[MPI3 Fortran] MPI Data types

Jeff Squyres jsquyres at cisco.com
Thu May 7 10:41:37 CDT 2009

On May 7, 2009, at 11:33 AM, N.M. Maclaren wrote:

> >That would be suitable for a Fortran value-add/add-on library.  It is
> >not suitable for the Fortran MPI bindings, unfortunately -- we need  
> to
> >preserve pretty much a 1:1 mapping of Fortran functions to C  
> functions
> >for the official bindings.
> That means you have to stick to non-standard Fortran 77.  Sorry, but  
> the
> memory models of C and Fortran just don't overlap on any superset.

I don't understand the implications of what you are saying.  Be gentle  
with me; I'm *NOT* a Fortran expert (or anywhere close).

> >Craig has talked about making a value-add Fortran library that would
> >do stuff like this (similar to how the Boost.MPI library did this  
> for C
> >++).
> I thought that we were discussing features to enable MPI-3 to  
> support things
> like Fortran array arguments that have no equivalent in C (principally
> assumed shape).

I don't understand.  What does it matter if there is no equivalent  
data type in C?

MPI is about message passing -- as long as we can get a memory layout  
description of the data to send / receive, then it doesn't matter what  
language the data will be accessed from.

Jeff Squyres
Cisco Systems

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