Re: how to inverse a sparse matrix in Petsc?

[Barry Smith <bsmith@xxxxxxxxxxx>]

  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@xxxxxxxxxxx> 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