NAME

       MPI_Isend - Starts a standard-mode, nonblocking send.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Isend(const void *buf, int count, MPI_Datatype datatype, int dest,
            int tag, MPI_Comm comm, MPI_Request *request)

Fortran Syntax

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

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Isend(buf, count, datatype, dest, tag, comm, request, ierror)
            TYPE(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: buf
            INTEGER, INTENT(IN) :: count, dest, tag
            TYPE(MPI_Datatype), INTENT(IN) :: datatype
            TYPE(MPI_Comm), INTENT(IN) :: comm
            TYPE(MPI_Request), INTENT(OUT) :: request
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       #include <mpi.h>
       Request Comm::Isend(const void* buf, int count, const
            Datatype& datatype, int dest, int tag) const

INPUT PARAMETERS

       buf       Initial address of send buffer (choice).

       count     Number of elements in send buffer (integer).

       datatype  Datatype of each send buffer element (handle).

       dest      Rank of destination (integer).

       tag       Message tag (integer).

       comm      Communicator (handle).

OUTPUT PARAMETERS

       request   Communication request (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_Isend  starts  a  standard-mode, nonblocking send. Nonblocking calls allocate a communication request
       object and associate it with the request handle (the argument request). The request can be used later  to
       query the status of the communication or wait for its completion.

       A  nonblocking  send  call  indicates  that the system may start copying data out of the send buffer. The
       sender should not modify any part of the send buffer after a nonblocking send operation is called,  until
       the send completes.

       A  send  request  can  be  determined  being completed by calling the MPI_Wait, MPI_Waitany, MPI_Test, or
       MPI_Testany with request returned by this function.

ERRORS

       Almost all MPI routines return an error value; C routines as  the  value  of  the  function  and  Fortran
       routines in the last argument. C++ functions do not return errors. If the default error handler is set to
       MPI::ERRORS_THROW_EXCEPTIONS,  then  on  error  the  C++  exception  mechanism  will  be used to throw an
       MPI::Exception object.

       Before the error value is returned, the current MPI error handler  is  called.  By  default,  this  error
       handler  aborts  the  MPI  job,  except  for  I/O  function errors. The error handler may be changed with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values
       to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

SEE ALSO

       MPI_Send MPI_Wait MPI_Waitany MPI_Test MPI_Testany

4.1.6                                             Sep 30, 2023                                      MPI_Isend(3)