MPI.cpp

// ### Send and Receive
int MPI_Send(void *buf, int count, MPI_Datatype datatype, 
		int dest, int tag, MPI_Comm comm);
		
int MPI_Recv(void *buf, int count, MPI_Datatype datatype, 
		int source, int tag, MPI_Comm comm, MPI_Status *status);

// ### Size and Rank
int MPI_Comm_size(MPI_Comm comm, int *size);
int MPI_Comm_rank(MPI_Comm comm, int *rank);

	// usage:
	int myrank, nproc;
	MPI_Comm_size(MPI_COMM_WORLD, &nproc);
	MPI_Comm_rank(MPI_COMM_WORLD, &myrank);