[petsc-users] PCGASMSetLocalSubdomains

[Barry Smith]

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

> 
>> 
>> 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
>>>>> 
>>>>> 
>>>> 
>>> 
>> 
>> 
>