> What is the solution that you end up converging to
I get the correct solution.
> , and what are the boundary conditions?
>
I have natural BCs everywhere ( dV/dn=0) so I don't force it explicitly.
Ata
> Thanks.
> Dmitry.
>
> On Mon, Jan 16, 2012 at 6:20 PM, Ataollah Mesgarnejad <amesga1 at
> tigers.lsu.edu> wrote:
> Dear all,
>
> I'm trying to use SNESVI to solve a quadratic problem with box constraints.
> My problem in FE context reads:
>
> (\int_{Omega} E phi_i phi_j + \alpha \epsilon dphi_i dphi_j dx) V_i -
> (\int_{Omega} \alpha \frac{phi_j}{\epsilon} dx) = 0 , 0<= V <= 1
>
> or:
>
> [A]{V}-{b}={0}
>
> here phi is the basis function, E and \alpha are positive constants, and
> \epsilon is a positive regularization parameter in order of mesh resolution.
> In this problem we expect V =1 a.e. and go to zero very fast at some places.
> I'm running this on a rather small problem (<500000 DOFS) on small number of
> processors (<72). I expected SNESVI to converge in couple of iterations (<10)
> since my A matrix doesn't change, however I'm experiencing a slow convergence
> (~50-70 iterations). I checked KSP solver for SNES and it converges with a
> few iterations.
>
> I would appreciate any suggestions or observations to increase the
> convergence speed?
>
> Best,
> Ata
>
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