NAME

       MPI_Issend - Starts a nonblocking synchronous send.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Issend(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_ISSEND(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_Issend(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::Issend(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

       Starts a synchronous 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.

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_Ssend