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  1. #include <mpi.h>
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4.  
  5. #define MATRIX_SIZE 1024  // Change this to 64, 128, 256, 512, 1024 as needed
  6.  
  7. void matrix_multiply(int *A, int *B, int *C, int size) {
  8.     int i, j, k;
  9.     for (i = 0; i < size; i++) {
  10.         for (j = 0; j < size; j++) {
  11.             C[i * size + j] = 0;
  12.             for (k = 0; k < size; k++) {
  13.                 C[i * size + j] += A[i * size + k] * B[k * size + j];
  14.             }
  15.         }
  16.     }
  17. }
  18.  
  19. int main(int argc, char *argv[]) {
  20.     int rank, size;
  21.     int nrows_per_proc;
  22.     int *A, *B, *C, *local_A, *local_C;
  23.     int i, j;
  24.  
  25.     MPI_Init(&argc, &argv);
  26.     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  27.     MPI_Comm_size(MPI_COMM_WORLD, &size);
  28.  
  29.     // Determine the number of rows per processor
  30.     nrows_per_proc = MATRIX_SIZE / size;
  31.  
  32.     // Allocate memory for matrices
  33.     if (rank == 0) {
  34.         A = (int *)malloc(MATRIX_SIZE * MATRIX_SIZE * sizeof(int));
  35.         B = (int *)malloc(MATRIX_SIZE * MATRIX_SIZE * sizeof(int));
  36.         C = (int *)malloc(MATRIX_SIZE * MATRIX_SIZE * sizeof(int));
  37.  
  38.         // Initialize matrices A and B with random values
  39.         for (i = 0; i < MATRIX_SIZE; i++) {
  40.             for (j = 0; j < MATRIX_SIZE; j++) {
  41.                 A[i * MATRIX_SIZE + j] = rand() % 10;
  42.                 B[i * MATRIX_SIZE + j] = rand() % 10;
  43.             }
  44.         }
  45.     }
  46.  
  47.     // Allocate memory for local matrices
  48.     local_A = (int *)malloc(nrows_per_proc * MATRIX_SIZE * sizeof(int));
  49.     local_C = (int *)malloc(nrows_per_proc * MATRIX_SIZE * sizeof(int));
  50.     B = (int *)malloc(MATRIX_SIZE * MATRIX_SIZE * sizeof(int));  // Each process needs the entire matrix B
  51.  
  52.     // Scatter rows of A to different processes
  53.     MPI_Scatter(A, nrows_per_proc * MATRIX_SIZE, MPI_INT, local_A, nrows_per_proc * MATRIX_SIZE, MPI_INT, 0, MPI_COMM_WORLD);
  54.  
  55.     // Broadcast matrix B to all processes
  56.     MPI_Bcast(B, MATRIX_SIZE * MATRIX_SIZE, MPI_INT, 0, MPI_COMM_WORLD);
  57.  
  58.     // Perform local matrix multiplication
  59.     for (i = 0; i < nrows_per_proc; i++) {
  60.         for (j = 0; j < MATRIX_SIZE; j++) {
  61.             local_C[i * MATRIX_SIZE + j] = 0;
  62.             for (int k = 0; k < MATRIX_SIZE; k++) {
  63.                 local_C[i * MATRIX_SIZE + j] += local_A[i * MATRIX_SIZE + k] * B[k * MATRIX_SIZE + j];
  64.             }
  65.         }
  66.     }
  67.  
  68.     // Gather the result matrix C from all processes
  69.     MPI_Gather(local_C, nrows_per_proc * MATRIX_SIZE, MPI_INT, C, nrows_per_proc * MATRIX_SIZE, MPI_INT, 0, MPI_COMM_WORLD);
  70.  
  71.     // Print result if necessary
  72.     if (rank == 0) {
  73.         printf("Result Matrix C (Showing first 5x5):\n");
  74.         for (i = 0; i < 5; i++) {
  75.             for (j = 0; j < 5; j++) {
  76.                 printf("%d ", C[i * MATRIX_SIZE + j]);
  77.             }
  78.             printf("\n");
  79.         }
  80.     }
  81.  
  82.     // Clean up memory
  83.     if (rank == 0) {
  84.         free(A);
  85.         free(B);
  86.         free(C);
  87.     }
  88.     free(local_A);
  89.     free(local_C);
  90.  
  91.     MPI_Finalize();
  92.     return 0;
  93. }
  94.  
  95.  
  96.  
  97.  
  98.  
Success #stdin #stdout #stderr 0.23s 40676KB
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stdin
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1233 234
stdout
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Standard output is empty
stderr
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Error: unexpected symbol in "void matrix_multiply"
Execution halted
https://ideone.com/LMhob6
language:
R (R 3.5.2)
created:
2 days ago
visibility:
public

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