[Mpi-comments] Error in MPI_Neighbor_alltoallw example?
Timothy Brown
Timothy.Brown-1 at Colorado.EDU
Fri Dec 5 10:33:13 CST 2014
Ah, perfect thanks! I didn't know about the trac/ticket system.
Tim
> On Dec 5, 2014, at 9:04 AM, Rajeev Thakur <thakur at mcs.anl.gov> wrote:
>
> Yes, see https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/420
>
> Rajeev
>
>
> On Dec 5, 2014, at 9:41 AM, Timothy Brown <Timothy.Brown-1 at Colorado.EDU> wrote:
>
>> Hello.
>>
>> I was trying to use MPI_Neighbor_alltoallw() and was following the example on page 333 of the MPI-3.0 standard. However I believe the send and receive counts are incorrect. Lines 21 to 25:
>>
>> DO i=1,num_neigh
>> sndcounts(i) = 100
>> rcvcounts(i) = 100
>> rcvtypes(i) = sndtypes(i)
>> END DO
>>
>> Since the send/receive counts for 1 and 2 are vectors types of length 100, we should be sending/receiving only 1 type/element. As follows:
>>
>> sndcounts(1) = 1
>> sndcounts(2) = 1
>> sndcounts(3) = 100
>> sndcounts(4) = 100
>>
>> rcvcounts = sndcounts
>>
>> Indeed if I compile the example as per the standard, I get data corruption.
>>
>> I couldn't find this in the errata published on May 14, 2014. However if it is a known mistake please ignore my comment.
>>
>> Regards
>> Timothy Brown
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