[petsc-users] [Libmesh-users] Convergence rate for petsc virs

[Ataollah Mesgarnejad]

Dmitry,

On Aug 12, 2012, at 3:13 AM, Dmitry Karpeev <karpeev at mcs.anl.gov> wrote:

> On Sat, Aug 11, 2012 at 6:36 PM, Subramanya Gautam Sadasiva <ssadasiv at purdue.edu> wrote:
> Hi,
> I was trying the snes solver on the obstacle problem by modifying miscellaneous ex 7 and I get only linear convergence times.Is this what is expected from the virs solver?
> Yes, in the sense that you can't expect Newton's typical quadratic convergence: you are not using Newton's method in the usual sense,
> since the linear (and, in a sense, the nonlinear) problem you are solving changes every time the coincidence set changes.

You see this is really bad for a case like mine where essentially I am solving a quadratic problem with box constraints (Jac and Constraints are constant during each solve). Is there anything we can do to use this structure shouldn't we be able to get a quadratic convergence ?

Thanks,
Ata

> 
> Dmitry. 
> THanks,
> Subramanya
> 
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