[petsc-dev] Contribution proposal about the application of PCShell as left and right preconditioner

[Patrick Sanan]

Does something like the following not work to make a PR? I'm not a dev
but I assume it would be more convenient to have your changes there
for comment.

- on the bitbucket website, make your own public fork of petsc, which
ends up at https://bitbucket.org/mybbusername/petsc/
- If you haven't done so, get a local petsc repo tracking the main petsc repo
    git clone https://psanan@bitbucket.org/petsc/petsc.git
- add your fork as a second remote to your local petsc repo
    cd petsc
    git remote add myfork git at bitbucket.org:mybbusername/petsc.git
- make a branch for the PR
    git checkout master
    git pull
    git checkout -b mybbusername/mybranchname
 - apply your patch
    git am 0001-my-patch-name.patch
- Push the new branch to your fork
    git push -u myfork mybbusername/mybranchname
- on the bitbucket website for you fork, find your new branch and
create a PR (to master) back to the main petsc repo

On Sat, Jan 9, 2016 at 1:06 PM, Sylvain Mercier
<sylvainmercier85 at gmail.com> wrote:
> Dear PETSc team,
>
> During my phd thesis, I have worked on solving sequences of linear
> systems with slowly varying matrices using GMRES(restart). In
> particular, I have developed a preconditioning technique to improve
> the action of an existing "first-level preconditioner". This new
> method is usually applied as right preconditioner with a PCShell, although
> the first preconditioner is applied on the left.
>
> That is why I have developed routines in PETSc to be able to apply
> simultaneously a left and a right PCShells when we use a PC_SYMMETRIC
> PCSIDE. In fact, I have add two routines: PCShellSetApplySymmetricLeft and
> PCShellSetApplySymmetricRight (similarly to the routine PCShellSetApply).
>
> Moreover, I have added the possibility to use a PC_SYMMETRIC preconditioner
> within GMRES.
>
> I gently request your position on the integration of these developments in
> PETSc. I have some problems to provide a pull-request via a fork so I
> propose a patch. Let me know if you want extra integration work.
>
> Best regards,
> Sylvain.