[petsc-users] Adaptive controllers in TS

[Jed Brown]

Miguel Angel Salazar de Troya <salazardetroya at gmail.com> writes:

> Thanks for your response
>
> I'm struggling with this problem because the literature is not clear for me
> on how to calculate the discrete adjoint with adaptive time stepping
> algorithms. They cover the details when automatic differentiation tools are
> used. They mention that because the time step depend on the solution, it
> also depends on the parameter. Hence, there are terms that represent the
> derivative of the time step w.r.t. the parameters. What it is confusing is
> that they mention these terms must be removed. I don't understand this. I'm
> planning to hard-code the discrete adjoint problem (and use the TS if
> possible).

Are they suggesting that the time step sizes for a given run should be
frozen (at least locally) so that you have consistent gradients for a
while?
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