[petsc-dev] asm / gasm

[Mark Adams]

I have added a dummy IS for BCs to GASM and it works on one processor now.
(branch mark/gamg-agg-gasm)

It does not work in parallel.  I am guessing that GASM requires that the
union of the indices in the array of ISs, given to PCGASMSetSubdomains, be
only local equations (and all local equations).  Is that correct?

Mark



On Sun, Jun 26, 2016 at 3:09 PM, Mark Adams <mfadams at lbl.gov> wrote:

> GASM does assume the index set includes every equation in the matrix.  It
> should probably check this as it has pmat.
>
> I guess I can add these BC vertices in.
>
> On Sun, Jun 26, 2016 at 11:20 AM, Mark Adams <mfadams at lbl.gov> wrote:
>
>> Fande,
>>
>> An alternative debug path that may be simpler and direct, as it works
>> with master:  'make runex56' in ksp/examples/tutorials in
>> branch mark/gamg-agg-asm.
>>
>> This runs clean in valgrind (for me), I've added an ISView call to see
>> the data that causes the error, it runs on one processor, uses a 3^3 cell
>> grid (tiny), it exits cleanly with the error:
>>
>>  ....
>> 87 189
>> 88 190
>> 89 191
>> > [0]PETSC ERROR: --------------------- Error Message
>> --------------------------------------------------------------
>> > [0]PETSC ERROR: Argument out of range
>> > [0]PETSC ERROR: Index 144 at 42 location greater than max 144
>> [0]PETSC ERROR: #1 VecScatterCheckIndices_Private() line 39 in
>> /Users/markadams/Codes/petsc/src/vec/vec/utils/vscat.c
>> [0]PETSC ERROR: #2 VecScatterCreate() line 1227 in
>> /Users/markadams/Codes/petsc/src/vec/vec/utils/vscat.c
>> [0]PETSC ERROR: #3 PCSetUp_GASM() line 481 in
>> /Users/markadams/Codes/petsc/src/ksp/pc/impls/gasm/gasm.c
>>   ....
>>
>> This index 144 is very suspicious to me because there are 144 REAL dofs
>> in this test, 192 "gross" dofs, minus (48) boundary conditions. This
>> problem has just two aggregates with sizes 54 & 90 (=144). (I strip out the
>> BC vertices.)
>>
>> Maybe GASM is getting confused because I do not give it domains that
>> cover the entire mesh (I strip out BC vertices).  GASM thinks there are 144
>> equations in this system when in fact there are 192.
>>
>> It looks to me like GASM is working a space stripped of BCs but it is
>> using my indices that are in the full space.
>>
>> Mark
>>
>>
>>
>
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