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  1. #include <mpi.h>
  2. #include <math.h> // Add this line
  3. #include <stdlib.h>
  4. #include <stdio.h>
  5.  
  6. int main(int argc, char *argv[]) {
  7.     int myid, numprocs, i;
  8.     unsigned long n;
  9.     long double PI = 3.14159265358979323846264338327950288419716939937510;
  10.     long double pi, sum, partial_sum, x;
  11.  
  12.     MPI_Init(&argc, &argv);
  13.     MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
  14.     MPI_Comm_rank(MPI_COMM_WORLD, &myid);
  15.  
  16.     if (myid == 0) {
  17.         if (argc != 2) {
  18.             printf("Usage: %s <num_terms>\n", argv[0]);
  19.             MPI_Abort(MPI_COMM_WORLD, 1);
  20.         }
  21.         n = strtoul(argv[1], NULL, 10);
  22.     }
  23.  
  24.     MPI_Bcast(&n, 1, MPI_UNSIGNED_LONG, 0, MPI_COMM_WORLD);
  25.  
  26.     partial_sum = 0.0;
  27.     for(i = n / numprocs * myid + 1; i <= n / numprocs * (myid + 1); i++) {
  28.         x = ((long double)i - 0.5) / n;
  29.         partial_sum += 4.0 / (1.0 + x * x);
  30.     }
  31.  
  32.     MPI_Reduce(&partial_sum, &sum, 1, MPI_LONG_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
  33.  
  34.     if (myid == 0) {
  35.         pi = sum / n;
  36.         printf("pi is approximately %.22Lf, Error is %.22Lf\n", pi, fabsl(pi - PI));
  37.     }
  38.  
  39.     MPI_Finalize();
  40.     return 0;
  41. }
  42.  
Success #stdin #stdout #stderr 0.27s 40688KB
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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 "int main"
Execution halted
https://ideone.com/O6LjSJ
language:
R (R 3.5.2)
created:
10 days ago
visibility:
public

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