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MPI_Isendrecv.3.rst

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MPI_Isendrecv

:ref:`MPI_Isendrecv` - Sends and receives a message.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Isendrecv(const void *sendbuf, int sendcount, MPI_Datatype sendtype,
    int dest, int sendtag, void *recvbuf, int recvcount,
    MPI_Datatype recvtype, int source, int recvtag,
    MPI_Comm comm, MPI_Request *request)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_ISENDRECV(SENDBUF, SENDCOUNT, SENDTYPE, DEST, SENDTAG,
        RECVBUF, RECVCOUNT, RECVTYPE, SOURCE, RECVTAG, COMM,
        REQUEST, IERROR)
    <type>    SENDBUF(*), RECVBUF(*)
    INTEGER    SENDCOUNT, SENDTYPE, DEST, SENDTAG
    INTEGER    RECVCOUNT, RECVTYPE, SOURCE, RECVTAG, COMM
    INTEGER    REQUEST, IERROR

Fortran 2008 Syntax

USE mpi_f08
MPI_Isendrecv(sendbuf, sendcount, sendtype, dest, sendtag, recvbuf,
        recvcount, recvtype, source, recvtag, comm, request, ierror)
    TYPE(*), DIMENSION(..), INTENT(IN) :: sendbuf
    TYPE(*), DIMENSION(..) :: recvbuf
    INTEGER, INTENT(IN) :: sendcount, dest, sendtag, recvcount, source,
    recvtag
    TYPE(MPI_Datatype), INTENT(IN) :: sendtype, recvtype
    TYPE(MPI_Comm), INTENT(IN) :: comm
    TYPE(MPI_Request) :: request
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

  • sendbuf: Initial address of send buffer (choice).
  • sendcount: Number of elements to send (integer).
  • sendtype: Type of elements in send buffer (handle).
  • dest: Rank of destination (integer).
  • sendtag: Send tag (integer).
  • recvcount: Maximum number of elements to receive (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).
  • 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. This 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.

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.

:ref:`MPI_Isendrecv` executes a non-blocking send and receive operation. Both send and receive use the same communicator, but possibly different tags. The send buffer and receive buffers must be disjoint, and may have different lengths and datatypes.

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

ERRORS

.. seealso::
   * :ref:`MPI_Isendrecv_replace`
   * :ref:`MPI_Sendrecv`
   * :ref:`MPI_Sendrecv_replace`