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MPI_Ireduce(3)                         MPI                        MPI_Ireduce(3)




NAME

       MPI_Ireduce -  Reduces values on all processes to a single value in a
       nonblocking way


SYNOPSIS

       int MPI_Ireduce(const void *sendbuf, void *recvbuf, int count,
       MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm,
       MPI_Request *request)

       int MPI_Ireduce_c(const void *sendbuf, void *recvbuf, MPI_Count count,
       MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm,
       MPI_Request *request)




INPUT PARAMETERS

       sendbuf
              - address of send buffer (choice)
       count  - number of elements in send buffer (non-negative integer)
       datatype
              - data type of elements of send buffer (handle)
       op     - reduce operation (handle)
       root   - rank of root process (integer)
       comm   - communicator (handle)



OUTPUT PARAMETERS

       recvbuf
              - address of receive buffer (choice)
       request
              - communication request (handle)



THREAD AND INTERRUPT SAFETY

       This routine is thread-safe.  This means that this routine may be safely
       used by multiple threads without the need for any user-provided thread
       locks.  However, the routine is not interrupt safe.  Typically, this is
       due to the use of memory allocation routines such as malloc or other non-
       MPICH runtime routines that are themselves not interrupt-safe.



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_ARG
              - Invalid argument.  Some argument is invalid and is not
              identified by a specific error class (e.g., MPI_ERR_RANK ).
       MPI_ERR_BUFFER
              - Invalid buffer pointer.  Usually a null buffer where one is not
              valid.
       MPI_ERR_COMM
              - Invalid communicator.  A common error is to use a null
              communicator in a call (not even allowed in MPI_Comm_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_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_OTHER
              - Other error; use MPI_Error_string to get more information about
              this error code.




                                    1/27/2023                     MPI_Ireduce(3)

mpi 4.1 - Generated Sun Jan 29 10:23:00 CST 2023
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