather(local_y, local_n, MPI_INT, y, local_n, MPI_INT, 0, MPI_COMM_WORLD);
  103.  
  104.     // Process 0 prints the result
  105.     if (rank == 0)
  106.     {
  107.         printf("\nResultant Vector y:\n");
  108.         for (i = 0; i < n; i++)
  109.         {
  110.             printf("y[%d] = %d\n", i, y[i]);
  111.         }
  112.     }
  113.  
  114.     // Free dynamically allocated memory
  115.     free(A);
  116.     free(x);
  117.     free(y);
  118.     free(local_A);
  119.     free(local_x);
  120.     free(local_y);
  121.  
  122.     // Finalize MPI
  123.     MPI_Finalize();
  124.  
  125.     return 0;
  126. }
Success #stdin #stdout #stderr 0.28s 40728KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
stderr 
Error: unexpected symbol in "int main"
Execution halted
https://ideone.com/3G4DzH
language:
R (R 3.5.2)
created:
25 days ago
visibility:
public

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