From: treumann@XXXXXXXXXX
Importance: Normal
Subject: Re: Another clarification
To: William Gropp <gropp@XXXXXXXXXXX>
Cc: mpi-core@XXXXXXXXXXX
Date: Wed, 10 May 2000 09:59:12 -0400
X-MIMETrack: Serialize by Router on D01ML075/01/M/IBM(Release 5.0.2b (Intl)|18 January
 2000) at 10/05/2000 10:10:33
MIME-Version: 1.0
Content-type: text/plain; charset=us-ascii


Bill -

You raise the issue of a zero byte datatype being used to query
MPI_Get_count or MPI_Get_elements on a status.  Both calls are allowed to
return MPI_UNDEFINED yet you suggest the answer zero be mandated.   We
detect the divide by 0 attempt and return MPI_UNDEFINED.  This seems like
the right result to me.

Can you explain why you prefer zero?  I am interested if it is because zero
is better for some real user situation or because you consider zero  more
consistent with the MPI standard (or both).

Dick Treumann                IBM RS/6000 SP Development
Tele (914) 433-7846         Fax (914) 433-8363