NAME

       MPI_Irecv - Starts a standard-mode, nonblocking receive.

SYNTAX

C Syntax

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

Fortran Syntax

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

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Irecv(buf, count, datatype, source, tag, comm, request, ierror)
            TYPE(*), DIMENSION(..), ASYNCHRONOUS :: buf
            INTEGER, INTENT(IN) :: count, source, 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::Irecv(void* buf, int count, const Datatype&
            datatype, int source, int tag) const

INPUT PARAMETERS

       buf       Initial address of receive buffer (choice).

       count     Number of elements in receive buffer (integer).

       datatype  Datatype of each receive buffer element (handle).

       source    Rank of source (integer).

       tag       Message tag (integer).

       comm      Communicator (handle).

OUTPUT PARAMETERS

       request   Communication request (handle).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       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 receive call indicates that the system may start writing data into the receive buffer.  The
       receiver  should  not  access  any  part  of  the receive buffer after a nonblocking receive operation is
       called, until the receive completes.

       A receive 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_Recv MPI_Probe MPI_Test MPI_Testany MPI_Wait MPI_Waitany

4.1.6                                             Sep 30, 2023                                      MPI_Irecv(3)