[Trilinos-Users] AztecOO: AZ_extract_comm_info

[Heroux, Michael A]

Andrea,

AztecOO has a very specific ordering of global Ids required for the column
map.  It is good that you are allowing Epetra to construct the column map,
but it is very likely that you have a row without any entries.  This is
often the cause of this kind of problem.  AztecOO expects each row on a
processor to have at least one nonzero entry on that processor.

Let me know if you have this issue or not.

Mike

On 12/20/12 12:12 PM, "Raymond Tuminaro" <rstumin at sandia.gov> wrote:

>Andrea,
>   I suspect that this obscure error message is something that I wrote
>about 10+ years ago before Trilinos really even
>existed. I'm not sure why you are getting this, but I can perhaps tell
>you what it means. For Aztec (which obviously
>sits inside Trilinos) all the ghost elements of a vector (that is
>elements of a vector needed -but not owned- by a
>processor to perform its local part of a matrix-vector product) must have
>a local numbering which is greater than
>all the vector elements that are owned by the processor. For example, if
>a processor owns 10 elements, then the way
>local ids are numbered for both matrices and vectors should be so that
>v[0:9] correspond to the locally owned vector
>components while v[> 9] would be the ghost variables filled by some
>communication routine.
>
>Hope this helps.
>-Ray
>
>
>
>On 12/20/12 08:48, Villa Andrea (RSE) wrote:
>> I'm experiencing some problems solving a linear system with AztecOO in
>>a parallel environment. I've built a square
>> matrix with a non-overlapping rowMap, the same rowMap is used to set
>>the rangeMap and the domainMap using the
>> fillComplete method. The colMap is not specified.
>> The right hand side has the same rowMap as the matrix.
>>
>> AztecOO aborts showing a rather obscure message: AZ_extract_comm_info:
>>Received elements must be stored after all 68
>> local elements.
>>
>> I appriciate any kind of suggestion.
>> Best regards. Andrea.
>>
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>-- 
>Ray Tuminaro                      phone: (925) 294-2564
>MS 9159                           fax:   (925) 294-2234
>Sandia National Laboratories      email: rstumin at sandia.gov
>PO Box 969                        http://www.cs.sandia.gov/~rstumin
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