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> >>>>>> 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 >>>>>>> >>>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>> >>>> >>>> >>> >>> >> >> > > -------------- next part -------------- An HTML attachment was scrubbed... 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