how to inverse a sparse matrix in Petsc?

[Barry Smith]

   They should be pretty much the same. In both cases the huge bulk of  
the time
is spent in the triangular solves.

    Barry

On Feb 4, 2008, at 8:04 AM, Dave May wrote:

> Hi,
>     Does anyone know how much faster (approximately) using  
> MatMatSolve is compared
> to using PCComputeExplicitOperator(), when the PC in the latter  
> function is defined to be LU?
>
> Cheers,
>     Dave.
>
>
> On Feb 5, 2008 12:10 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>    For sequential AIJ matrices you can fill the B matrix with the
> identity and then use
> MatMatSolve().
>
>    Note since the inverse of a sparse matrix is dense the B matrix is
> a SeqDense matrix.
>
>    Barry
>
>

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