[Mpi-22] MPI-2.1 ambiguity?

[William Gropp]

One piece of relevant text in MPI 2.0 is in section 4.12.6 (in  
MPI-2.0) says that "All predefined datatypes can be used in datatype  
constructors in any language."  However, the example uses  
MPI_Type_f2c ton convert the Fortran handle to the C version before  
passing it into the MPI_Type_create_struct routine, so this text  
could be interpreted as allowing the use of those datatypes through  
the handle conversion mechanism without requiring them to be defined  
in each languages header file.  Presumably the requirement is that  
they be predefined with the value that you'd get from the handle  
conversion function?

Bill

On Jul 16, 2008, at 8:18 AM, Hubert Ritzdorf wrote:

> Hi,
>
> when I remember correctly, it was decided to provide the C MPI  
> datatypes
> in Fortran since
> the Fortran datatypes are supported in C and C++.
>
> Hubert
>
> Jeff Squyres wrote:
>> I will file a proposal about this if there is a problem, but I wanted
>> to ask the group before I did so.  In the changelog for MPI-2.1:
>>
>> 2. Section 3.2.2 on page 27, Section 16.1.6 on page 453, and Annex  
>> A.1
>> on page 491.
>> MPI_LONG_LONG_INT, MPI_LONG_LONG (as synonym),  
>> MPI_UNSIGNED_LONG_LONG,
>> MPI_SIGNED_CHAR, and MPI_WCHAR are moved from optional to official  
>> and they
>> are therefore defined for all three language bindings.
>>
>> Note that it says that these C datatype names must be in all three
>> language bindings.
>>
>> Are C MPI datatypes supposed to be available in Fortran?  I looked in
>> mpif.h for Open MPI, MPICH2, HP MPI, and Intel MPI, and I didn't  
>> see C
>> MPI datatypes in there (e.g., MPI_INT and MPI_FLOAT).
>>
>> So:
>>
>> - is there language somewhere in MPI that says that C datatypes are
>> not supposed to be in mpif.h? (and therefore the MPI-2.1 changelog is
>> wrong)
>>
>> or
>>
>> - are all 4 of the above MPI's wrong for not including the C  
>> datatypes
>> in mpif.h?
>>
>> --Jeff Squyres
>> Cisco Systems
>>
>>
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William Gropp
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign



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