#include
<stdlib.h>
#include
<stdio.h>
#include
<math.h>
#include
<mpi.h>
#define
USE_MPI
#define
SEED 35791246
main(int
argc, char
*argv[])
{
int
niter=0;
double
x,y;
int
i,j,count=0,mycount,mpi_error;
double
z;
double
pi;
int
myid,numprocs,proc,namelen;
MPI_Status status;
int
master =0;
int
tag = 123;
char
processor_name[MPI_MAX_PROCESSOR_NAME];
MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
MPI_Comm_rank(MPI_COMM_WORLD,&myid);
MPI_Get_processor_name(processor_name,&namelen);
if
(myid == 0) {
printf("How many iterations do you want each process to do?\n ");
fflush(stdout);
scanf("%d",&niter);
}
MPI_Bcast(&niter, 1, MPI_INT, 0, MPI_COMM_WORLD);
srand(SEED+123*myid);
mycount=0;
for
( i=0; i<niter; i++) {
x = (double
)rand()/RAND_MAX;
y = (double
)rand()/RAND_MAX;
z = x*x+y*y;
if
(z<=1) mycount++;
}
if
(myid ==0) {
count=mycount;
printf("Process %d running on processor %s sending hit count= %d to master process\n",myid,processor_name,mycount );
for
(proc=1; proc<numprocs; proc++) {
MPI_Recv(&mycount,1,MPI_REAL,proc,tag,MPI_COMM_WORLD,&status);
count +=mycount;
}
pi=(double
)count/(niter*numprocs)*4;
printf("\n # of trials= %d , estimate of pi is %.16f \n",niter*numprocs,pi);
} else
{
printf("Process %d running on processor %s sending hit count= %d to master process\n",myid,processor_name,mycount );
MPI_Send(&mycount,1,MPI_REAL,master,tag,MPI_COMM_WORLD);
}
mpi_error=MPI_Finalize();
if
(MPI_SUCCESS!=mpi_error)
return
mpi_error;
else
return
0;
}