[petsc-users] An advice on a linear system solution

[Umut Tabak]

On 01/12/2015 05:58 PM, Matthew Knepley wrote:
> On Mon, Jan 12, 2015 at 10:57 AM, Umut Tabak <u.tabak at tudelft.nl 
> <mailto:u.tabak at tudelft.nl>> wrote:
>
>     On 01/12/2015 04:29 PM, Matthew Knepley wrote:
>
>         Fieldsplit block preconditioners can be used on this type of
>         matrix, but success obviously depends on the
>         analytic character of the operators.  In particular, if we
>         assume that we have great PCs for the diagonal,
>         then B is the most important variable, and we need to know
>         what the Schur complement
>
>     Dear Matt,
>     Thanks, I have a bit of difficult time understanding what you mean
>     by ¨great PCs¨ for the diagonal? Could you please rephrase it?
>
>
> My impression was that you knew how to solve the diagonal blocks, but 
> not the full system.
Thx for the swift reply, well, you mean directly or iteratively? I 
looked a bit more but I am not sure if that is possible iteratively or 
not, I guess it is not since the character of the blocks on the diagonal 
are not well suited to iterative solution techniques. Maybe I should 
look into field split documentation once more.
Thx,
Umut
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