NAME

       MPI_Irsend - Starts a ready-mode nonblocking send.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Irsend(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_IRSEND(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_Irsend(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::Irsend(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_Irsend   starts   a   ready-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 to
       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.

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_Rsend