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Can we somehow use the PetscCheckPointer() in ALL our Fortran stubs to make
sure the user has passed a reasonable ierr arg?
Barry
Begin forwarded message:
> From: Jed Brown
> Subject: Re: [petsc-maint #126615] Problem, please help me
> Date: August 2, 2012 9:51:11 AM CDT
> To: petsc-
> How does one precondition a system like that? Presumably, the user may at
> best be able to provide a preconditioner for JF.
>
> If JF responds well to multigrid, then it may be possible to use AMG-KKT
> to coarsen the constraint Hessian, but how does MG perform for the sum
> JF + Hc? There i
gt; > subdifferential.
> >
> > Do you mean that the slacks are eliminated again in the linear algebra?
> What are the "subtle differences"?
>
>
> If you eliminate the slack variables, in the slack formulation, then you
> get
> a system that looks like the semismooth system, but with a different right
> hand side. Apparently, the difference in the right hand side leads to
> fewer Newton iterations in general. Not a big deal.
>
> Cheers, Todd.
>
>
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