[petsc-users] Can a MatShell that operates on ghosted vectors work in place?

[Jed Brown]

On Mon, Aug 20, 2012 at 10:12 AM, Matthew Knepley <knepley at gmail.com> wrote:

> Personally, I think this is quite cumbersome compared to the Local/Global
> vector strategy we use in DM, and
> does not have any real advantages.
>

For example, storage for the ghost values is allocated for every vector
duplicated from a VecGhost (e.g. the entire Krylov basis). This isn't an
issue if you have large subdomains, but for smallish subdomains using
methods with a fat stencil, that can double the storage needed for the
Krylov basis.
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