static void wait(MPI_Request* req, MPI_Status * status);
static MPI_Request send_init(void *buf, int count, MPI_Datatype datatype, int dst, int tag, MPI_Comm comm);
static MPI_Request isend_init(void *buf, int count, MPI_Datatype datatype, int dst, int tag, MPI_Comm comm);
static void wait(MPI_Request* req, MPI_Status * status);
static MPI_Request send_init(void *buf, int count, MPI_Datatype datatype, int dst, int tag, MPI_Comm comm);
static MPI_Request isend_init(void *buf, int count, MPI_Datatype datatype, int dst, int tag, MPI_Comm comm);