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MPI_Neighbor_alltoallw(3)	      MPI	     MPI_Neighbor_alltoallw(3)

NAME
       MPI_Neighbor_alltoallw -	 Like MPI_Neighbor_alltoallv but it allows one
       to send and receive with	different types	to and from each neighbor.

SYNOPSIS
       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)

       int MPI_Neighbor_alltoallw_c(const void *sendbuf, const MPI_Count sendcounts[],
       const MPI_Aint sdispls[],
       const MPI_Datatype sendtypes[], void *recvbuf,
       const MPI_Count recvcounts[],
       const MPI_Aint rdispls[],
       const MPI_Datatype recvtypes[], MPI_Comm	comm)

INPUT PARAMETERS
       sendbuf
	      -	starting address of send buffer	(choice)
       sendcounts
	      -	 non-negative  integer	array (of length outdegree) specifying
	      the number of elements to	send to	 each  neighbor	 (non-negative
	      integer)
       sdispls
	      -	 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	(integer)
       sendtypes
	      -	 array	of  datatypes (of length outdegree). Entry j specifies
	      the type of data to send to neighbor j (handle)
       recvcounts
	      -	non-negative integer array (of length indegree)	specifying the
	      number of	elements that are received from	 each  neighbor	 (non-
	      negative integer)
       rdispls
	      -	integer	array (of length indegree). Entry i specifies the dis-
	      placement	 in  bytes (relative to	recvbuf) at which to place the
	      incoming data from neighbor i (integer)
       recvtypes
	      -	array of datatypes (of length indegree). Entry i specifies the
	      type of data received from neighbor i (handle)
       comm   -	communicator with topology structure (handle)

OUTPUT PARAMETERS
       recvbuf
	      -	starting address of 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-
       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.

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 com-
       municators), MPI_File_set_errhandler (for files),  and  MPI_Win_set_er-
       rhandler	 (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 guarantee	that an	MPI program can	continue  past
       an  error;  however, MPI	implementations	will attempt to	continue when-
       ever possible.

       MPI_SUCCESS
	      -	No error; MPI routine completed	successfully.
       MPI_ERR_BUFFER
	      -	Invalid	buffer pointer.	 Usually a null	buffer	where  one  is
	      not valid.
       MPI_ERR_COMM
	      -	 Invalid communicator.	A common error is to use a null	commu-
	      nicator in a call	(not even allowed in MPI_Comm_rank ).
       MPI_ERR_COUNT
	      -	Invalid	count argument.	 Count arguments must be non-negative;
	      a	count of zero is often valid.
       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_OTHER
	      -	Other error; use  MPI_Error_string  to	get  more  information
	      about this error code.

				   2/3/2025	     MPI_Neighbor_alltoallw(3)

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