HYPRE with multiple variables

[Barry Smith]

  From PETSc MPIAIJ matrices you need to set the block size of the matrix
with MatSetBlockSize(A,5) after you have called MatSetType() or 
MatCreateMPIAIJ(). Then HYPRE_BoomerAMGSetNumFunctions() is automatically called by PETSc.

   Barry

The reason this is done this way instead of as 
-pc_hypre_boomeramg_block_size <bs> is the idea that hypre will use the 
properties of the matrix it is given in building the preconditioner so
the user does not have to pass those properties in seperately directly
to hypre.


On Fri, 13 Apr 2007, Shaman Mahmoudi wrote:

> Hi,
> 
> int HYPRE_BoomerAMGSetNumFunctions (.....)
> 
> sets the size of the system of PDEs.
> 
> With best regards, Shaman Mahmoudi
> 
> On Apr 13, 2007, at 2:04 PM, Shaman Mahmoudi wrote:
> 
> > Hi Nicolas,
> > 
> > You are right. hypre has changed a lot since the version I used.
> > 
> > I found this interesting information:
> > 
> > int HYPRE_BOOMERAMGSetNodal(....)
> > 
> > Sets whether to use the nodal systems version. Default is 0.
> > 
> > Then information about smoothers:
> > 
> > One interesting thing there is this,
> > 
> > HYPRE_BoomerAMGSetDomainType(....)
> > 
> > 0 - each point is a domain (default)
> > 1 each node is a domain (only of interest in systems AMG)
> > 2 ....
> > 
> > I could not find how you define the nodal displacement ordering. But it
> > should be there somewhere.
> > 
> > I read the reference manual for hypre 2.0
> > 
> > With best regards, Shaman Mahmoudi
> > 
> > 
> > On Apr 13, 2007, at 1:40 PM, Nicolas Bathfield wrote:
> > 
> > > Dear Shaman,
> > > 
> > > As far as I could understand, there is a BoomerAMG’s systems AMG version
> > > available. This seems to be exactly what I am looking for, but I just
> > > don't know how to access it, either through PETSc or directly.
> > > 
> > > Best regards,
> > > 
> > > Nicolas
> > > 
> > > > Hi,
> > > > 
> > > > You want to exploit the structure of the model?
> > > > As far as I know, boomeramg can not treat a set of rows or blocks as
> > > > a molecule,  a so called block-smoother?
> > > > ML 2.0 smoothed aggregation does support it.
> > > > 
> > > > With best regards, Shaman Mahmoudi
> > > > 
> > > > On Apr 13, 2007, at 10:45 AM, Nicolas Bathfield wrote:
> > > > 
> > > > > Hi,
> > > > > 
> > > > > I am solving the Navier-stokes equations and try to use Hypre as
> > > > > preconditioner.
> > > > > Until now, I used PETSc as non-segregated solver and it worked
> > > > > perfectly.
> > > > > Things got worse when I decided to use Boomeramg (Hypre).
> > > > > As I solve a system of PDEs,  each cell is represented by 5 rows in my
> > > > > matrix (I solve for 5 variables). PETSc handles that without problem
> > > > > apparently, but the coarsening scheme of Boomeramg needs more input in
> > > > > order to work properly.
> > > > > 
> > > > > Is there an option in PETSc to tell HYPRE that we are dealing with a
> > > > > system of PDEs? (something like:  -pc_hypre_boomeramg_...)
> > > > > 
> > > > > 
> > > > > Thanks for your help.
> > > > > 
> > > > > Best regards,
> > > > > 
> > > > > Nicolas
> > > > > 
> > > > > 
> > > > > --
> > > > > Nicolas BATHFIELD
> > > > > Chalmers University of Technology
> > > > > Shipping and Marine Technology
> > > > > phone: +46 (0)31 772 1476
> > > > > fax:   +46 (0)31 772 3699
> > > > > 
> > > > 
> > > > 
> > > 
> > > 
> > > -- 
> > > Nicolas BATHFIELD
> > > Chalmers University of Technology
> > > Shipping and Marine Technology
> > > phone: +46 (0)31 772 1476
> > > fax:   +46 (0)31 772 3699
> > > 
> > 
>