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MPI_Get_accumulate(3)		      MPI		 MPI_Get_accumulate(3)

NAME
       MPI_Get_accumulate  -  Perform an atomic, one-sided read-and-accumulate
       operation

SYNOPSIS
       int MPI_Get_accumulate(const void *origin_addr, int origin_count,
       MPI_Datatype origin_datatype, void *result_addr,
       int result_count, MPI_Datatype result_datatype,
       int target_rank,	MPI_Aint target_disp, int target_count,
       MPI_Datatype target_datatype, MPI_Op op,	MPI_Win	win)

       int MPI_Get_accumulate_c(const void *origin_addr, MPI_Count origin_count,
       MPI_Datatype origin_datatype, void *result_addr,
       MPI_Count result_count, MPI_Datatype result_datatype,
       int target_rank,	MPI_Aint target_disp,
       MPI_Count target_count, MPI_Datatype target_datatype,
       MPI_Op op, MPI_Win win)

INPUT PARAMETERS
       origin_addr
	      -	initial	address	of buffer (choice)
       origin_count
	      -	number of entries in origin buffer (non-negative integer)
       origin_datatype
	      -	datatype of each entry in origin buffer	(handle)
       result_count
	      -	number of entries in result buffer (non-negative integer)
       result_datatype
	      -	datatype of each entry in result buffer	(handle)
       target_rank
	      -	rank of	target (non-negative integer)
       target_disp
	      -	displacement from start	 of  window  to	 beginning  of	target
	      buffer (non-negative integer)
       target_count
	      -	number of entries in target buffer (non-negative integer)
       target_datatype
	      -	datatype of each entry in target buffer	(handle)
       op     -	reduce operation (handle)
       win    -	window object (handle)

OUTPUT PARAMETERS
       result_addr
	      -	initial	address	of result buffer (choice)

NOTES
       This  operations	 is  atomic  with respect to other "accumulate"	opera-
       tions.

       The get and accumulate steps are	executed atomically for	each basic el-
       ement in	the datatype (see MPI 3.0 Section 11.7 for details). The  pre-
       defined operation MPI_REPLACE provides fetch-and-set behavior.

       The  origin  and	 result	 buffers (origin_addr and result_addr) must be
       disjoint.  Each datatype	argument must be a predefined  datatype	 or  a
       derived	datatype where all basic components are	of the same predefined
       datatype. All datatype arguments	must be	constructed from the same pre-
       defined datatype. The operation op applies to elements of  that	prede-
       fined  type.  target_datatype must not specify overlapping entries, and
       the target buffer must fit in the target	window or in  attached	memory
       in a dynamic window.

       Any  of the predefined operations for MPI_Reduce	, as well as MPI_NO_OP
       or MPI_REPLACE can be specified as op. User-defined functions cannot be
       used. A new predefined operation, MPI_NO_OP ,  is  defined.  It	corre-
       sponds  to  the	associative  function  f (a, b)	= a; i.e., the current
       value in	the target memory is returned in the result buffer at the ori-
       gin and no operation is performed on the	target buffer.	MPI_NO_OP  can
       be   used  only	in  MPI_Get_accumulate	,  MPI_Rget_accumulate	,  and
       MPI_Fetch_and_op	.   MPI_NO_OP  cannot  be  used	 in  MPI_Accumulate  ,
       MPI_Raccumulate	,  or collective reduction operations, such as MPI_Re-
       duce and	others.

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_COUNT
	      -	Invalid	count argument.	 Count arguments must be non-negative;
	      a	count of zero is often valid.
       MPI_ERR_DISP
	      -
       MPI_ERR_RANK
	      -	Invalid	source or destination rank.   Ranks  must  be  between
	      zero  and	the size of the	communicator minus one;	ranks in a re-
	      ceive ( MPI_Recv , MPI_Irecv , MPI_Sendrecv , etc.) may also  be
	      MPI_ANY_SOURCE .

       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_WIN
	      -	Invalid	MPI window object
       MPI_ERR_OTHER
	      -	 Other	error;	use  MPI_Error_string  to get more information
	      about this error code.

SEE ALSO
       MPI_Rget_accumulate MPI_Fetch_and_op

				   2/3/2025		 MPI_Get_accumulate(3)

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