[Trilinos-Users] [EXTERNAL] Mikado: Easy access to solvers

[Bartlett, Roscoe A]

Nico,

It looks like Mikado is a duplicate of Stratimikos with the following differences:

1) Mikado uses C++11 features with boost::any to allow simpler specification of a Teuchos::ParameterList directly in C++.   It would be be fairly easy to take that conversion code and move it into Teuchos (the only hard part are the unit tests). But in reality, people should not have to recompile their application all the time to change solvers and preconditioners.  With Teuchos::ParameterList, you can supply an XML file and in the near future, there will be a YAML format supported (which is used by MueLu currently I think).

2) Mikado is hard-coded to several solvers and preconditioners but does not allow for extension.  It does not abide by the Open-Closed Principle (OCP).  (Stratimikos allows you to register new linear solvers and preconditioners at runtime.)

3) Mikado can’t build and install as part of a Trilinos build.  People have to build and install Trilinos first and then separately configure, build, and install.  After the refactoring TriBITS #63<https://github.com/TriBITSPub/TriBITS/issues/63> is complete, then it will be fairly easy to build and install a package like Mikado either with Trilinos (as an added package) or downstream from Trilinos as its own CMake project.  (Actually, you already do that as was demonstrated with the XSDKTrilinos package.  It is not that hard to do even now.)

4) Mikado his hard-coded to Tpetra.  It can’t accept  Epetra objects as well.

5) Mikado only supports solving a single linear system.  It does not take into account solving a sequence of similar linear systems, solving more than one linear systems at the same time that shares the basic structure (and perhaps preconditioners), etc.

I would argue that the identical Mikado interface could just be a thin wrapper around Stratimikos::DefaultLinearSolverBuilder and would be a much smaller amount of code and would allow for extension of new solvers and preconditioners at  runtime.  Would you be willing to discuss that option?  Actually, now is a good time to discuss this if you are interested.

Given the listed BSD -3Clause license, I think this type of thing would be possible.

Cheers,

-Ross






Dr. Roscoe A. Bartlett, PhD
Sandia National Laboratories
Trilinos Software Engineering and Integration Technologies Lead
Consortium for the Advanced Simulation of Light Water Reactors (CASL) Physics Integration Infrastructure Lead

From: Trilinos-Users [mailto:trilinos-users-bounces at trilinos.org] On Behalf Of Nico Schlömer
Sent: Tuesday, August 02, 2016 12:27 PM
To: trilinos-users at trilinos.org; Trilinos Developers List
Subject: [EXTERNAL] [Trilinos-Users] Mikado: Easy access to solvers

Hi everyone,

I've recently invested some time to make access to (Tpetra) solvers in Trilinos easier. Fruit of the labor: Mikado [1]. It has helped me a great deal, maybe the same is true for you.

As usual: Hints and suggestions welcome!

Cheers,
Nico

[1] https://github.com/nschloe/mikado
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