/* reduce.c
 * Example of MPI_Reduce
 *
 */

#include <stdio.h>
#include "mpi.h"
int main(int argc, char *argv[])
{
     int rank,size,t,x=0,root=0;
     MPI_Init(&argc,&argv);
     MPI_Comm_rank(MPI_COMM_WORLD,&rank);
     MPI_Comm_size(MPI_COMM_WORLD,&size);
     t=rank+1;
     printf("(before) rank=%d, t=%d, x=%d\n",rank,t,x);
     MPI_Reduce(&t,&x,1,MPI_INT,MPI_SUM,root,MPI_COMM_WORLD);
     printf("(after ) rank=%d, t=%d, x=%d\n",rank,t,x);
     MPI_Finalize();
     return 0;
}