|MPI_IREDUCE(sendbuf, recvbuf, count, datatype, op, root, comm, request)|
|IN sendbuf||address of send buffer (choice)|
|OUT recvbuf||address of receive buffer (choice, significant only at root)|
|IN count||number of elements in send buffer (non-negative integer)|
|IN datatype||data type of elements of send buffer (handle)|
|IN op||reduce operation (handle)|
|IN root||rank of root process (integer)|
|IN comm||communicator (handle)|
|OUT request||communication request (handle)|
int MPI_Ireduce(const void* sendbuf, void* recvbuf, int count, MPI_Datatype datatype, MPI_Op op, int root, MPI_Comm comm, MPI_Request *request)
MPI_Ireduce(sendbuf, recvbuf, count, datatype, op, root, comm, request, ierror)
TYPE(*), DIMENSION(..), INTENT(IN), ASYNCHRONOUS :: sendbuf
TYPE(*), DIMENSION(..), ASYNCHRONOUS :: recvbuf
INTEGER, INTENT(IN) :: count, root
TYPE(MPI_Datatype), INTENT(IN) :: datatype
TYPE(MPI_Op), INTENT(IN) :: op
TYPE(MPI_Comm), INTENT(IN) :: comm
TYPE(MPI_Request), INTENT(OUT) :: request
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
MPI_IREDUCE(SENDBUF, RECVBUF, COUNT, DATATYPE, OP, ROOT, COMM, REQUEST, IERROR)
<type> SENDBUF(*), RECVBUF(*)
INTEGER COUNT, DATATYPE, OP, ROOT, COMM, REQUEST, IERROR
This call starts a nonblocking variant of MPI_REDUCE (see Section Reduce ).
Advice to implementors.
The implementation is explicitly allowed to use different algorithms for
blocking and nonblocking reduction operations that might change the
order of evaluation of the operations. However, as for
MPI_REDUCE, it is strongly recommended that
MPI_IREDUCE be implemented so that the same result be
obtained whenever the function is applied on the same arguments,
appearing in the same order. Note that this may prevent optimizations
that take advantage of the physical location of processes.
( End of advice to implementors.)
Advice to users.
For operations which are not truly associative, the result delivered
upon completion of the nonblocking reduction may not exactly equal the
result delivered by the blocking reduction, even when specifying the
same arguments in the same order.
( End of advice to users.)