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MPI_Fetch_and_op(3)                   MPI                  MPI_Fetch_and_op(3)

NAME
       MPI_Fetch_and_op -  Perform one-sided read-modify-write.

SYNOPSIS
       int MPI_Fetch_and_op(const void *origin_addr, void *result_addr,
               MPI_Datatype datatype, int target_rank, MPI_Aint target_disp,
               MPI_Op op, MPI_Win win)

       Accumulate one element of type 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.

INPUT PARAMETERS
       origin_addr
              - initial address of buffer (choice)
       result_addr
              - initial address of result buffer (choice)
       datatype
              - datatype of the entry in origin, result, and target buffers
              (handle)
       target_rank
              - rank of target (nonnegative integer)
       target_disp
              - displacement from start of window to beginning of target
              buffer (non-negative integer)
       op     - reduce operation (handle)
       win    - window object (handle)

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

       The generic functionality of MPI_Get_accumulate might limit the
       performance of fetch-and-increment or fetch-and-add calls that might be
       supported by special hardware operations.  MPI_Fetch_and_op thus allows
       for a fast implementation of a commonly used subset of the
       functionality of MPI_Get_accumulate .

       The origin and result buffers (origin_addr and result_addr) must be
       disjoint.  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. The datatype argument must be a predefined
       datatype.

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
       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.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_ARG
              - Invalid argument.  Some argument is invalid and is not
              identified by a specific error class (e.g., MPI_ERR_RANK ).
       MPI_ERR_COUNT
              - Invalid count argument.  Count arguments must be non-negative;
              a count of zero is often valid.
       MPI_ERR_OP
              - Invalid operation.  MPI operations (objects of type MPI_Op )
              must either be one of the predefined operations (e.g., MPI_SUM )
              or created with MPI_Op_create .

       MPI_ERR_RANK
              - 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 .

       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

SEE ALSO
       MPI_Get_accumulate

                                   11/9/2015               MPI_Fetch_and_op(3)