[MOAB-dev] Fwd: question about reduce_tags behavior

[Tim Tautges]

On 05/04/2012 11:27 AM, Lorenzo Alessio Botti wrote:
> I don't know if it's a bug or if I initially misunderstood the behavior of reduce_tags
>
> Know it works as follows
>
> pcomm->reduce_tags(gid_tag_vec, gid_tag_vec, MPI_SUM, sharedFaces);
> provides in gid_tag_vec the sum of the tag values on shared faces, so it sums the value of the tag on the owned and on
> the not_owned entity. This is what I need in my code.
>
> pcomm->reduce_tags(gid_tag_vec, gid_sum_tag_vec, MPI_OP_NULL, sharedFaces);
> provides in gid_sum_tag_vec the values of gid_tag_vec on the owned ents, so this call replicates the behavior of
> exchange_tags
>
> pcomm->reduce_tags(gid_tag_vec, gid_sum_tag_vec, MPI_SUM, sharedFaces);
> provides in gid_sum_tag_vec the sum of the gid_tag on the owned entity and the gid_sum_tag on the actual process
> (independently of the pstatus)
>

This should be fixed now, in R5514.  In an unusual burst of discipline, I also added a test case for it (made debugging 
easier, besides just being A Good Idea).  Lemme know if it doesn't appear fixed for you, and thanks for the bug report.

- tim

> Is this the expected behavior?
>
> Thanks
> Lorenzo
>
>>
>> On May 4, 2012, at 5:46 PM, Tautges wrote:
>>
>>> If I read your message right, it's a bug with when you want the result in a different tag? Will fix this soon, should
>>> be easy.
>>>
>>> On your msg about mbzoltan, the fix is much appreciated, we'll definitely get that in the code base. Dont know yet
>>> about the option string, haven't looked at code yet.
>>>
>>> - tim
>>>
>>> (Sent from an Androd that dosnt autocorect as wel as an ipone)
>>>
>>>
>>>
>>> -------- Original message --------
>>> Subject: Re: question about reduce_tags behavior
>>> From: Lorenzo Alessio Botti <ihabiamx at yahoo.it <mailto:ihabiamx at yahoo.it>>
>>> To: Tim Tautges <tautges at mcs.anl.gov <mailto:tautges at mcs.anl.gov>>,MOAB-dev at mcs.anl.gov <mailto:MOAB-dev at mcs.anl.gov>
>>> CC:
>>>
>>>
>>> Hi Tim,
>>> I've found the bug in my code...
>>> To get the sum of a tag on shared entities I need to call
>>>
>>> pcomm->reduce_tags(gid_tag_vec, gid_tag_vec, MPI_SUM, sharedFaces);
>>> and not
>>> pcomm->reduce_tags(gid_tag_vec, gid_sum_tag_vec, MPI_SUM, sharedFaces);
>>>
>>> Here is the new version, now it works...
>>>
>>
>

-- 
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              Tim Tautges            Argonne National Laboratory
          (tautges at mcs.anl.gov)      (telecommuting from UW-Madison)
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