TSTrajectory supports checkpointing for multistage methods and can certainly be extended to multistep methods. But I doubt it is the best solution to Alfredo’s problem. Alfredo, can you elaborate a bit on what you would like to do? TSBDF_Restart is already using the previous solution to restart the integration with first-order BDF.
Hong(Mr.) > On Mar 9, 2022, at 4:24 PM, Jed Brown <[email protected]> wrote: > > Can you restart using small low-order steps? > > Hong, does (or should) your trajectory stuff support an exact checkpointing > scheme for BDF? > > I think we could add an interface to access the stored steps, but there are > few things other than checkpointing that would make sense mathematically. > Would you be up for making a merge request to add TSBDFGetStepVecs(TS ts, > PetscInt *num_steps, const PetscReal **times, const Vec *vecs) and the > respective setter? > > Alfredo J Duarte Gomez <[email protected]> writes: > >> Good morning PETSC team, >> >> I am currently using a TSBDF object, which is working very well. >> >> However, I am running into trouble restarting higher order BDF methods. >> >> My problem is highly nonlinear, and when restarted for higher order BDF >> methods (using the TSBDF_Restart function), wiggles appear in a specific >> region of the solution. >> >> Is there any way I can initialize the higher order BDF restart loading >> previous solutions from a data file? I took a look at the code, but there >> is no obvious way to do this. >> >> Thanks, >> >> -Alfredo >> >> -- >> Alfredo Duarte >> Graduate Research Assistant >> The University of Texas at Austin
