> On Sep 9, 2015, at 4:07 PM, Xiangdong <[email protected]> wrote:
>
> Each time I call my Jacobian function, it generates the Jacoiban matrix from
> scratch by inserting entries.
You mean you create a new matrix? With MatCreate or MatCreateXXX()?
Why do this? Why not just reuse the one that is passed in? It will be more
efficient.
> The result of this assembling process gives the same nonzero pattern as in
> the previous iteration. Can SNES/KSP track this too?
If you are creating a new matrix, no.
Barry
>
> Thanks.
>
> Xiangdong
>
> On Wed, Sep 9, 2015 at 5:01 PM, Barry Smith <[email protected]> wrote:
>
> Mat now keeps track of its nonzero pattern. If you do not change the
> pattern by inserting values then SNES/KSP will automatically keep the same
> pattern and optimize for it.
>
> Barry
>
> > On Sep 9, 2015, at 3:57 PM, Xiangdong <[email protected]> wrote:
> >
> > Hello everyone,
> >
> > As mentioned in the 3.5 changes, MatStructure argument is removed from
> > SNESSetJacobian(). If each time, my Jacobian always has
> > same_nonzero_pattern. How do I pass this information to SNES or the KSP? I
> > only find reuse same preconditioner, but not reuse same pattern.
> >
> > Thank you.
> >
> > Xiangdong
>
>
