MPIAccumulate(3OpenMPI) MPIAccumulate(3OpenMPI)

NAME
       MMPPIIAAccccuummuullaattee   - Combines the contents of the origin buffer with that
       of a target buffer.


SSYYNNTTAAXX
CC SSyynnttaaxx
       #include 
       int MPIAccumulate(void *originaddr, int origincount,
            MPIDatatype origindatatype, int targetrank,
            MPIAint targetdisp, int targetcount,
            MPIDatatype targetdatatype, MPIOp op, MPIWin win)


FFoorrttrraann SSyynnttaaxx ((sseeee FFOORRTTRRAANN 7777 NNOOTTEESS))
       INCLUDE 'mpif.h'
       MPIACCUMULATE(ORIGINADDR, ORIGINCOUNT, ORIGINDATATYPE, TARGETRANK,
            TARGETDISP, TARGETCOUNT, TARGETDATATYPE, OP, WIN, IERROR)
             ORIGINADDR(*)
            INTEGER(KIND=MPIADDRESSKIND) TARGETDISP
            INTEGER ORIGINCOUNT, ORIGINDATATYPE, TARGETRANK, TARGETCOUNT,
            TARGETDATATYPE, OP, WIN, IERROR


CC++++ SSyynnttaaxx
       #include 
       void MPI::Win::Accumulate(const void* originaddr, int origincount,
            const MPI::Datatype& origindatatype, int targetrank,
            MPI::Aint targetdisp, int targetcount, const MPI::Datatype&
            targetdatatype, const MPI::Op& op) const


IINNPPUUTT PPAARRAAMMEETTEERRSS
       originaddr
                 Initial address of buffer (choice).

       origincount
                 Number of entries in buffer (nonnegative integer).

       origindatatype
                 Data type of each buffer entry (handle).

       targetrank
                 Rank of target (nonnegative integer).

       targetdisp
                 Displacement from start of  window  to  beginning  of  target
                 buffer (nonnegative integer).

       targetcount
                 Number of entries in target buffer (nonnegative integer).

       targetdatatype
                 Data type of each entry in target buffer (handle).

       op        Reduce operation (handle).

       win       Window object (handle).


OOUUTTPPUUTT PPAARRAAMMEETTEERR
       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       MPIAccumulate  is a function used for one-sided MPI communication that
       adds the contents of the origin buffer (as defined by originaddr, ori-
       gincount,  and  origindatatype)  to the buffer specified by the argu-
       ments targetcount and targetdatatype, at offset targetdisp,  in  the
       target window specified by targetrank and win, using the operation op.
       The target window can only be accessed by  processes  within  the  same
       node. This is similar to MPIPut, except that data is combined into the
       target area instead of overwriting it.

       Any of the predefined operations for  MPIReduce  can  be  used.  User-
       defined  functions  cannot be used. For example, if op is MPISUM, each
       element of the origin buffer is added to the corresponding  element  in
       the target, replacing the former value in the target.

       Each datatype argument must be a predefined data type or a derived data
       type, where all basic components are of the same predefined data  type.
       Both  datatype  arguments  must be constructed from the same predefined
       data type. The operation op applies  to  elements  of  that  predefined
       type.   The  targetdatatype  argument  must  not  specify  overlapping
       entries, and the target buffer must fit in the target window.

       A new predefined operation, MPIREPLACE, is defined. It corresponds  to
       the  associative function f(a, b) =b; that is, the current value in the
       target memory is replaced by the value supplied by the origin.



FFOORRTTRRAANN 7777 NNOOTTEESS
       The MPI standard prescribes portable Fortran syntax for the TARGETDISP
       argument  only for Fortran 90.  FORTRAN 77 users may use the non-porta-
       ble syntax

            INTEGER*MPIADDRESSKIND TARGETDISP

       where MPIADDRESSKIND is a constant defined in mpif.h  and  gives  the
       length of the declared integer in bytes.


NNOOTTEESS
       MPIPut  is  a  special  case  of  MPIAccumulate,  with  the operation
       MPIREPLACE. Note, however, that MPIPut and MPIAccumulate  have  dif-
       ferent constraints on concurrent updates.

       It is the user's responsibility to guarantee that, when using the accu-
       mulate  functions,  the  target  displacement  argument  is  such  that
       accesses  to the window are properly aligned according to the data type
       arguments in the call to the MPIAccumulate function.


EERRRROORRSS
       Almost all MPI routines return an error value; C routines as the  value
       of  the  function  and Fortran routines in the last argument. C++ func-
       tions do not return errors. If the default  error  handler  is  set  to
       MPI::ERRORSTHROWEXCEPTIONS, then on error the C++ exception mechanism
       will be used to throw an MPI:Exception object.

       Before the error value is returned, the current MPI  error  handler  is
       called.  By  default, this error handler aborts the MPI job, except for
       I/O  function  errors.  The  error  handler   may   be   changed   with
       MPICommseterrhandler; the predefined error handler MPIERRORSRETURN
       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.


SEE ALSO
       MPIPut
       MPIReduce



Open MPI 1.2                    September 2006        MPIAccumulate(3OpenMPI)