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


       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)

       Accumulate   origin_count   elements  of  type  origin_datatype  from  the  origin  buffer
       (origin_addr) to the buffer at offset target_disp,  in  the  target  window  specified  by
       target_rank  and  win,  using the operation op and return in the result buffer result_addr
       the content of the target buffer before the accumulation.


              - initial address of buffer (choice)
              - number of entries in buffer (nonnegative integer)
              - datatype of each buffer entry (handle)
              - initial address of result buffer (choice)
              - number of entries in result buffer (non-negative integer)
              - datatype of each entry in result buffer (handle)
              - rank of target (nonnegative integer)
              - displacement from start of window to  beginning  of  target  buffer  (nonnegative
              - number of entries in target buffer (nonnegative integer)
              - datatype of each entry in target buffer (handle)
       op     - predefined reduce operation (handle)
       win    - window object (handle)


       This operations is atomic with respect to other "accumulate" operations.

       The  get  and  accumulate  steps  are  executed  atomically  for each basic element in the
       datatype (see MPI 3.0 Section 11.7 for  details).  The  predefined  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 predefined datatype. The operation op applies to elements of that predefined
       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 corresponds 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 origin 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_Reduce and others.


       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.


       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.

              - No error; MPI routine completed successfully.
              - Invalid argument.  Some argument is invalid and is not identified by  a  specific
              error class (e.g., MPI_ERR_RANK ).
              - Invalid count argument.  Count arguments must be non-negative; a count of zero is
              often valid.
              - Invalid source or destination rank.  Ranks must be between zero and the  size  of
              the  communicator  minus  one;  ranks  in  a  receive  (  MPI_Recv  ,  MPI_Irecv  ,
              MPI_Sendrecv , etc.) may also be MPI_ANY_SOURCE .

              - Invalid datatype argument.  Additionally, this error can occur if an  uncommitted
              MPI_Datatype (see MPI_Type_commit ) is used in a communication call.
              - Invalid MPI window object


       MPI_Rget_accumulate MPI_Fetch_and_op

                                            11/9/2015                       MPI_Get_accumulate(3)