[petsc-users] PCGASMSetLocalSubdomains

[Hui Zhang]

> 
> On Feb 15, 2012, at 10:26 AM, Hui Zhang wrote:
> 
>> 
>> On Feb 15, 2012, at 5:18 PM, Barry Smith wrote:
>> 
>>> 
>>> try it
>> 
>> Yes, I'm trying.  Just one more question: why there is no *Get* LocalToGlobalMapping
>> so that when a Mat is with some LocalToGlobalMapping we can temporarily change with
>> another mapping and reset back to the original mapping.
> 
>  There is.   Perhaps it is only in petsc-dev
> 
> 
>   Barry

I found it. Thank you very much! By GetLocalToGlobalMapping, I also find that the
submat's from PCGASM has not been SetLocalToGlobalMapping() yet when ModifySubMatrices 
was called by PCGASM. Everything is ok and clear now. Thanks again!



> 
>> 
>>> 
>>> On Feb 15, 2012, at 10:07 AM, Hui Zhang wrote:
>>> 
>>>> On Feb 15, 2012, at 11:19 AM, Hui Zhang wrote:
>>>> 
>>>>> Hi Dmitry,
>>>>> 
>>>>> thanks a lot! Currently, I'm not using ISColoring. Just comes another question
>>>>> on PCGASMSetModifySubMatrices(). The user provided function has the prototype
>>>>> 
>>>>>  func (PC pc,PetscInt nsub,IS *row,IS *col,Mat *submat,void *ctx);
>>>>> 
>>>>> I think the coloumns from the parameter 'col' are always the same as the rows 
>>>>> from the parameter 'row'. Because PCGASMSetLocalSubdomains() only accepts 
>>>>> index sets but not rows and columns. Has I misunderstood something?
>>>> 
>>>> As I tested, the row and col are always the same. 
>>>> 
>>>> I have a new question. Am I allowed to SetLocalToGlobalMapping() for the submat's
>>>> in the above func()?
>>>> 
>>>> thanks,
>>>> Hui
>>>> 
>>>>> 
>>>>> thanks,
>>>>> Hui
>>>>> 
>>>>> 
>>>>> On Feb 11, 2012, at 3:36 PM, Dmitry Karpeev wrote:
>>>>> 
>>>>>> Yes, that's right.
>>>>>> There is no good way to help the user assemble the subdomains at the moment beyond the 2D stuff.
>>>>>> It is expected that they are generated from mesh subdomains.
>>>>>> Each IS does carry the subdomains subcomm.
>>>>>> 
>>>>>> There is ISColoringToList() that is supposed to convert a "coloring" of indices to an array of ISs,
>>>>>> each having the indices with the same color and the subcomm that supports that color. It is
>>>>>> largely untested, though.  You could try using it and give us feedback on any problems you encounter.
>>>>>> 
>>>>>> Dmitry.
>>>>>> 
>>>>>> 
>>>>>> On Sat, Feb 11, 2012 at 6:06 AM, Hui Zhang <mike.hui.zhang at hotmail.com> wrote:
>>>>>> About PCGASMSetLocalSubdomains(), in the case of one subdomain supported by
>>>>>> multiple processors, shall I always create the arguments 'is[s]' and 'is_local[s]'
>>>>>> in a subcommunicator consisting of processors supporting the subdomain 's'?
>>>>>> 
>>>>>> The source code of PCGASMCreateSubdomains2D() seemingly does so.
>>>>>> 
>>>>>> Thanks,
>>>>>> Hui
>>>>>> 
>>>>>> 
>>>>> 
>>>> 
>>> 
>>> 
>> 
> 
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