Newsgroups: comp.parallel.mpi
From: Sanjay Velamparambil <velampar@uiuc.edu>
Subject: Re: New Ranks after MPI_Comm_dup
Organization: University  of Illinois at Urbana-Champaign
Date: Mon, 01 Dec 1997 21:50:08 -0600
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Message-ID: <34838570.4A944C75@uiuc.edu>

>

Hi,

   Thank you very much for the answers to my question.  Later on I figured
out,
following almost the same reasoning as that of Raja, that the ranks must be
preserved.

 Incidentally, calling the MPI_Comm_rank would not have solved my problem,
since I just
wanted a different context for my communications, with the ranks preserved.
I would have had to
use MPI_Group_translate_ranks,  to work with the same data structure I have.

Regards,
Sanjay

> Andre Fachat <fachat@physik.tu-chemnitz.de> wrote:
> >Which, nevertheless, does not mean that all implementations do.
> >To avoid problems, call MPI_Comm_rank() with the new communicator.
>
> Andre,
> MPI_Comm_dup() mandates that the old and new communicators have the
> "same" group(s).  This is independent of the "advice to implementors"
> paragraph.