#include "mpi.h" 
#include <stdio.h> 
 int main(argc,argv) 
int argc; char *argv[]; 
{
 int i,numtasks, rank, count, source; 
       float sendbuf ; 
       float recvbuf;
              MPI_Init(&argc,&argv);
              MPI_Comm_rank(MPI_COMM_WORLD, &rank); 
              MPI_Comm_size(MPI_COMM_WORLD,&numtasks);
              count = 1; 
              sendbuf=(float)rank;
              MPI_Allreduce(&sendbuf,&recvbuf,count, 
                              MPI_FLOAT,MPI_SUM,MPI_COMM_WORLD); 
                     printf("rank= %d SUM:%f\n ",rank,recvbuf);
       MPI_Finalize(); 
}