[petsc-users] How to efficiently represent a diagonal matrix?

[Fande Kong]

On Wed, Feb 14, 2018 at 4:35 PM, Smith, Barry F. <bsmith at mcs.anl.gov> wrote:

>
>   What are you doing with the matrix?
>

We are doing an explicit method. PDEs are discretized using a finite
element method, so there is a mass matrix. The mass matrix will be lumped,
and it becomes diagonal. We want to compute the inverse of the lumped
matrix, and also do a few of matrix-vector multiplications using  the
lumped matrix or  its inverse.

The specific implementation won't make this more efficient?


Fande,


>
>   We don't have a diagonal matrix but it would be easy to add such a beast
> if it was performance critical, which it probably isn't.
>
>   Barry
>
>
>
>
> > On Feb 14, 2018, at 3:57 PM, Fande Kong <fdkong.jd at gmail.com> wrote:
> >
> > Hi All,
> >
> > If  a matrix is always diagonal, what a good way to represent the
> matrix?  Still MPIAIJ, MPIBAIJ? Can we have a specific implementation for
> this?
> >
> >
> > Fande,
>
>
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