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  1. #include <iostream>
  2. #include <cmath>
  3. #include <mpi.h>
  4. #include <fstream>
  5. #include <vector>
  6. #include <cstdlib> // for system function
  7.  
  8. using namespace std;
  9.  
  10. void writeDataToFile(const string& filename, int x, long double y) {
  11.     ofstream file(filename, ios::app);
  12.     if (file.is_open()) {
  13.         printf("size and time: %f",y);
  14.         file << x << " " << y<<" \n" << endl;
  15.         file.close();
  16.     }
  17.     else {
  18.         cerr << "Unable to open file for writing." <<endl;
  19.     }
  20. }
  21.  
  22. double f(double x) {
  23.     // Функция, которую мы интегрируем
  24.     return cos(2*x+3)*sin(3*x) + 3;
  25. }
  26.  
  27. double simpson(double a, double b, int n, double h) {
  28.     double sum = f(a) + f(b);
  29.  
  30.     for (int i = 1; i < n; i += 2) {
  31.         double x = a + i * h;
  32.         sum += 4 * f(x);
  33.     }
  34.  
  35.     for (int i = 2; i < n - 1; i += 2) {
  36.         double x = a + i * h;
  37.         sum += 2 * f(x);
  38.     }
  39.  
  40.     return sum * h / 3.0;
  41. }
  42.  
  43.  
  44. int main(int argc, char** argv) {
  45.  
  46.     const double a = 0.0;
  47.     const double b = 1;
  48.     const int n = 240000; 
  49.  
  50.     int rank, size=4;
  51.     long double min_start = 4800000, max_end = 0, start, end, local_result, total_result;
  52.  
  53.     MPI_Init(&argc, &argv);
  54.     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  55.     MPI_Comm_size(MPI_COMM_WORLD, &size);
  56.     MPI_Barrier(MPI_COMM_WORLD);
  57.  
  58.     start = MPI_Wtime();
  59.  
  60.     cout << "Process " << rank << " of " << size << " is running." << endl;
  61.  
  62.  
  63.     // Вычисляем локальный результат для каждого процесса
  64.     int local_n = n / size;
  65.     double local_a = a + rank * (b - a) / size;
  66.     double local_b = local_a + (b - a) / size;
  67.     double h = (b - a) / n;
  68.  
  69.     local_result = simpson(local_a, local_b, local_n, h);
  70.  
  71.  
  72.     MPI_Reduce(&local_result, &total_result, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
  73.     MPI_Barrier(MPI_COMM_WORLD);
  74.     end = MPI_Wtime();
  75.  
  76.  
  77.     if (rank == 0) {
  78.         cout << "Total result: " << total_result << endl;
  79.     }
  80.  
  81.     int numproc;
  82.  
  83.     numproc = size;
  84.  
  85.  
  86.  
  87.     // Find max time
  88.     if (min_start > start) {
  89.         min_start = start;
  90.     }
  91.  
  92.     if (max_end < end) {
  93.         max_end = end;
  94.     }
  95.  
  96.     if (rank == 0) {
  97.         printf("Time taken to process: %f", (max_end - min_start));
  98.     }
  99.     if (rank == 0) {
  100.         writeDataToFile("data.txt", numproc, (max_end - min_start));
  101.     }
  102.     MPI_Finalize();
  103.  
  104.  
  105.  
  106.  
  107.     return 0;
  108. }
  109.  
  110.  
Success #stdin #stdout #stderr 0.27s 40768KB
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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/HDfXvT
language:
R (R 3.5.2)
created:
14 days ago
visibility:
public

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