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

[Alp Kalpalp]

Hi,

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
"stefano_zampini/pcbddc-primalfixes"

These branches exist in "petsc" repo. Is it possible to merge petsc-dev and
"stefano_zampini/pcbddc-primalfixes"
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>
wrote:

> 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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