[Trilinos-Users] [EXTERNAL] question about MueLu (AMG) setting

Ouchi Hisanao ouchi at joe.co.jp
Fri Jul 10 18:20:14 EDT 2015


Hi Andrey,

>Do you have coordinates available?

Yes, I can use my physical coordinates data for repartitioning in my
simulation.

In our 2D hydraulic fracturing simulation, each elements has four unknowns
(displacement of x and y, pore pressure, fracture fluid pressure). At that
case, if the number of elements is N, do I have to provide the element
positions of N elements?  In addition, how do I give the information that
each element has four unknowns.

> Also, how do you construct MueLu preconditioner?

I don't use Tpetra because I am using Aztecoo.
I construct MueLu preconditioner by MueLu::EpetraOperator.
In this case, how do I provide the coordinate information?
Could you show me an example code to provide the physical coordinates?

Hisanao






2015-07-10 16:52 GMT-05:00 Andrey Prokopenko <aprokop at sandia.gov>:

>  Oh, I see. In order to use repartitioning at the moment you have to
> provide the physical coordinates of nodes corresponding to degrees of
> freedom of the matrix you pass to MueLu. We require that information as we
> use geometric partitioning to do rebalancing.
>
> Do you have coordinates available? Also, how do you construct MueLu
> preconditioner? If it is through CreateTpetraPreconditioner, you can simply
> pass these coordinates as a 3rd argument.
>
> -Andrey
>
>
> On 07/10/2015 03:46 PM, Ouchi Hisanao wrote:
>
>   Hi Andrey,
>
>  Thank you very much for your reply.
>
>  According to your advice, I modified my input deck based on a new style
> (please see the bottom of my email) and simply add the following sentence
> as you suggested.
>
>  <Parameter name="repartition: enable" type="bool" value="true"/>
>
>  However, I could not execute my code successfully since the following
> error message appeared.
>
>  -------------- ---------------------------- error messeage
> -------------------------------------------
> terminate called after throwing an instance of
> 'MueLu::Exceptions::RuntimeError'
>   what():  CoordinatesTransferFactory::DeclareInput: (LevelID = 0) unable
> to find or generate requested data "Coordinates" with generating factory
> "null"
>     during request for data "    Coordinates" on level 0 by factory
> CoordinatesTransferFactory
>     during request for data "    Coordinates" on level 1 by factory
> RebalanceTransferFactory
>     during request for data "              P" on level 1 by factory
> NoFactory
>
> -----------------------------------------------------------------------------------------------------------
>
>  This error message appears not only in my program in my Ubuntu but also
> in the sample code in the MueLu virtual machine image distributed by Sandia
> as a tutorial. In the case of the MueLu virtual machine image, I just added
> the following sentence in the simplest example input deck  (n1_easy.xml)
> and executed the simplest example problem in the MueLu tutorial (Laplace 2D
> 50x50).
>
>  <Parameter name="repartition: enable" type="bool" value="true"/>
>
>  Do you have any idea to resolve this error?
>
>  Best regards,
>
>  Hisanao
>
>  ----------------------------- modified input deck
> -------------------------------------
> <ParameterList name="MueLu">
>
>    <Parameter name="verbosity" type="string" value="high"/>
>
>    <Parameter name="max levels" type="int" value="10"/>
>   <Parameter name="coarse: max size" type="int" value="10"/>
>
>    <Parameter name="multigrid algorithm" type="string" value="sa"/>
>   <Parameter name="sa: damping factor"  type="double" value="1.0"/>
>
>    <!-- Smoothing -->
>   <!-- Comment/uncomment different sections to try different smoothers -->
>   <Parameter name="smoother: type" type="string" value="ILUT"/>
>
>  <!-- Rebalancing -->
>   <Parameter name="repartition: enable" type="bool" value="true"/>
>
>    <!-- Aggregation -->
>   <Parameter name="aggregation: type" type="string" value="uncoupled"/>
>   <Parameter name="aggregation: min agg size" type="int" value="4"/>
>
>  </ParameterList>
>
>
>
>
>
>
>
>
>
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