[petsc-users] Conversion between AIJ & BAIJ

[Barry Smith]

> On Jan 21, 2015, at 2:58 PM, Chung-Kan Huang <ckhuangf at gmail.com> wrote:
> 
> 
> On Wed, Jan 21, 2015 at 2:35 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> 
>   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.
>  
>  
> I thought  MatSetValuesBlock can only work for BAIJ.
> So I can assign a block size to my AIJ matrix with MatSetBlockSize and then I can use MatSetValuesBlock afterward??

  Yes

>  
> Thanks,
>  
> Kan
> 
>   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
> >
> 
> 
> 
> 
> -- 
> Cheers
>