[petsc-users] Is sparsity of Vec exploited in MatMult?

[Matthew Knepley]

On Thu, Feb 9, 2012 at 8:09 AM, Hui Zhang <buyong.huier at gmail.com> wrote:

> Hi,
>
> Is sparsity of Vec exploited in MatMult? I'm implementing some domain
> decomposition
> methods. The residual is non-zero or significant only at very few nodes.
> Does
> MatMult knows that most entries of the Vec are zeros? Is there a threshold
> to
> regard an value as zero?
>

No.

  Matt


> Thanks,
> Hui




-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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