Re: [Libmesh-users] Variable groups to use blocked matrix (*BAIJ)

[Roy S. <roy...@ic...>]

On Wed, 9 May 2018, John Peterson wrote:

> On Wed, May 9, 2018 at 11:56 AM, Linda G <li...@na...> wrote:
>
>> Dear Libmesh Users,
>>
>> We are trying to figure out how to set up a Stabilized NS FEM formulation
>> to work
>> in a blocked matrix fashion. After reading the documentation we realized
>> that this boils down to define a
>> variable group, but we could not find any example (even the Elasticity
>> ones) that uses the
>> block matrix (*BAIJ) feature.
>> Please remember that our formulation is stabilized, so we are using P1P1
>> and P2P2 for velocity and pressure.
>> Is the function to define variables groups a member of System class or
>> DofMap class?
>> Please if anyone has a working example, or teach us how to do it, we really
>> appreciate.
>>
>
> If I understand correctly, this should happen automatically if you have a
> System with 1 variable group that contains more than 1 var, provided that
> you configure libmesh with --enable-blocked-storage. The default is
> --disable-blocked-storage since I believe we ran into some issues while
> using this option in the past.

https://github.com/libMesh/libmesh/issues/703 is the only concrete
issue I can find, thanks to SourceForge mailing list changes breaking
old archive links.

We should probably track this down soon so we can at least upgrade
blocked-storage from "enable only explicitly" to "enable with
--enable-everything".  I haven't been testing --enable-blocked-storage
for a long time so it may have regressed even further.
---
Roy