parrelle computing

#include "mpi.h" #include <stdio.h> #include <math.h> double f(a) double a; { return (4.0 / (1.0 + a*a)); } int main(int argc,char *argv[]) { int i, n, myrank, nproc, done = 0; double PI25DT = 3.141592653589793238462643; double mypi, pi, h, sum, x; MPI_Init(&argc,&argv); MPI_Comm_size(MPI_COMM_WORLD,&nproc); MPI_Comm_rank(MPI_COMM_WORLD,&myrank); n = 0; while (!done) { if (myrank == 0) { printf("Enter the number of intervals: (0 quits)\n"); scanf("%d",&n); } MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD); // printf("I am process %d and value n is %d\n", myid, n); if (n == 0) done = 1; else { h = 1.0 / (double) n; sum = 0.0; for (i = myrank + 1; i <= n; i += nproc) { x = h * ((double)i - 0.5); sum += f(x); } mypi = h * sum; MPI_Reduce(&mypi, &pi, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD); if (myrank == 0) printf("\npi is approximately %.16f, Error is %.16f\n\n", pi, fabs(pi - PI25DT)); } } MPI_Finalize(); return 0; }