[petsc-users] Questions about MatConvert BAIJ to AIJ

[Barry Smith]

> On Mar 18, 2015, at 3:14 PM, Chung-Kan Huang <ckhuangf at gmail.com> wrote:
> 
> 
> 
> On Wed, Mar 18, 2015 at 3:09 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> 
> > On Mar 18, 2015, at 3:07 PM, Chung-Kan Huang <ckhuangf at gmail.com> wrote:
> >
> > So I guess I misunderstood the meaning of " inplace conversion".
> > and what do MAT_INITIAL_MATRIX and MAT_REUSE_MATRIX do anyway?
> 
>   No you have not misunderstood it.
> 
> Currently
>    MAT_REUSE_MATRIX is only supported for inplace conversion, otherwise use
>    MAT_INITIAL_MATRIX.
> 
>   For testing purposes you can use MAT_INITIAL_MATRIX.
> 
> 
> I will try to convert the matrix in a new matrix using MAT_INITIAL_MATRIX. 
> while 
> MatConvert(J, MATAIJ, MAT_INITIAL_MATRIX, & A); 
> will convert the matrix and port the results into a new
> what does 
> MatConvert(J, MATAIJ, MAT_REUSE_MATRIX, & J);
> actually do?

   It puts the result into the J matrix you passed in, "replacing" the matrix that was there.

  Barry

> 
> Thanks,
>  
> 
> >
> >
> >
> >
> > On Wed, Mar 18, 2015 at 2:48 PM, Jed Brown <jed at jedbrown.org> wrote:
> > Chung-Kan Huang <ckhuangf at gmail.com> writes:
> >
> > > Yes, I was suprised that I can still use MatSetValuesBlocked after I did
> > > MatConvert MATBAIJ to MATAIJ.
> > >
> > > Then I just found the mat type is still seqbaij which means the MatConvert
> > > didn't work.
> > >
> > > This is how I did MatConvert
> > >
> > > MatConvert(J, MATAIJ, MAT_REUSE_MATRIX, & J);
> > >
> > > where J is my Jacobian matrix.
> >
> > Seems to me this should fail because you didn't MatConvert this matrix
> > yet.  Anyway, you should use MAT_INITIAL_MATRIX and put the result in a
> > new Mat.
> >
> >
> >
> > --
> > Cheers
> >
> 
> 
> 
> 
> -- 
> Cheers
>