#include <mpi.h>
#include <iostream.h>
#include <math.h>

int main( int argc, char *argv[])
{
   int n = 1000000000;
   int i;

   double pi;
   double h;
   double x;

   int PARnp;
   int PARid;
   char PARname[MPI_MAX_PROCESSOR_NAME];
   int PARlen;
   int PARrc;
   if (PARrc= MPI_Init(&argc, &argv)) 
   {
	  cerr<<"Error starting MPI program. Terminating."<<endl;
	  MPI_Abort(MPI_COMM_WORLD, PARrc);
   }
   MPI_Comm_size(MPI_COMM_WORLD, &PARnp);
   MPI_Comm_rank(MPI_COMM_WORLD, &PARid);
   MPI_Get_processor_name(PARname,&PARlen);
   cout<<"Process "<<PARid<<" on "<<PARname<<endl;

   h = 1.0 / (double) n;
   pi= 0.0;

   for(i=PARid+1; i<n+1;i+=PARnp)
   {
	  x = h * ((double)i - 0.5);
	  pi +=(4.0 / (1.0 + x*x));
   }
   pi = h * pi;

   double PARpi;
   MPI_Reduce(&pi,&PARpi,1,MPI_DOUBLE,MPI_SUM,0,MPI_COMM_WORLD);
   pi=PARpi;

   if (PARid == 0) {
	  cout<<"pi = "<<pi<<endl;
   }

   MPI_Finalize();

   return 0;
}