[petsc-users] Partitioning and AO problem

["Miguel A. Fernández"]

Thanks for your quick reply.

>> I'm using Petsc interface to ParMetis, as detailed in section 3.5 of the user's manual.
>> 
>> I have a problem with the creation of the AO mapps using the sentence 
>> 
>> AOCreateBasicIS(isg,PETSC NULL,&ao);
> 
> This line in the user's manual is incorrect. See Section 2.3.1 for a
> proper explanation.

OK, good to know ;).

>> where isg contains for each local node the new global (petsc) number of that node.
>> The problem is that the resulting AO map is inverted, and hence the results obtained with 
>> AOApplicationToPetsc and AOPetscToApplication are not correct. 
> 
> You have the arguments backward.


Yes, I agree, and this explains why the ApplicationToPetsc and PetscToApplication maps are inverted. 
The problem is that you can neither call AOCreateBasicIS(PETSC_NULL,isg,&ao);
since it seems that PETSC_NULL is only allowed in the second argument.

> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/AO/AOCreateBasic.html
> 
> It's not clear from your description above whether you have an
> "application ordering" or just a local to global map.

I have an application ordering and a petsc ordering, both global, in the spirit of Section 2.3.1. 
Here, the application ordering is the natural ordering (0, 1, 2, … ), resulting from a simple distribution 
of the nodes across processors, before partition with ParMetis.

Best,
Miguel



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