12 extern char** environ;
18 return (4.0 / (1.0 + a * a));
21 int main(
int argc,
char* argv[])
25 cout <<
"BooA" << endl;
27 int done = 0, n, myid, numprocs, i;
28 double PI25DT = 3.141592653589793238462643;
29 double mypi, pi, h, sum, x;
30 double startwtime = 0.0, endwtime;
32 char processor_name[MPI_MAX_PROCESSOR_NAME];
34 for (
int i = 0; i < argc; ++i)
35 cout <<
"argv[" << i <<
"] = " << argv[i]
38 MPI_Init(&argc, &argv);
39 MPI_Comm_size(MPI_COMM_WORLD, &numprocs);
40 MPI_Comm_rank(MPI_COMM_WORLD, &myid);
41 MPI_Get_processor_name(processor_name, &namelen);
43 fprintf(stderr,
"Process %d on %s\n",
44 myid, processor_name);
56 startwtime = MPI_Wtime();
58 MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
65 for (i = myid + 1; i <= n; i += numprocs)
67 x = h * ((double)i - 0.5);
72 MPI_Reduce(&mypi, &pi, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);
76 printf(
"pi is approximately %.16f, Error is %.16f\n",
77 pi, fabs(pi - PI25DT));
78 endwtime = MPI_Wtime();
79 printf(
"wall clock time = %f\n",
80 endwtime - startwtime);