nullspaces

[Matthew Knepley]

On 5/9/06, Yaron Kretchmer <yaronkretchmer at gmail.com> wrote:
>
> Hi all
> I have a matrix representing electrical currents (KCL). In my design,
> there are some elements which are totally isolated from the rest of the
> circuit, which means that they form the matrix's nullspace.
>
> My questions are:
> *) Can I use Petsc to derive the nodes which compose the nullspace
>

We do not have QR type algorithms in PETSc, but you could use LAPACK or
PLAPACK for dense matrices.

*) Can I then remove them from the KSP? If so, how?
>

You can use the MatNullSpace architecture to remove these components from a
solve.

    Matt

Thanks much
> Yaron
>
>



--
"Failure has a thousand explanations. Success doesn't need one" -- Sir Alec
Guiness
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