MPI_IRECV, MPI_Irecv

Purpose

Performs a nonblocking receive operation.

C synopsis

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

C++ synopsis

#include mpi.h
MPI::Request MPI::Comm::Irecv(void *buf, int count, const MPI::Datatype& datatype,
                              int source, int tag) const;

FORTRAN synopsis

include 'mpif.h' or use mpi
MPI_IRECV(CHOICE BUF,INTEGER COUNT,INTEGER DATATYPE,INTEGER SOURCE,
          INTEGER TAG,INTEGER COMM,INTEGER REQUEST,INTEGER IERROR)

Description

This subroutine starts a nonblocking receive and returns a handle to a
request object. You can later use the request to query the status of the
communication or wait for it to complete.

A nonblocking receive call means the system may start writing data into the
receive buffer. Once the nonblocking receive operation is called, do not
access any part of the receive buffer until the receive is complete.

Parameters

buf
     is the initial address of the receive buffer (choice) (OUT)
count
     is the number of elements in the receive buffer (integer) (IN)
datatype
     is the datatype of each receive buffer element (handle) (IN)
source
     is the rank of source or MPI_ANY_SOURCE (integer) (IN)
tag
     is the message tag or MPI_ANY_TAG (positive integer) (IN)
comm
     is the communicator (handle) (IN)
request
     is the communication request (handle) (OUT)
IERROR
     is the FORTRAN return code. It is always the last argument.

Notes

The message received must be less than or equal to the length of the
receive buffer. If all incoming messages do not fit without truncation, an
overflow error occurs. If a message arrives that is shorter than the
receive buffer, then only those locations corresponding to the actual
message are changed. If an overflow occurs, it is flagged at the MPI_WAIT
or MPI_TEST. See MPI_RECV for more information.

Errors

Invalid count
     count < 0

Invalid datatype

Type not committed

Invalid source
     source < 0 or source > = groupsize

Invalid tag
     tag < 0

Invalid comm

MPI not initialized

MPI already finalized

Related information

     MPI_RECV
     MPI_RECV_INIT
     MPI_WAIT