[petsc-users] Conversion between AIJ & BAIJ

[Barry Smith]

  You should likely just use AIJ. It's main gain is for MatSolve() anyways which you aren't using. As I noted you can use MatSetValuesBlock() with AIJ.

  Barry

> On Jan 21, 2015, at 2:29 PM, Chung-Kan Huang <ckhuangf at gmail.com> wrote:
> 
> 
> On Wed, Jan 21, 2015 at 2:15 PM, Matthew Knepley <knepley at gmail.com> wrote:
> On Wed, Jan 21, 2015 at 2:07 PM, Chung-Kan Huang <ckhuangf at gmail.com> wrote:
> 
> On Wed, Jan 21, 2015 at 2:01 PM, Matthew Knepley <knepley at gmail.com> wrote:
> On Wed, Jan 21, 2015 at 1:55 PM, Chung-Kan Huang <ckhuangf at gmail.com> wrote:
> 
> On Wed, Jan 21, 2015 at 1:44 PM, Matthew Knepley <knepley at gmail.com> wrote:
> On Wed, Jan 21, 2015 at 1:40 PM, Chung-Kan Huang <ckhuangf at gmail.com> wrote:
> Then A & AB are not longer the same matrix.  They become complete two individuals aren't they?
> If I do whatever to AB after AB is created the A is still the same old A and not going to be affected by the operations I do to AB.
> 
> Yes.
>  
>  
> What I am really looking for is a way to create two interfaces (one as AIJ and one as BAIJ) but they both refer to the same matrix.
> 
> Why would you ever want this? Why not just using BAIJ?
> As I mentioned in the beginning.  There are parts of the code gets benifit when AIJ is used and the other part gets benifit  if BAIJ is used.
>  
> For instance,
>  
> I'd like to use MatSetValuesBlocked but I also want to use ilu constructed by AIJ instead of BAIJ (our experience found ilu from BAIJ behaves funny sometimes.
> 
> If the blocks truly are dense, then ILU(0) is identical on both.
>  
> Unfortunately the life is not that easy.  The blocks are spares and we found ILU(1) works better for our case.
> And besides that is not the only reason I want to have AIJ & BAIJ interfaces, we have some code management issue and I am looking for short cut to unite them.
>  
> So go back to the original question the short answer is no way? 
> 
> Yes, it would not make sense.
> 
> What problem are you using ILU(1) for?
>  
> I am using it for flow simulation for reservoir problems. 
>  
> Some issues we found is that
> 1) for a * x = 0 it doesn't return x = 0
> 2) After compared ILU(1) with BAIJ against with ILU(1) with AIJ I found latter one is better.  I could not find anything wrong with my BAIJ version though.  However, experiences suggested that BAIJ's ILU(1) should be better.
>  
>  
> Thanks,
>  
> Kan
> 
>   Thanks,
> 
>      Matt
>  
> Thanks,
>  
> Kan
> 
>   Matt
>  
> Thanks,
>  
> Kan
> 
>   Thanks,
> 
>       Matt
>  
> Thanks,
>  
> Kan
> On Wed, Jan 21, 2015 at 1:20 PM, Matthew Knepley <knepley at gmail.com> wrote:
> On Wed, Jan 21, 2015 at 12:56 PM, Chung-Kan Huang <ckhuangf at gmail.com> wrote:
> Hi,
>  
> So if I do
>  
> Mat A, AB;
> MatCreateAIJ(comm,m,n,M,N,d_nz, d_nnz,o_nz, o_nnz, &A);
> MatConvert(A, MATBAIJ, MAT_INITAL_MATRIX, &AB);
> MatSetBlockSize(AB, bs)
> I can create AB as a BAIJ with block size of bs from A which is a AIJ matrix.
>  
> So from this point I can use both A and AB and they will mean the same matrix. Am I right?
> 
> Yes
>  
> At the end of the program do I only destory one of them or both?
> 
> Both
>  
> Do I need to worry about anything in terms of memory penalty?
> 
> It is twice the memory. Its another matrix.
> 
> Did you catch when Jed said you could jsut create the BAIJ up front?
> 
>   Thanks,
> 
>     Matt
>  
>  
> Thanks,
>  
> Kan
>  
>  
> On Tue, Jan 20, 2015 at 4:39 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> 
>   You can do a MatConvert() (requires another copy of the matrix) for the parts that benefit from BAIJ.
> 
>   Barry
> 
> > On Jan 20, 2015, at 4:33 PM, Chung-Kan Huang <ckhuangf at gmail.com> wrote:
> >
> > Hi,
> >
> > Does PETSc provide means for conversion between AIJ & BAIJ.
> >
> > My matrix is created as AIJ because it makes life easy for most part of the applications but some part of applications actually get some benefits with BAIJ.  So I wonder if a matrix can exist as two idenfities and I can use either format depend on which one is more convenient at run time.
> >
> > So in my case the block size is fixed and identical for all blocks.
> >
> >
> > Thanks,
> >
> >
> > Kan
> 
> 
> 
> 
> -- 
> Cheers
> 
> 
> 
> 
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
> 
> 
> 
> -- 
> Cheers
> 
> 
> 
> 
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
> 
> 
> 
> -- 
> Cheers
> 
> 
> 
> 
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
> 
> 
> 
> -- 
> Cheers
> 
> 
> 
> 
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener
> 
> 
> 
> -- 
> Cheers
>