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MPI_Isendrecv_replace.3.rst

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MPI_Isendrecv_replace

MPI_Isendrecv_replace - Sends and receives a message using a single buffer.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Isendrecv_replace(void *buf, int count, MPI_Datatype datatype,
    int dest, int sendtag, int source, int recvtag, MPI_Comm comm,
    MPI_Request *request)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_ISENDRECV_REPLACE(BUF, COUNT, DATATYPE, DEST, SENDTAG, SOURCE,
        RECVTAG, COMM, REQUEST, IERROR)
    <type>    BUF(*)
    INTEGER    COUNT, DATATYPE, DEST, SENDTAG
    INTEGER    SOURCE, RECVTAG, COMM
    INTEGER    REQUEST, IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_Isendrecv_replace(buf, count, datatype, dest, sendtag, source, recvtag,
        comm, request, ierror)
    TYPE(*), DIMENSION(..) :: buf
    INTEGER, INTENT(IN) :: count, dest, sendtag, source, recvtag
    TYPE(MPI_Datatype), INTENT(IN) :: datatype
    TYPE(MPI_Comm), INTENT(IN) :: comm
    TYPE(MPI_Request) :: request
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT/OUTPUT PARAMETER

  • buf: Initial address of send and receive buffer (choice).

INPUT PARAMETERS

  • count: Number of elements in send and receive buffer (integer).
  • datatype: Type of elements to send and receive (handle).
  • dest: Rank of destination (integer).
  • sendtag: Send message tag (integer).
  • source: Rank of source (integer).
  • recvtag: Receive message tag (integer).
  • comm: Communicator (handle).

OUTPUT PARAMETERS

  • request: Communication request (handle).
  • ierror: Fortran only: Error status (integer).

DESCRIPTION

The non-blocking send-receive operations combine in one call the sending of a message to one destination and the receiving of another message, from another process. The two (source and destination) are possibly the same. A send-receive operation is useful for executing a shift operation across a chain of processes. The send-receive operation can be used in conjunction with the functions described in the "Process Topologies" chapter of the MPI Standard in order to perform shifts on various logical topologies. Also, a send-receive operation is useful for implementing remote procedure calls.

A message sent by a send-receive operation can be received by a regular receive operation or probed by a probe operation; a send-receive operation can receive a message sent by a regular send operation.

MPI_Isendrecv_replace executes a non-blocking send and receive. The same buffer is used both for the send and for the receive, so that the message sent is replaced by the message received.

A non-blocking send-receive request can be determined to be completed by calling the MPI_Wait, MPI_Waitany, MPI_Test, or MPI_Testany with the request returned by this function.

ERRORS

* MPI_Isendrecv * MPI_Sendrecv * MPI_Sendrecv_replace