MPI_Reduce - Reduces values on all processes to a single
       value


SYNOPSIS

       C:

            #include <mpi.h>

            int MPI_Reduce ( sendbuf, recvbuf, count, datatype,
            op, root, comm )
            void             *sendbuf;
            void             *recvbuf;
            int               count;
            MPI_Datatype      datatype;
            MPI_Op            op;
            int               root;
            MPI_Comm          comm;

       C++:

            #include <mpi.h>

            void Intracomm::Reduce(
            const void*       sendbuf,
            void*             recvbuf,
            int               count,
            const Datatype&   datatype,
            const Op&         op,
            int               root) const

       Fortran:

            INCLUDE "mpif.h" (or USE MPI)

            <type> SENDBUF(*), RECVBUF(*)
            INTEGER count, datatype, op, root, comm, ierror

            CALL MPI_REDUCE(sendbuf, recvbuf, count, datatype, op, root, comm, ierror)


STANDARDS

       This release implements the MPI 1.2 standard, as
       documented by the MPI Forum in the spring 1997 release of
       MPI:  A Message Passing Interface Standard.


DESCRIPTION

       The MPI_Reduce routine reduces values on all processes to
       a single value.  This routine accepts the following
       parameters:

       sendbuf   Specifies the address of the send buffer


       count     Specifies the number of elements in the send
                 buffer (integer)

       datatype  Specifies the data type of elements of the send
                 buffer (handle)

       op        Specifies the reduce operation (handle)

       root      Specifies the rank of the root process (integer)

       comm      Specifies the communicator (handle)

       recvbuf   Returns the address of the receive buffer
                 (choice, significant only at root)

       ierror    Specifies the return code value for successful
                 completion, which is in MPI_SUCCESS.
                 MPI_SUCCESS is defined in the mpif.h file.


NOTES

       This implementation currently uses a simple tree
       algorithm.


Man(1) output converted with man2html