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#include <mpi.h>
#include <stdio.h>
int main(int argc, char *argv[])
{
int rank, nprocs, len, n, sum;
char pname[MPI_MAX_PROCESSOR_NAME];
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD,&nprocs);
MPI_Comm_rank(MPI_COMM_WORLD,&rank);
MPI_Get_processor_name(pname,&len);
printf("Hello world! from rank %d of %d on host %s\n", rank, nprocs,pname);
MPI_Barrier(MPI_COMM_WORLD);
if (rank==0) {
printf("Enter the number to broadcast ");
scanf("%d",&n);
}
MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
printf("1, rank %d, n= %d\n",rank,n);
if (rank==1) {
n=5;
MPI_Send(&n, 1, MPI_INT, 2, 0, MPI_COMM_WORLD);
printf("2. rank %d, n= %d\n",rank,n);
MPI_Recv(&n, 1, MPI_INT, 2, MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
printf("3. rank %d, n= %d\n",rank,n);
}
if (rank==2) {
MPI_Recv(&n, 1, MPI_INT,1, MPI_ANY_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
printf("2. rank %d, n= %d\n",rank,n);
n=15;
MPI_Send(&n, 1, MPI_INT,1, 0, MPI_COMM_WORLD);
printf("3. rank %d, n= %d\n",rank,n);
}
MPI_Barrier(MPI_COMM_WORLD);
sum=0;
MPI_Reduce(&n,&sum,1,MPI_INT,MPI_SUM,0,MPI_COMM_WORLD);
printf("4. rank %d, n= %d\n",rank,sum);
MPI_Finalize();
return 0;
}