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MPI_Neighbor_alltoallw(3) MPI MPI_Neighbor_alltoallw(3)
MPI_Neighbor_alltoallw - Like MPI_Neighbor_alltoallv but it allows one
to send and receive with different types to and from each neighbor.
int MPI_Neighbor_alltoallw(const void *sendbuf, const int sendcounts, const MPI_Aint sdispls, const MPI_Datatype sendtypes, void *recvbuf, const int recvcounts, const MPI_Aint rdispls, const MPI_Datatype recvtypes, MPI_Comm comm)
- starting address of the send buffer (choice)
- non-negative integer array (of length outdegree) specifying
the number of elements to send to each neighbor
- integer array (of length outdegree). Entry j specifies the
displacement in bytes (relative to sendbuf) from which to take
the outgoing data destined for neighbor j (array of integers)
- array of datatypes (of length outdegree). Entry j specifies
the type of data to send to neighbor j (array of handles)
- non-negative integer array (of length indegree) specifying the
number of elements that are received from each neighbor
- integer array (of length indegree). Entry i specifies the
displacement in bytes (relative to recvbuf) at which to place
the incoming data from neighbor i (array of integers).
- array of datatypes (of length indegree). Entry i specifies
the type of data received from neighbor i (array of handles).
comm - communicator with topology structure (handle)
- starting address of the receive buffer (choice)
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-
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
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.