From gilles at rist.or.jp  Sun Mar  1 23:08:34 2020
From: gilles at rist.or.jp (Gilles Gouaillardet)
Date: Mon, 2 Mar 2020 14:08:34 +0900
Subject: [Mpi-comments] User-Defined Reduction Operations: possible
 enhancement
Message-ID: <738b0290-edbc-ad8a-948c-cce602f16645@rist.or.jp>

Dear MPI Forum,


In chapter 5.9.5 (User-Defined Reduction Operations), page 185 of MPI 
3.1 and page 187 of MPI 2019 Draft,

it reads :

Advice to implementors. We outline below a naive and inefficient 
implementation of
MPI_REDUCE not supporting the "in place" option.


Strictly speaking, the outlined implementation is only valid for 
intra-communicators (and does not support the "in place" option),

so you might consider amending this line before MPI 2019 is out.


Best regards,


Gilles