#include "mpi.h" 
#include <stdio.h> 
#define SIZE 4 
int main(argc,argv) 
int argc; char *argv[]; 
{ 
int numtasks, rank, source=0, dest, tag=1, i; 
float a[SIZE][SIZE] = {1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0}; 
float b[SIZE]; 

MPI_Status stat; 
MPI_Datatype rowtype; 

MPI_Init(&argc,&argv); 
MPI_Comm_rank(MPI_COMM_WORLD, &rank); 
MPI_Comm_size(MPI_COMM_WORLD, &numtasks); 

MPI_Type_contiguous(SIZE, MPI_FLOAT, &rowtype); 
MPI_Type_commit(&rowtype); 

if (numtasks == SIZE) 
   { if (rank == 0) {
           for (i=0; i<numtasks; i++) 
MPI_Send(&a[i][0], 1, rowtype, i, tag, MPI_COMM_WORLD); } 

MPI_Recv(b, SIZE, MPI_FLOAT, source, tag, MPI_COMM_WORLD, &stat);

 printf("rank= %d b= %3.1f %3.1f %3.1f %3.1f\n", rank,b[0],b[1],b[2],b[3]); } 
else printf("Must specify %d processors. Terminating.\n",SIZE); 
MPI_Finalize(); 
}