[petsc-users] set block size on AMG systems

[Nico Schlömer]

> http://www.mcs.anl.gov/petsc/petsc-dev/docs/manualpages/Mat/MatSetBlockSize.html

Thanks!

> For complex-valued problems, you're likely better off using complex numbers.

Does PETSc support complex arithmetic natively? That'd be another
reason for getting complex-value support into FEniCS.

--Nico



On Sat, Mar 23, 2013 at 8:29 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
> http://www.mcs.anl.gov/petsc/petsc-dev/docs/manualpages/Mat/MatSetBlockSize.html
>
> PCML, PCHYPRE, and PCGAMG pay attention to this parameter if no richer
> information (like near-null spaces) is provided.
>
> For complex-valued problems, you're likely better off using complex numbers.
>
>
> On Sat, Mar 23, 2013 at 2:25 PM, Nico Schlömer <nico.schloemer at gmail.com>
> wrote:
>>
>> Hi,
>>
>> I've got this linear system consisting of 2x2 blocks (acutally coming
>> from a real-imaginary formulation of a complex-valued problem) and I'd
>> like to precondition the linear solves with AMG. Things are already
>> working well when taking the defaults, but I guess one could achieve
>> way better when telling AMG about the 2x2 structure. Trilinos' ML does
>> this by a parameter "PDE equations". -- Is there something comparable
>> in the PETSc world?
>>
>> --Nico
>
>