[dune-pdelab] dune-pdelab Digest, Vol 28, Issue 2
Jared Okiro
jared.okiro at st.ovgu.de
Mon Jan 9 09:24:55 CET 2012
Dear Markus,
Thanks for the response. I printed the matrix after the time loop(just
after very few time steps). Here is the line of code that I used:
Dune::printvector(std::cout,unew.base(),"const residual","row",4,9,1);
Do you have any suggestion on how I can resolve this problem?.
Thank you.
--
Jared Ouma Okiro
Institute for Analysis and Numerics
Otto von Guericke Universität
Universitätsplatz 02, Gebaude 02 / 115
39106 Magdeburg, Germany
Office Tel: +493916712660
Fax: +493916718073
Mobile: +4917657479787
Home Tel: +4939155917376
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> Today's Topics:
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> 1. Dune reported error in newton.hh (Jared Okiro)
> 2. Re: Dune reported error in newton.hh (Markus Blatt)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 06 Jan 2012 16:31:31 +0100
> From: Jared Okiro <jared.okiro at st.ovgu.de>
> Subject: [dune-pdelab] Dune reported error in newton.hh
> To: dune-pdelab at dune-project.org
> Message-ID: <4F0713D3.7040404 at st.ovgu.de>
> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
>
> Dear PDELab Members,
>
> I am a new dune user. I am also not so experienced in C++, so still
> learning both.
> I have used the example DG code (Symmetric Weighted Interior Penalty
> Galerkin(SWIPG)) in pdelab/localoperator/convectiondiffusiondg.hh to
> solve a scalar nonlinear reaction-diffusion equation and it worked well.
> I have extended the code to solve a two component nonlinear
> reaction-diffusion system. However, at run time I get the error below:
> This error occurs when I evaluate the jacobian manually and also when I
> use numerical differentiation to determine the jacobian.
>
> /Dune reported error: NewtonLinearSolverError
> [linearSolve:/homes/okiro/DUNE/dune-svn/dune-pdelab/dune/pdelab/backend/../newton/newton.hh:174]:
> NewtonSolver::linearSolve(): Linear solver did not converge in 1
> iterations./
>
> When I print the matrix of the system with the coarse mesh and few
> iterations, I see that the matrix assembled is for the initial condition
> for each of the children and this does not change with even slight more
> iterations. The matrix looks like this:
>
> const residual [blocks=8,dimension=32]
> row 0 9.0e-01 9.0e-01 9.0e-01 9.0e-01
> row 4 9.0e-01 9.0e-01 9.0e-01 9.0e-01
> row 8 9.0e-01 9.0e-01 9.0e-01 9.0e-01
> row 12 9.0e-01 9.0e-01 9.0e-01 9.0e-01
> row 16 9.5e-01 9.5e-01 9.5e-01 9.5e-01
> row 20 9.5e-01 9.5e-01 9.5e-01 9.5e-01
> row 24 9.5e-01 9.5e-01 9.5e-01 9.5e-01
> row 28 9.5e-01 9.5e-01 9.5e-01 9.5e-01
>
> I suspect the error is in my local operator assembly. I would be
> grateful if someone could assist me resolve this error. I can provide
> the local operator if possible.
> Can the example DG code above be used to solve a system when both
> components are selected simultaneously or it can only be used to solve a
> system component by component?.
>
> Thank you.
>
> Kind regards,
>
> --
> Jared Ouma Okiro,
> Institute for Analysis and Numerics,
> Otto-von- Guericke Universit?t,
> Universit?tsplatz 02, Gebaude 02 / 115
> 39106 Magdeburg, Germany
> Office Tel: +493916712660
> Fax: +493916718073
> Mobile: +4917657479787
> Home Tel: +4939155917376
>
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> ------------------------------
>
> Message: 2
> Date: Fri, 6 Jan 2012 20:54:14 +0100
> From: Markus Blatt <markus at dr-blatt.de>
> Subject: Re: [dune-pdelab] Dune reported error in newton.hh
> To: dune-pdelab at dune-project.org
> Message-ID: <20120106195414.GB2606 at dr-blatt.de>
> Content-Type: text/plain; charset=us-ascii
>
> Hey Jared,
>
> On Fri, Jan 06, 2012 at 04:31:31PM +0100, Jared Okiro wrote:
>> I have used the example DG code (Symmetric Weighted Interior Penalty
>> Galerkin(SWIPG)) in pdelab/localoperator/convectiondiffusiondg.hh to
>> solve a scalar nonlinear reaction-diffusion equation and it worked
>> well.
>> I have extended the code to solve a two component nonlinear
>> reaction-diffusion system. However, at run time I get the error
>> below: This error occurs when I evaluate the jacobian manually and
>> also when I use numerical differentiation to determine the jacobian.
>>
>> /Dune reported error: NewtonLinearSolverError
>> [linearSolve:/homes/okiro/DUNE/dune-svn/dune-pdelab/dune/pdelab/backend/../newton/newton.hh:174]:
>> NewtonSolver::linearSolve(): Linear solver did not converge in 1
>> iterations./
>>
>
> I would guess that the linear solver has real problems solving your
> equation. As it tried only 1 step, I assume that it somehow broke
> down.
>
>> When I print the matrix of the system with the coarse mesh and few
>> iterations, I see that the matrix assembled is for the initial
>> condition for each of the children and this does not change with
>> even slight more iterations. The matrix looks like this:
>>
>> const residual [blocks=8,dimension=32]
>> row 0 9.0e-01 9.0e-01 9.0e-01 9.0e-01
>> row 4 9.0e-01 9.0e-01 9.0e-01 9.0e-01
>> row 8 9.0e-01 9.0e-01 9.0e-01 9.0e-01
>> row 12 9.0e-01 9.0e-01 9.0e-01 9.0e-01
>> row 16 9.5e-01 9.5e-01 9.5e-01 9.5e-01
>> row 20 9.5e-01 9.5e-01 9.5e-01 9.5e-01
>> row 24 9.5e-01 9.5e-01 9.5e-01 9.5e-01
>> row 28 9.5e-01 9.5e-01 9.5e-01 9.5e-01
>>
>
> How did you print the matrix? It looks like it contains zero rows
> (only each 4th row has nonzeros). Additionally the dimension 32x4
> seems weired.
>
> Markus
>
> --
> Do you need more support with DUNE or HPC in general?
>
> Dr. Markus Blatt - HPC-Simulation-Software & Services http://www.dr-blatt.de
> Rappoltsweilerstr. 5, 68229 Mannheim, Germany
> Tel.: +49 (0) 160 97590858 Fax: +49 (0)322 1108991658
>
>
>
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