[petsc-users] Conversion between AIJ & BAIJ

[Barry Smith]

  MatSetValuesBlocked  works fine for AIJ matrices. Just set the block size

> On 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.
>  
> 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
>