Dmitry,
thanks for remind. I have a new question about PCASM / PCGASM:
can I get the restricted extension operators, which maps an overlapping
subdomain solution
to the global domain?
Thanks!
On May 15, 2012, at 3:29 PM, Dmitry Karpeev wrote:
> There are some additional minor fixes that mostly have to do with outputting
> the subdomain information with -pc_gasm_view_subdomains (in PCView()) and
> with -pc_gasm_print_subdomains (during PCSetUp()).
> You might want to pull those latest patches, but it won't interfere with your
> work if you don't use subdomain output.
>
> Thanks.
> Dmitry.
>
> On Tue, May 15, 2012 at 7:14 AM, Hui Zhang <mike.hui.zhang at hotmail.com>
> wrote:
> Dmitry,
>
> thanks for reply. I re-download the codes and tried it again and now it works
> correctly!
>
> Everything seems ok.
>
> Thanks,
> Hui
>
>
> On May 15, 2012, at 2:01 PM, Dmitry Karpeev wrote:
>
>> Hui,
>> I'm trying to reproduce this problem, unsuccessfully, so far.
>> One thing that looks odd is that the output below claims the PC is of type
>> "asm", even though you are running with -dd_type gasm. Could you verify
>> that's the correct output?
>>
>> Here's the output I get with
>> ${PETSC_DIR}/${PETSC_ARCH}/bin/mpiexec -np 1 ./gasm_test -n 64 -dd_type asm
>> -dd_ksp_view
>>
>> PC Object:(dd_) 1 MPI processes
>> type: asm
>> Additive Schwarz: total subdomain blocks = 2, user-defined overlap
>> Additive Schwarz: restriction/interpolation type - RESTRICT
>> Local solve is same for all blocks, in the following KSP and PC objects:
>> KSP Object: (dd_sub_) 1 MPI processes
>> type: preonly
>> maximum iterations=10000, initial guess is zero
>> tolerances: relative=1e-05, absolute=1e-50, divergence=10000
>> left preconditioning
>> using NONE norm type for convergence test
>> <snip>
>>
>> and with
>> ${PETSC_DIR}/${PETSC_ARCH}/bin/mpiexec -np 1 ./gasm_test -n 64 -dd_type gasm
>> -dd_ksp_view
>>
>> PC Object:(dd_) 1 MPI processes
>> type: gasm
>> Generalized additive Schwarz:
>> Restriction/interpolation type: RESTRICT
>> user-defined overlap
>> total number of subdomains = 2
>> number of local subdomains = 2
>> max number of local subdomains = 2
>> [0:1] number of locally-supported subdomains = 2
>> Subdomain solver info is as follows:
>> <snip>
>>
>> What convergence are you seeing with the two PC types? It should be the
>> same with 1 and 2 procs for both PCASM and PCGASM.
>>
>> Thanks.
>> Dmitry.
>>
>> On Tue, May 15, 2012 at 4:03 AM, Hui Zhang <mike.hui.zhang at hotmail.com>
>> wrote:
>> Dmitry,
>>
>> I got the newest petsc-dev and I run the test by
>>
>> mpirun -np 1 ./gasm_test -dd_type gasm -n 64 -dd_ksp_view
>>
>> which gives the following output
>>
>> PC Object:(dd_) 1 MPI processes
>> type: asm
>> Additive Schwarz: total subdomain blocks = 1, amount of overlap = 1
>> ^^^
>> note the above number, it should be
>> 2
>>
>> While PCASM has no such problem.
>>
>> Thanks,
>> Hui
>>
>>
>>
>>> Hui,
>>>
>>> The convergence issue should be resolved in the latest petsc-dev.
>>> I'm attaching a slightly modified gasm_test.c (reflecting some upcoming API
>>> changes)
>>> that should verify that.
>>>
>>> Let me know if it works for you.
>>> Thanks.
>>> Dmitry.
>>> On Fri, May 11, 2012 at 12:31 PM, Hui Zhang <mike.hui.zhang at hotmail.com>
>>> wrote:
>>> Hi Dmitry,
>>>
>>> thanks for useful hints. Good day!
>>>
>>> Hui
>>>
>>> On May 11, 2012, at 7:17 PM, Dmitry Karpeev wrote:
>>>
>>>> You can call PCSetUp(pc) on either ASM or GASM, and that will destroy and
>>>> recreate the matrices (including calling
>>>> your modification subroutine), but not the subdomains or the subdomain
>>>> solvers.
>>>> If you just want to modify the submatrices, you can call
>>>> PC(G)ASMGetSubmatrices() and modify the matrices it returns
>>>> (in the same order as the subdomains were set). That's a bit of a hack,
>>>> since you will essentially be modifying the PC's internal data structures.
>>>> As long as you are careful, you should be okay, since you already
>>>> effectively have the same type of access to the submatrices through the
>>>> Modify callback.
>>>>
>>>> Dmitry.
>>>>
>>>> On Fri, May 11, 2012 at 11:52 AM, Hui Zhang <mike.hui.zhang at
>>>> hotmail.com> wrote:
>>>> I just have a question about reuse of PCASM or PCGASM.
>>>> Suppose I have seted up the PCASM and related KSP and I solved one time.
>>>> Next for the same linear system (matrix and RHS), I just want PCASM modify
>>>> the submatrices (PCSetModifySubmatrices) in a different way, using the
>>>> same routine for modifying but with
>>>> different user context for the modifying routine.
>>>>
>>>> What can I do for this task? Currently, I destroy the KSP and
>>>> re-construct it. I guess
>>>> even for PCASM I can re-use it because the partition of subdomains remain
>>>> the same.
>>>>
>>>> Thanks!
>>>>
>>>>
>>>> On May 10, 2012, at 6:37 PM, Dmitry Karpeev wrote:
>>>>
>>>>> Hui,
>>>>> There've been several changes to PCGASM ahead of the new release.
>>>>> Let me go back and see if it affected the convergence problem.
>>>>> Dmitry.
>>>>>
>>>>> On Thu, May 10, 2012 at 4:16 AM, Hui Zhang <mike.hui.zhang at
>>>>> hotmail.com> wrote:
>>>>> Hi Dmitry,
>>>>>
>>>>> is there any news about PCGASM?
>>>>>
>>>>> thanks,
>>>>> Hui
>>>>>
>>>>> On Feb 20, 2012, at 6:38 PM, Dmitry Karpeev wrote:
>>>>>
>>>>>> Okay, thanks.
>>>>>> I'll take a look.
>>>>>>
>>>>>> Dmitry.
>>>>>>
>>>>>> On Mon, Feb 20, 2012 at 11:30 AM, Hui Zhang <mike.hui.zhang at
>>>>>> hotmail.com> wrote:
>>>>>> For reference, my results are attached.
>>>>>>
>>>>>> asm1.txt for asm with 1 process,
>>>>>> asm2.txt for asm with 2 processes,
>>>>>> gasm1.txt for gasm with 1 process, (with the iteration numbers different
>>>>>> from others)
>>>>>> gasm2.txt for gasm with 2 processes
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> thank you,
>>>>>> Hui
>>>>>>
>>>>>> On Feb 20, 2012, at 3:06 PM, Dmitry Karpeev wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Mon, Feb 20, 2012 at 12:59 AM, Hui Zhang <mike.hui.zhang at
>>>>>>> hotmail.com> wrote:
>>>>>>>
>>>>>>> On Feb 20, 2012, at 12:41 AM, Dmitry Karpeev wrote:
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Sun, Feb 19, 2012 at 3:08 PM, Hui Zhang <mike.hui.zhang at
>>>>>>>> hotmail.com> wrote:
>>>>>>>> I have a new problem: the results from ASM and GASM are different and
>>>>>>>> it seems
>>>>>>>> GASM has something wrong with SetModifySubMatrices. Numerical tests
>>>>>>>> are with
>>>>>>>> each subdomain supported only by one subdomain. There are no problems
>>>>>>>> when
>>>>>>>> I did not modify submatrices. But when I modify submatrices, there
>>>>>>>> are problems
>>>>>>>> with GASM but no problems with ASM.
>>>>>>>>
>>>>>>>> For example, I use two subdomains. In the first case each subdomain is
>>>>>>>> supported by
>>>>>>>> one processor and there seems no problem with GASM. But when I use run
>>>>>>>> my program
>>>>>>>> with only one proc. so that it supports both of the two subdomains,
>>>>>>>> the iteration
>>>>>>>> number is different from the first case and is much larger. On the
>>>>>>>> other hand
>>>>>>>> ASM has no such problem.
>>>>>>>>
>>>>>>>> Are the solutions the same?
>>>>>>>> What problem are you solving?
>>>>>>>
>>>>>>> Yes, the solutions are the same. That's why ASM gives the same results
>>>>>>> with one or
>>>>>>> two processors. But GASM did not.
>>>>>>> Sorry, I wasn't clear: ASM and GASM produced different solutions in the
>>>>>>> case of two domains per processor?
>>>>>>> I'm solving the Helmholtz equation. Maybe
>>>>>>> I can prepare a simpler example to show this difference.
>>>>>>> That would be helpful.
>>>>>>> Thanks.
>>>>>>>
>>>>>>> Dmitry.
>>>>>>>
>>>>>>>>
>>>>>>>> Dmitry.
>>>>>>>>
>>>>>>>>
>>>>>>>> On Feb 15, 2012, at 6:46 PM, Dmitry Karpeev wrote:
>>>>>>>>
>>>>>>>>> You should be able to.
>>>>>>>>> This behavior is the same as in PCASM,
>>>>>>>>> except in GASM the matrices live on subcommunicators.
>>>>>>>>> I am in transit right now, but I can take a closer look in Friday.
>>>>>>>>>
>>>>>>>>> Dmitry
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Feb 15, 2012, at 8:07, Hui Zhang <mike.hui.zhang at hotmail.com>
>>>>>>>>> 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
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>> <gasm_test.c>
>>
>>
>
>
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