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  1. //Carter Wright
  2. //Program to compute the value of Pi
  3. //demonstrating parallel computing capabilities
  4.  
  5.  
  6. // Include necessary libraries
  7. #include <mpi.h>
  8. #include <cmath>
  9. #include <cstdlib>
  10. #include <iostream>
  11.  
  12. // Function to compute pi using the sum of the reciprocals of the squares method
  13. double compute_pi_reciprocal_squares(int rank, int size, int num_terms) {
  14.     double sum = 0.0;
  15.     // Each process computes a part of the sum
  16.     for (int i = rank + 1; i <= num_terms; i += size) {
  17.         sum += 1.0 / (i * i);
  18.     }
  19.     return sum;
  20. }
  21.  
  22. // Function to compute pi using the trapezoid rule
  23. double compute_pi_trapezoid(int rank, int size, int num_intervals) {
  24.     double h = 1.0 / num_intervals;
  25.     double sum = 0.0;
  26.     // Each process computes a part of the sum
  27.     for (int i = rank + 1; i <= num_intervals; i += size) {
  28.         double x = h * (i - 0.5);
  29.         sum += 4.0 / (1.0 + x * x);
  30.     }
  31.     return h * sum;
  32. }
  33.  
  34. int main(int argc, char *argv[]) {
  35.     // Initialize MPI and get the rank and size
  36.     int rank, size;
  37.     MPI_Init(&argc, &argv);
  38.     MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  39.     MPI_Comm_size(MPI_COMM_WORLD, &size);
  40.  
  41.     // Process 0 asks the user for the method and the number of terms or intervals
  42.     if (rank == 0) {
  43.         std::cout << "Enter the method you wish to use (1=reciprocal squares, 2=trapezoid rule): ";
  44.         int method;
  45.         std::cin >> method;
  46.         // Broadcast the method to all processes
  47.         MPI_Bcast(&method, 1, MPI_INT, 0, MPI_COMM_WORLD);
  48.  
  49.         std::cout << "Enter the number of terms or intervals: ";
  50.         int num;
  51.         std::cin >> num;
  52.         // Broadcast the number of terms or intervals to all processes
  53.         MPI_Bcast(&num, 1, MPI_INT, 0, MPI_COMM_WORLD);
  54.     }
  55.  
  56.     // All processes receive the method and the number of terms or intervals
  57.     int method, num;
  58.     MPI_Bcast(&method, 1, MPI_INT, 0, MPI_COMM_WORLD);
  59.     MPI_Bcast(&num, 1, MPI_INT, 0, MPI_COMM_WORLD);
  60.  
  61.     // Depending on the method, compute the local sum
  62.     double local_sum;
  63.     if (method == 1) {
  64.         local_sum = compute_pi_reciprocal_squares(rank, size, num);
  65.     } else if (method == 2) {
  66.         local_sum = compute_pi_trapezoid(rank, size, num);
  67.     }
  68.  
  69.     // Reduce the local sums to a global sum
  70.     double global_sum;
  71.     MPI_Reduce(&local_sum, &global_sum, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
  72.  
  73.     // Process 0 computes and prints the value of Pi
  74.     if (rank == 0) {
  75.         double pi;
  76.         if (method == 1) {
  77.             pi = sqrt(6.0 * global_sum);
  78.         } else if (method == 2) {
  79.             pi = global_sum;
  80.         }
  81.         printf("Computed value of Pi: %f\n", pi);
  82.     }
  83.  
  84.     // Finalize MPI and end the program
  85.     MPI_Finalize();
  86.     return 0;
  87. }
  88.  
  89.  
Success #stdin #stdout #stderr 0.25s 40816KB
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Standard input is empty
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Standard output is empty
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Error: unexpected '/' in "/"
Execution halted
https://ideone.com/JbCDU3
language:
R (R 3.5.2)
created:
10 days ago
visibility:
public

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