[petsc-users] Conditional Constraints

[Jed Brown]

On Sun, Jul 31, 2011 at 22:11, Vijay S. Mahadevan <vijay.m at gmail.com> wrote:

> I saw from the documentation that the GL methods were capable of
> handling DAE systems. But the intention of my question was about the
> usage of the newton solver with functional constraints (with VI) for a
> DAE since in a sense, the DAE systems are a composite of an ODE and a
> constraint. So I was curious whether we could use temporal methods
> that were not intended for DAEs but for stiff ODEs only and use the VI
> solver to augment/restrict the solution with constraints. The reason
> for this is due to the fact that in the creation of a stiff solver,
> there are additional coefficient constraints that need to be satisfied
> to be used for a DAE but this is less restrictive for solving ODEs.
>

Do you want equality or inequality constraints? Equality constraints are
naturally handled by writing a DAE. Inequality constraints would be handled
by VI. VI is not currently available through TS, but my understanding is
that Shri is looking into this and it will eventually be available there
too.
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