[petsc-users] FETI-DP implementation and call sequence

Alp Kalpalp alpkalpalp at gmail.com
Thu Sep 4 06:42:12 CDT 2014


Although I am experienced on C++ development on windows by using SVN, I
need to learn too much things to use this algorithm I think.(petsc,
debugging in linux, git, hg etc.)
So, sorry for the rookie questions in advance.

You suggested me to use development version ----> petsc-dev (I believe I
will compile and use it similar to petsc version of it), however it seems
it has no branch named as "master", "next" or

These branches exist in "petsc" repo. Is it possible to merge petsc-dev and
petsc-dev is hg, petsc is git !

or am I get it totaly wrong! I am confused.

Could someone explain me the development hierarchy in petsc? what is
petsc-dev and why it has no branches?

On Wed, Sep 3, 2014 at 6:18 PM, Stefano Zampini <stefano.zampini at gmail.com>

> FETIDP is in PETSc as a byproduct of the BDDC preconditioner (one is the
> dual of the other) and it does not have its own classes so far.
> That said, you can experiment with FETI-DP only after having setup a BDDC
> preconditioner with the options and customization you prefer.
> Use http://www.mcs.anl.gov/petsc/petsc-dev/docs/manualpages/KSP/index.html for
> manual pages.
> For an 'how to' with FETIDP, please see
> src/ksp/ksp/examples/tutorials/ex.59.c as Jed told you, specifically look
> at ComputeKSPFETIDP for obtaining the FETIDP matrix F (implemented
> Matrix-free) and the optimal FETIDP dirichlet preconditioner. Once you have
> F, you can use PCBDDCMatFETIDPGetRHS and PCBDDCMatFetiDPGetSolution to
> obtain a right-hand side for the FETIDP system and a physical solution from
> the solution of the FETIDP system.
> I would recommend you to use the development version of the library and
> either use the ‘next’ branch or the ‘master' branch after having merged
> in the branch stefano_zampini/pcbddc-primalfixes. Note that ‘next’ also
> contains the new deluxe scaling operator for BDDC which is not available
> to use with FETI-DP.
> If you have any other questions which can be useful for other PETSc users,
> please use the mailing list; otherwise you can contact me personally.
> Stefano
> On Sep 3, 2014, at 5:19 PM, Jed Brown <jed at jedbrown.org> wrote:
> Matthew Knepley <knepley at gmail.com> writes:
> 1- Is it possible to complete a FETI-DP solution with the provided
> functions in current PetSc release?
> There is no FETI-DP in PETSc.
> Wrong.  There is PCBDDC, which has the same eigenvalues as FETI-DP.  You
> can enable it by configuring --with-pcbddc.  This will be turned on by
> default soon.  It is fairly new, so you should use the branch 'master'
> instead of the release.  It has an option to do FETI-DP instead of BDDC.
> See src/ksp/ksp/examples/tutorials/ex59.c.
> For either of these methods, you have to assemble a MATIS.  If you use
> MatSetValuesLocal, most of your assembly code can stay the same.
> Hopefully we can get better examples before the next release.  Stefano
> (the author of PCBDDC, Cc'd) tests mostly with external packages, but we
> really need more complete tests within PETSc.
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