NAME

       MPI_Recv -  Blocking receive for a message

SYNOPSIS

       int MPI_Recv(void *buf, int count, MPI_Datatype datatype, int source, int tag,
                    MPI_Comm comm, MPI_Status *status)

OUTPUT PARAMETERS

       buf    - initial address of receive buffer (choice)
       status - status object (Status)

INPUT PARAMETERS

       count  - maximum 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)

NOTES

       The  count  argument  indicates  the maximum length of a message; the actual length of the
       message can be determined with MPI_Get_count .

THREAD AND INTERRUPT SAFETY

       This routine is thread-safe.  This means that this routine may be safely used by  multiple
       threads  without the need for any user-provided thread locks.  However, the routine is not
       interrupt safe.  Typically, this is due to the use of memory allocation routines  such  as
       malloc or other non-MPICH runtime routines that are themselves not interrupt-safe.

NOTES FOR FORTRAN

       All  MPI  routines  in  Fortran  (except  for MPI_WTIME and MPI_WTICK ) have an additional
       argument ierr at the end of the argument list.  ierr  is  an  integer  and  has  the  same
       meaning  as  the  return  value  of  the  routine  in  C.   In  Fortran,  MPI routines are
       subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

       The status argument must be declared as an array of size MPI_STATUS_SIZE , as  in  integer
       status(MPI_STATUS_SIZE) .

ERRORS

       All  MPI  routines  (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as
       the value of the function and Fortran routines in the last argument.  Before the value  is
       returned,  the current MPI error handler is called.  By default, this error handler aborts
       the MPI  job.   The  error  handler  may  be  changed  with  MPI_Comm_set_errhandler  (for
       communicators),  MPI_File_set_errhandler  (for files), and MPI_Win_set_errhandler (for RMA
       windows).  The MPI-1 routine MPI_Errhandler_set may be used but  its  use  is  deprecated.
       The  predefined  error  handler  MPI_ERRORS_RETURN may be used to cause error values to be
       returned.  Note that MPI does not guarentee that an  MPI  program  can  continue  past  an
       error; however, MPI implementations will attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_COMM
              -  Invalid  communicator.   A  common error is to use a null communicator in a call
              (not even allowed in MPI_Comm_rank ).
       MPI_ERR_TYPE
              - Invalid datatype argument.  Additionally, this error can occur if an  uncommitted
              MPI_Datatype (see MPI_Type_commit ) is used in a communication call.
       MPI_ERR_COUNT
              - Invalid count argument.  Count arguments must be non-negative; a count of zero is
              often valid.
       MPI_ERR_TAG
              - Invalid tag argument.  Tags must be non-negative; tags in a receive ( MPI_Recv  ,
              MPI_Irecv  ,  MPI_Sendrecv , etc.) may also be MPI_ANY_TAG .  The largest tag value
              is available through the the attribute MPI_TAG_UB .

       MPI_ERR_RANK
              - Invalid source or destination rank.  Ranks must be between zero and the  size  of
              the  communicator  minus  one;  ranks  in  a  receive  (  MPI_Recv  ,  MPI_Irecv  ,
              MPI_Sendrecv , etc.) may also be MPI_ANY_SOURCE .

                                            11/12/2016                                MPI_Recv(3)