Dmitry.

On Mon, Feb 20, 2012 at 11:30 AM, Hui Zhang <mike.hui.zhang@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@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@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@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@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