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#include <mpi.h>
int main(int argc, char *argv[])
{
int myrank, nprocs;
int n, i;
double h, s, pi;
MPI_Comm master;
MPI_Init(&argc, &argv);
MPI_Comm_get_parent(&master);
MPI_Comm_size(master, &nprocs);
MPI_Comm_rank(master, &myrank);
MPI_Bcast(&n, 1, MPI_INT, 0, master);
h = 1.0 / (double) n;
s = 0.0;
for (i = myrank+1; i < n+1; i += nprocs) {
double x = h * (i - 0.5);
s += 4.0 / (1.0 + x*x);
}
pi = s * h;
MPI_Reduce(&pi, MPI_BOTTOM, 1, MPI_DOUBLE,
MPI_SUM, 0, master);
MPI_Comm_disconnect(&master);
MPI_Finalize();
return 0;
}
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