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)

INPUT PARAMETERS

       origin_addr
              - initial address of buffer (choice)
       datatype
              - datatype of the entry in origin, result, and target buffers (handle)
       target_rank
              - rank of target (non-negative integer)
       target_disp
              - displacement from start of window to beginning of target buffer (non-negative integer)
       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" 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 guarantee 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_DISP
              -
       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
       MPI_ERR_OTHER
              - Other error; use MPI_Error_string to get more information about this error code.

SEE ALSO

       MPI_Get_accumulate

                                                    2/9/2024                                 MPI_Fetch_and_op(3)