[petsc-users] HDF5 timestepping in PETSc 3.16

[Matthew Knepley]

On Tue, Oct 19, 2021 at 6:12 AM Matthew Knepley <knepley at gmail.com> wrote:

> On Mon, Oct 18, 2021 at 10:35 PM Adrian Croucher <
> a.croucher at auckland.ac.nz> wrote:
>
>> Any response on this?
>>
>> This is a bit of a showstopper for me - I can't upgrade to PETSc 3.16 if
>> it does not allow my users to read their HDF5 files created using
>> earlier versions of PETSc.
>>
>> So far I can't see a workaround. Possibly the timestepping functions
>> need some kind of optional parameter to specify what the default
>> timestepping attribute should be, if it's not present in the file
>> (rather than just assuming it's false)?
>>
>
> I will fix it. I think I can do it tomorrow. Class just started this week
> do it is hectic :)
>
> I think you are right. We should always write the attribute, but have it
> be false. We should
> interpret a missing attribute as an old file.
>

Okay, I think I have it. Can you look at this branch?

  https://gitlab.com/petsc/petsc/-/merge_requests/4483

There is now an option that lets you set the default timestepping behavior

  -viewer_hdf5_default_timestepping

I think that is what you want.

  Thanks,

     Matt


>   Thanks,
>
>      Matt
>
>
>> Regards, Adrian
>>
>> On 10/14/21 4:19 PM, Adrian Croucher wrote:
>> > hi
>> >
>> > I am just testing out PETSc 3.16 and making the necessary changes to
>> > my code. Amongst other things I now have to add a
>> > PetscViewerHDF5PushTimestepping() call before starting to output
>> > time-dependent results to HDF5 using a PetscViewer.
>> >
>> > I now also have to add this call before reading in sets of previously
>> > computed time-dependent results (for restarting a simulation from the
>> > results of a previous run).
>> >
>> > The problem with this is that if I try to read in the results of any
>> > previous run, computed with an earlier version of PETSc (< 3.16), an
>> > error is raised because the time-dependent datasets in the file do not
>> > have the 'timestepping' attribute.
>> >
>> > Is there something else I need to do to make this work?
>> >
>> > - Adrian
>> >
>> --
>> Dr Adrian Croucher
>> Senior Research Fellow
>> Department of Engineering Science
>> University of Auckland, New Zealand
>> email: a.croucher at auckland.ac.nz
>> tel: +64 (0)9 923 4611
>>
>>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
> https://www.cse.buffalo.edu/~knepley/
> <http://www.cse.buffalo.edu/~knepley/>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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