Its purpose is to preallocate off-diagonal blocks, but unless you're
hard up against your memory capacity, I would skip that clumsy code and
use MatPreallocator.
"Ellen M. Price via petsc-users" writes:
> Hello again!
>
> For my multiphysics problem, I think a DMComposite might make the most
> s
Hello again!
For my multiphysics problem, I think a DMComposite might make the most
sense, since some variables are only defined in 1d (so any 2d
information is just wasting memory and CPU), while others have a full 2d
distribution. To tell PETSc how the two DMs should be coupled, it looks
like I
Smoothed aggregation mostly just cares about the near-null space
(MatSetNearNullSpace), which is a global property. Classical AMG uses
block size directly (number of dofs per C-point), but I'm not aware of
any implementation that supports variable block size. This would be a
research topic.
Marc
On Mon, Oct 28, 2019 at 12:37 PM Marco Cisternino via petsc-users <
petsc-users@mcs.anl.gov> wrote:
> Hi Stefano,
> thanks for your interest.
> Mainly, elliptic operators both in the context of methods in NS solvers
> and in the context of mesh deformation.
> I didn't think about AMG on each block
Hi Stefano,
thanks for your interest.
Mainly, elliptic operators both in the context of methods in NS solvers and in
the context of mesh deformation.
I didn't think about AMG on each block. What I was thinking about is an AMG
preconditioner aware about the variable size blocks.
I hope it is clear
Hello everybody.
We would like to setup an algebraic multi-grid block preconditioner and I would
like to be able to define custom blocks of variable sizes. Reading the
documentation, it seems that this can be achieved using the "PCGAMG"
preconditioner and defining the blocks with the function
"
