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  1. #include <stdio.h>
  2. #include <mpi.h>
  3.  
  4. double f(double x) {
  5.     return x * x;
  6. }
  7.  
  8. double trapezoidal_rule(double a, double b, int n, double h) {
  9.     double integral = (f(a) + f(b)) / 2.0;
  10.     for (int i = 1; i < n; i++) {
  11.         double x = a + i * h;
  12.         integral += f(x);
  13.     }
  14.     integral *= h;
  15.     return integral;
  16. }
  17.  
  18. int main(int argc, char** argv) {
  19.     int rank, size, n = 1024;
  20.     double a = 0.0, b = 5.0, h, local_a, local_b;
  21.     int local_n;
  22.     double local_integral, total_integral;
  23.  
  24.     MPI_Init(&argc, &argv);
  25.     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  26.     MPI_Comm_size(MPI_COMM_WORLD, &size);
  27.  
  28.     h = (b - a) / n;
  29.     local_n = n / size;
  30.     local_a = a + rank * local_n * h;
  31.     local_b = local_a + local_n * h;
  32.  
  33.     // Each process computes its part of the integral
  34.     local_integral = trapezoidal_rule(local_a, local_b, local_n, h);
  35.  
  36.     // Combine all results into total_integral using MPI_Reduce
  37.     MPI_Reduce(&local_integral, &total_integral, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
  38.  
  39.     // Print the result from rank 0
  40.     if (rank == 0) {
  41.         printf("The integral of f(x) = x^2 over [0, 5] is: %.6f\n", total_integral);
  42.     }
  43.  
  44.     MPI_Finalize();
  45.     return 0;
  46. }
  47.  
Success #stdin #stdout #stderr 0.27s 40848KB
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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 "double f"
Execution halted
https://ideone.com/URTJxH
language:
R (R 3.5.2)
created:
1 day ago
visibility:
public

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