[petsc-dev] Copy *SNES-struct deeply

[Barry Smith]

On Mar 4, 2013, at 10:43 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> 
> On Mon, Mar 4, 2013 at 10:36 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> So you save the solution at some time step. Then later in another part of the calculation, you time integrate the solution for a few time steps (from the saved time-step) to "fill in" the solution values you did not save, then you use the solutions for those several time steps, then you discard them.
> 
>    So the question has nothing to do with SNES. It has to do with a "deep copy" of TS? Or being able to "restart" TS at a saved time step? Capabilities we want to build towards, but thinking in terms of a deep copy of SNES is a red herring.
> 
> Indeed, but presumably Johannes is working with an application that uses SNES.

   Why would he be doing that? Surely it is better to use a TS integrator in PETSc rather than to roll your own? If we were missing a feature needed for his integrator from TS then we would gladly add it.

   Barry

>  
> 
>    So, assuming one is using a single time integrator (not changing the integration method for different times), shouldn't this already pretty much work?
> 
> Yes, that's why I asked what sort of changes he was trying to guard against. Saving an entire copy of the SNES for each problem is wasteful when by far the most common case is to reuse configuration in each solve.