[petsc-users] Some questions regarding VecNest type.

[Jed Brown]

On Wed, Oct 12, 2011 at 15:25, Vijay S. Mahadevan <vijay.m at gmail.com> wrote:

> What do you mean ? The blocks are formed in memory and handed over to
> the algebraic preconditioner (controlled at runtime). Why would the
> user have to change the preconditioner manually ? This made use of the
> block PC object in petsc-ext which I assume is replaced by FieldSplit
> ? I eventually do have to handle this elegantly and will need some
> input when I get there.
>
> If you are talking about the compile time switch, then yes, that was a
> little painful. But hopefully pure petsc will give me some peace !
>

I meant the two pieces of code. It's more to maintain and test. Needing to
choose at compile time is lame, but even if you could do it at run-time, it
would not be fun to maintain. In my opinion, we want one code where we can
do

-mat_type X -pc_type fieldsplit

and

-mat_type Y -pc_type lu

and have efficient data structures used in both cases.
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