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while (!done) 
  { 
    if (myid == 0) { 
        printf("Enter the number of intervals: (0 quits) "); 
        scanf("%d",&n); 
    } 
    MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD); 
    if (n == 0) break; 
  
 
h   = 1.0 / (double) n; 
    sum = 0.0; 
    for (i = myid + 1; i <= n; i += numprocs) { 
        x = h * ((double)i - 0.5); 
        sum += 4.0 / (1.0 + x*x); 
    } 
    mypi = h * sum; 
    
 
MPI_Reduce(&mypi, &pi, 1, MPI_DOUBLE, MPI_SUM, 0, 
                MPI_COMM_WORLD); 
    
 
if (myid == 0) 
        printf("pi is approximately %.16f, Error is %.16f\n", 
               pi, fabs(pi - PI25DT)); 
  } 
  MPI_Finalize(); 
} 

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