I apologize; please ignore my answer below. Use MatCreateShell() as indicated by Jed.
> On Dec 20, 2023, at 2:14 PM, Barry Smith <bsm...@petsc.dev> wrote: > > > >> On Dec 20, 2023, at 11:44 AM, Yi Hu <y...@mpie.de> wrote: >> >> Dear Jed, >> >> Thanks for your reply. I have an analytical one to implement. >> >> Best, Yi >> >> -----Original Message----- >> From: Jed Brown <j...@jedbrown.org> >> Sent: Wednesday, December 20, 2023 5:40 PM >> To: Yi Hu <y...@mpie.de>; petsc-users@mcs.anl.gov >> Subject: Re: [petsc-users] fortran interface to snes matrix-free jacobian >> >> Are you wanting an analytic matrix-free operator or one created for you >> based on finite differencing? If the latter, just use -snes_mf or >> -snes_mf_operator. >> >> https://petsc.org/release/manual/snes/#jacobian-evaluation >> >> Yi Hu <y...@mpie.de> writes: >> >>> Dear PETSc team, >>> >>> My solution scheme relies on a matrix-free jacobian in the SNES solver. I >>> saw the useful C interface like MatCreateSNESMF(), >>> DMSNESCreateJacobianMF(). I am wondering if you have the fortran >>> equivalence? > > You can use DMSNESCreateJacobianMF() (MatCreateSNESMF is not appropriate > when you are providing the operation). > > >>> >>> I think for my problem in the main program I need to do >>> DMDASNESsetJacobianLocal(DM, INSERT_VALUES, myJacobian, ctx, err_petsc). >>> Then in myJacobian() subroutine I have to create the operator from >>> DMSNESCreateJacobianMF(), and register my own MATOP_MULT from >>> MatShellSetOperation(). Am I correct? > > Not exactly. Do not use DMDASNESsetJacobianLocal() use > DMSNESCreateJacobianMF() to create a Mat J where you create the SNES and use > SNESSetJacobian() and pass the J matrix in along with myJacobian(). > >>> >>> Are these fortran subroutines available? I saw an example in ts module >>> as ex22f_mf.F90 which behaves similar as what I would like to do. Because I >>> would like to use ngmres, I then need to stay in the SNES. >>> >>> Thanks for your help. >>> >>> Best wishes, >>> Yi >>> >>> ------------------------------------------------- >>> Stay up to date and follow us on LinkedIn, Twitter and YouTube. >>> >>> Max-Planck-Institut für Eisenforschung GmbH Max-Planck-Straße 1 >>> D-40237 Düsseldorf >>> >>> Handelsregister B 2533 >>> Amtsgericht Düsseldorf >>> >>> Geschäftsführung >>> Prof. Dr. Gerhard Dehm >>> Prof. Dr. Jörg Neugebauer >>> Prof. Dr. Dierk Raabe >>> Dr. Kai de Weldige >>> >>> Ust.-Id.-Nr.: DE 11 93 58 514 >>> Steuernummer: 105 5891 1000 >>> >>> >>> Please consider that invitations and e-mails of our institute are only >>> valid if they end with …@mpie.de. >>> If you are not sure of the validity please contact r...@mpie.de >>> >>> Bitte beachten Sie, dass Einladungen zu Veranstaltungen und E-Mails >>> aus unserem Haus nur mit der Endung …@mpie.de gültig sind. >>> In Zweifelsfällen wenden Sie sich bitte an r...@mpie.de >>> ------------------------------------------------- >> >> >> ------------------------------------------------- >> Stay up to date and follow us on LinkedIn, Twitter and YouTube. >> >> Max-Planck-Institut für Eisenforschung GmbH >> Max-Planck-Straße 1 >> D-40237 Düsseldorf >> >> Handelsregister B 2533 >> Amtsgericht Düsseldorf >> >> Geschäftsführung >> Prof. Dr. Gerhard Dehm >> Prof. Dr. Jörg Neugebauer >> Prof. Dr. Dierk Raabe >> Dr. Kai de Weldige >> >> Ust.-Id.-Nr.: DE 11 93 58 514 >> Steuernummer: 105 5891 1000 >> >> >> Please consider that invitations and e-mails of our institute are >> only valid if they end with …@mpie.de. >> If you are not sure of the validity please contact r...@mpie.de >> >> Bitte beachten Sie, dass Einladungen zu Veranstaltungen und E-Mails >> aus unserem Haus nur mit der Endung …@mpie.de gültig sind. >> In Zweifelsfällen wenden Sie sich bitte an r...@mpie.de >> -------------------------------------------------
