Re: [Boost-users] mpi all_reduce

Subject: Re: [Boost-users] mpi all_reduce
From: Riccardo Murri (riccardo.murri_at_[hidden])
Date: 2010-12-02 17:37:34

Hi Phillip,

On Thu, Dec 2, 2010 at 7:08 PM, Kraus Philipp
<philipp.kraus_at_[hidden]> wrote:
> how can I use the mpi::all_reduce with std::accumulate? I would reduce the
> values of each process with a sum function
>

You can use mpi::all_reduce like this::

    int local_value = ...; // local computation
    int global_value = 0;
    mpi::all_reduce(comm_, local_value, global_value, std::plus<int>());
    // now `global_value` holds the sum of `local_value` of all MPI ranks

where `comm_` is an instance of mpi::communicator; other binary
operations are available besides std::plus (or you can define your
own).

Best regards,
Riccardo