Sends and receives a message


#include "mpi.h"
int MPI_Sendrecv( sendbuf, sendcount, sendtype, dest, sendtag, 
                  recvbuf, recvcount, recvtype, source, recvtag, 
                  comm, status )
void         *sendbuf;
int           sendcount;
MPI_Datatype  sendtype;
int           dest, sendtag;
void         *recvbuf;
int           recvcount;
MPI_Datatype  recvtype;
int           source, recvtag;
MPI_Comm      comm;
MPI_Status   *status;

Input Parameters

sendbuf - initial address of send buffer (choice)
sendcount - number of elements in send buffer (integer)
sendtype - type of elements in send buffer (handle)
dest - rank of destination (integer)
sendtag - send tag (integer)
recvcount - number of elements in receive buffer (integer)
recvtype - type of elements in receive buffer (handle)
source - rank of source (integer)
recvtag - receive tag (integer)
comm - communicator (handle)

Output Parameters

recvbuf - initial address of receive buffer (choice)
status - status object (Status). This refers to the receive operation.

Notes for Fortran

All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have an additional argument ierr at the end of the argument list. ierr is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the call statement.

All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGER in Fortran.


All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Errhandler_set; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarentee that an MPI program can continue past an error.

MPI_SUCCESS - No error; MPI routine completed successfully.
MPI_ERR_COMM - Invalid communicator. A common error is to use a null communicator in a call (not even allowed in MPI_Comm_rank).
MPI_ERR_COUNT - Invalid count argument. Count arguments must be non-negative; a count of zero is often valid.
MPI_ERR_TYPE - Invalid datatype argument. May be an uncommitted
MPI_Datatype (see MPI_Type_commit).
MPI_ERR_TAG - Invalid tag argument. Tags must be non-negative; tags in a receive (MPI_Recv, MPI_Irecv, MPI_Sendrecv, etc.) may also be MPI_ANY_TAG. The largest tag value is available through the the attribute MPI_TAG_UB.
MPI_ERR_RANK - Invalid source or destination rank. Ranks must be between zero and the size of the communicator minus one; ranks in a receive (MPI_Recv, MPI_Irecv, MPI_Sendrecv, etc.) may also be MPI_ANY_SOURCE.