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  1. #include <mpi.h>
  2. #include <iostream>
  3. using namespace std;
  4.  
  5. #include <vector>
  6. #include <cstdlib>
  7.  
  8. using namespace std;
  9.  
  10. // Function to multiply matrices
  11. void matrixMultiply(const vector<vector<int>>& A, const vector<vector<int>>& B, vector<vector<int>>& C, int startRow, int endRow, int N, int P) {
  12.     for (int i = startRow; i < endRow; i++) {
  13.         for (int j = 0; j < P; j++) {
  14.             C[i][j] = 0;
  15.             for (int k = 0; k < N; k++) {
  16.                 C[i][j] += A[i][k] * B[k][j];
  17.             }
  18.         }
  19.     }
  20. }
  21.  
  22. int main(int argc, char* argv[]) {
  23.     MPI_Init(&argc, &argv);
  24.  
  25.     int rank, size;
  26.     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  27.     MPI_Comm_size(MPI_COMM_WORLD, &size);
  28.  
  29.     int M = 4, N = 4, P = 4; // Dimensions of matrices
  30.  
  31.     vector<vector<int>> A(M, vector<int>(N, 0));
  32.     vector<vector<int>> B(N, vector<int>(P, 0));
  33.     vector<vector<int>> C(M, vector<int>(P, 0));
  34.  
  35.     // Master initializes matrices
  36.     if (rank == 0) {
  37.         for (int i = 0; i < M; i++) {
  38.             for (int j = 0; j < N; j++) {
  39.                 A[i][j] = rand() % 10; // Random values between 0 and 9
  40.             }
  41.         }
  42.         for (int i = 0; i < N; i++) {
  43.             for (int j = 0; j < P; j++) {
  44.                 B[i][j] = rand() % 10;
  45.             }
  46.         }
  47.  
  48.         cout << "Matrix A:\n";
  49.         for (const auto& row : A) {
  50.             for (int val : row) cout << val << " ";
  51.             cout << "\n";
  52.         }
  53.  
  54.         cout << "\nMatrix B:\n";
  55.         for (const auto& row : B) {
  56.             for (int val : row) cout << val << " ";
  57.             cout << "\n";
  58.         }
  59.         cout << "\n";
  60.     }
  61.  
  62.     // Broadcast matrix B to all processes
  63.     for (int i = 0; i < N; i++) {
  64.         MPI_Bcast(B[i].data(), P, MPI_INT, 0, MPI_COMM_WORLD);
  65.     }
  66.  
  67.     int rows_per_proc = M / size;
  68.     vector<vector<int>> local_A(rows_per_proc, vector<int>(N));
  69.     vector<vector<int>> local_C(rows_per_proc, vector<int>(P, 0));
  70.  
  71.     for (int i = 0; i < rows_per_proc; i++) {
  72.         MPI_Scatter(A[i].data(), N, MPI_INT, local_A[i].data(), N, MPI_INT, 0, MPI_COMM_WORLD);
  73.     }
  74.  
  75.     int startRow = rank * rows_per_proc;
  76.     int endRow = startRow + rows_per_proc;
  77.     matrixMultiply(A, B, C, startRow, endRow, N, P);
  78.  
  79.     for (int i = 0; i < rows_per_proc; i++) {
  80.         MPI_Gather(local_C[i].data(), P, MPI_INT, C[startRow].data(), P, MPI_INT, 0, MPI_COMM_WORLD);
  81.     }
  82.  
  83.     if (rank == 0) {
  84.         cout << "Result Matrix C:\n";
  85.         for (const auto& row : C) {
  86.             for (int val : row) cout << val << " ";
  87.             cout << "\n";
  88.         }
  89.     }
  90.  
  91.     MPI_Finalize();
  92.     return 0;
  93. }
  94.  
Success #stdin #stdout #stderr 0.32s 40732KB
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Standard input is empty
stdout
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Standard output is empty
stderr
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Error: unexpected symbol in "using namespace"
Execution halted
https://ideone.com/eTzqyk
language:
R (R 3.5.2)
created:
2 days ago
visibility:
public

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