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MPIX_Neighbor_alltoall(3)	      MPI	     MPIX_Neighbor_alltoall(3)

NAME
       MPIX_Neighbor_alltoall  -   In  this  function, each process i receives
       data items from each process j if an edge (j,i) exists in the  topology
       graph  or  Cartesian  topology.	 Similarly,  each process i sends data
       items to	all processes j	where an edge (i,j) exists. This call is  more
       general than MPI_NEIGHBOR_ALLGATHER in that different data items	can be
       sent to each neighbor. The k-th block in	send buffer is sent to the  k-
       th  neighboring process and the l-th block in the receive buffer	is re-
       ceived from the l-th neighbor.

SYNOPSIS
       int MPIX_Neighbor_alltoall(const	void *sendbuf, int sendcount, MPI_Datatype sendtype, void *recvbuf, int	recvcount, MPI_Datatype	recvtype, MPI_Comm comm)

INPUT PARAMETERS
       sendbuf
	      -	starting address of the	send buffer (choice)
       sendcount
	      -	number of elements sent	to each	neighbor  (non-negative	 inte-
	      ger)
       sendtype
	      -	data type of send buffer elements (handle)
       recvcount
	      -	 number	 of elements received from each	neighbor (non-negative
	      integer)
       recvtype
	      -	data type of receive buffer elements (handle)
       comm   -	communicator (handle)

OUTPUT PARAMETERS
       recvbuf
	      -	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-
       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 guarentee that an MPI program can continue past
       an error; however, MPI implementations will attempt to  continue	 when-
       ever possible.

LOCATION
       src/mpi/topo/nhb_alltoall.c

				   9/20/2012	     MPIX_Neighbor_alltoall(3)

NAME | SYNOPSIS | INPUT PARAMETERS | OUTPUT PARAMETERS | THREAD AND INTERRUPT SAFETY | NOTES FOR FORTRAN | ERRORS | LOCATION

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