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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <time.h> // For srand() and rand()
  4. #include <mpi.h>
  5.  
  6. #define N 100 // Maximum size of the matrix
  7. #define MAX_RANDOM 100 // Maximum random number
  8.  
  9. void fill_with_random(double A[N][N], double b[N], int n, int my_rank, int p, MPI_Comm comm) {
  10.     int i, j;
  11.  
  12.     // Seed the random number generator with the current time
  13.     srand(time(NULL));
  14.  
  15.     // Fill A with random numbers
  16.     for (i = 0; i < n; i++) {
  17.         for (j = 0; j < n; j++) {
  18.             A[i][j] = rand() % MAX_RANDOM + 1; // Random number between 1 and MAX_RANDOM
  19.         }
  20.     }
  21.  
  22.     // Fill b with random numbers
  23.     for (i = 0; i < n; i++) {
  24.         b[i] = rand() % MAX_RANDOM + 1; // Random number between 1 and MAX_RANDOM
  25.     }
  26. }
  27.  
  28. void forward_elimination(double A[N][N], double b[N], int n, int k, int my_rank, int p, MPI_Comm comm) {
  29.     int i, j, l, pivot_row;
  30.     double pivot, tmp;
  31.  
  32.     for (int col = 0; col < n; col++) {
  33.         // Find the pivot row for column col among the rows assigned to this processor
  34.         pivot = 0.0;
  35.         for (i = col % k; i < n; i += k) {
  36.             if (A[i][col] > pivot) {
  37.                 pivot = A[i][col];
  38.                 pivot_row = i;
  39.             }
  40.         }
  41.         // Broadcast the pivot row to all processors
  42.         MPI_Bcast(&pivot_row, 1, MPI_INT, col % k, comm);
  43.         // Swap rows
  44.         if (my_rank == col % k) {
  45.             if (pivot_row != col) {
  46.                 for (j = 0; j < n; j++) {
  47.                     tmp = A[col][j];
  48.                     A[col][j] = A[pivot_row][j];
  49.                     A[pivot_row][j] = tmp;
  50.                 }
  51.                 tmp = b[col];
  52.                 b[col] = b[pivot_row];
  53.                 b[pivot_row] = tmp;
  54.             }
  55.         }
  56.         // Eliminate elements below the pivot
  57.         for (i = (col % k == my_rank) ? (col + 1) : ((col + 1) % k); i < n; i += k) {
  58.             tmp = A[i][col] / A[col][col];
  59.             for (j = col; j < n; j++) {
  60.                 A[i][j] -= tmp * A[col][j];
  61.             }
  62.             b[i] -= tmp * b[col];
  63.         }
  64.     }
  65. }
  66.  
  67. void backward_substitution(double A[N][N], double b[N], double x[N], int n, int k, int my_rank, int p, MPI_Comm comm) {
  68.     int i, j;
  69.     double sum;
  70.  
  71.     for (int col = n - 1; col >= 0; col--) {
  72.         sum = 0.0;
  73.         for (i = (col % k == my_rank) ? col : ((col + 1) % k); i < n; i += k) {
  74.             sum += A[col][i] * x[i];
  75.         }
  76.         MPI_Bcast(&sum, 1, MPI_DOUBLE, col % k, comm);
  77.         if (col % k == my_rank) {
  78.             x[col] = (b[col] - sum) / A[col][col];
  79.         }
  80.     }
  81. }
  82.  
  83. int main(int argc, char **argv) {
  84.     int my_rank, p, n, k;
  85.     double A[N][N], b[N], x[N];
  86.     MPI_Comm comm;
  87.  
  88.     MPI_Init(&argc, &argv);
  89.     MPI_Comm_rank(MPI_COMM_WORLD, &my_rank);
  90.     MPI_Comm_size(MPI_COMM_WORLD, &p);
  91.  
  92.     if (my_rank == 0) {
  93.         printf("Enter the size of the matrix (n): ");
  94.         scanf("%d", &n);
  95.         printf("Enter the value of k: ");
  96.         scanf("%d", &k);
  97.  
  98.         // Fill A and b with random numbers
  99.         fill_with_random(A, b, n, my_rank, p, MPI_COMM_WORLD);
  100.     }
  101.  
  102.     // Broadcast n and k to all processors
  103.     MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
  104.     MPI_Bcast(&k, 1, MPI_INT, 0, MPI_COMM_WORLD);
  105.  
  106.     // Scatter A and b among processors
  107.     MPI_Bcast(A, N * N, MPI_DOUBLE, 0, MPI_COMM_WORLD);
  108.     MPI_Bcast(b, N, MPI_DOUBLE, 0, MPI_COMM_WORLD);
  109.  
  110.     // Perform forward elimination
  111.     forward_elimination(A, b, n, k, my_rank, p, MPI_COMM_WORLD);
  112.  
  113.     // Perform backward substitution
  114.     backward_substitution(A, b, x, n, k, my_rank, p, MPI_COMM_WORLD);
  115.  
  116.     // Gather the solution x to the root processor
  117.     MPI_Gather(x, n, MPI_DOUBLE, x, n, MPI_DOUBLE, 0, MPI_COMM_WORLD);
  118.  
  119.     // Print the solution
  120.     if (my_rank == 0) {
  121.         printf("Solution:\n");
  122.         for (int i = 0; i < n; i++) {
  123.             printf("%lf ", x[i]);
  124.         }
  125.         printf("\n");
  126.     }
  127.  
  128.     MPI_Finalize();
  129.     return 0;
  130. }
  131.  
Success #stdin #stdout #stderr 0.3s 40476KB
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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 "void fill_with_random"
Execution halted
https://ideone.com/ar3v0Y
language:
R (R 3.5.2)
created:
9 days ago
visibility:
public

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