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  1. #include <mpi.h>
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <time.h>
  5.  
  6. int main(int argc, char* argv[]) {
  7.     int N = atoi(argv[1]);  // Matrix size from command line
  8.     int rank, size;
  9.     MPI_Init(&argc, &argv);
  10.     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  11.     MPI_Comm_size(MPI_COMM_WORLD, &size);
  12.  
  13.     double *A, *B, *C_seq, *C_par;
  14.     if (rank == 0) {
  15.         A = (double*)malloc(N * N * sizeof(double));
  16.         B = (double*)malloc(N * N * sizeof(double));
  17.         C_seq = (double*)malloc(N * N * sizeof(double));
  18.         C_par = (double*)malloc(N * N * sizeof(double));
  19.  
  20.         // Initialize matrices A and B with values for testing
  21.         for (int i = 0; i < N * N; i++) {
  22.             A[i] = 1.0;
  23.             B[i] = 1.0;
  24.         }
  25.  
  26.         // Sequential matrix multiplication
  27.         clock_t start_seq = clock();
  28.         for (int i = 0; i < N; i++) {
  29.             for (int j = 0; j < N; j++) {
  30.                 C_seq[i * N + j] = 0;
  31.                 for (int k = 0; k < N; k++) {
  32.                     C_seq[i * N + j] += A[i * N + k] * B[k * N + j];
  33.                 }
  34.             }
  35.         }
  36.         clock_t end_seq = clock();
  37.         double time_seq = (double)(end_seq - start_seq) / CLOCKS_PER_SEC;
  38.         printf("Sequential time for %d x %d matrix: %f seconds\n", N, N, time_seq);
  39.     }
  40.  
  41.     // Parallel matrix multiplication
  42.     int rowsPerProcess = N / size;
  43.     double *localA = (double*)malloc(rowsPerProcess * N * sizeof(double));
  44.     double *localC = (double*)malloc(rowsPerProcess * N * sizeof(double));
  45.  
  46.     MPI_Scatter(A, rowsPerProcess * N, MPI_DOUBLE, localA, rowsPerProcess * N, MPI_DOUBLE, 0, MPI_COMM_WORLD);
  47.     MPI_Bcast(B, N * N, MPI_DOUBLE, 0, MPI_COMM_WORLD);
  48.  
  49.     double start_par = MPI_Wtime();
  50.     for (int i = 0; i < rowsPerProcess; i++) {
  51.         for (int j = 0; j < N; j++) {
  52.             localC[i * N + j] = 0;
  53.             for (int k = 0; k < N; k++) {
  54.                 localC[i * N + j] += localA[i * N + k] * B[k * N + j];
  55.             }
  56.         }
  57.     }
  58.     double end_par = MPI_Wtime();
  59.     double localTime = end_par - start_par;
  60.  
  61.     double maxTime;
  62.     MPI_Reduce(&localTime, &maxTime, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
  63.  
  64.     MPI_Gather(localC, rowsPerProcess * N, MPI_DOUBLE, C_par, rowsPerProcess * N, MPI_DOUBLE, 0, MPI_COMM_WORLD);
  65.  
  66.     if (rank == 0) {
  67.         printf("Parallel time for %d x %d matrix with %d processors: %f seconds\n", N, N, size, maxTime);
  68.  
  69.         // Calculate speedup and efficiency
  70.         double speedup = time_seq / maxTime;
  71.         double efficiency = speedup / size;
  72.         printf("Speedup: %f\n", speedup);
  73.         printf("Efficiency: %f\n", efficiency);
  74.  
  75.         // Cleanup
  76.         free(A);
  77.         free(B);
  78.         free(C_seq);
  79.         free(C_par);
  80.     }
  81.  
  82.     free(localA);
  83.     free(localC);
  84.     MPI_Finalize();
  85.     return 0;
  86. }
  87.  
Success #stdin #stdout #stderr 0.27s 40556KB
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Standard input is empty
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Standard output is empty
stderr
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Error: unexpected symbol in "int main"
Execution halted
https://ideone.com/VaAUaf
language:
R (R 3.5.2)
created:
4 hours ago
visibility:
public

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