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Dear PDELab Members,<br>
<br>
I am a new dune user. I am also not so experienced in C++, so still
learning both.<br>
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.<br>
<div id=":1jf">
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.<br>
<br>
<i>Dune reported error: NewtonLinearSolverError
[linearSolve:/homes/okiro/<wbr>DUNE/dune-svn/dune-pdelab/<wbr>dune/pdelab/backend/../newton/<wbr>newton.hh:174]:<br>
NewtonSolver::linearSolve(): Linear solver did not converge in 1
iterations.</i><br>
<br>
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:<br>
<br>
const residual [blocks=8,dimension=32]<br>
row 0 9.0e-01 9.0e-01 9.0e-01 9.0e-01<br>
row 4 9.0e-01 9.0e-01 9.0e-01 9.0e-01<br>
row 8 9.0e-01 9.0e-01 9.0e-01 9.0e-01<br>
row 12 9.0e-01 9.0e-01 9.0e-01 9.0e-01<br>
row 16 9.5e-01 9.5e-01 9.5e-01 9.5e-01<br>
row 20 9.5e-01 9.5e-01 9.5e-01 9.5e-01<br>
row 24 9.5e-01 9.5e-01 9.5e-01 9.5e-01<br>
row 28 9.5e-01 9.5e-01 9.5e-01 9.5e-01<br>
<br>
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.<br>
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?.<br>
<br>
Thank you.<br>
<br>
Kind regards,</div>
<pre class="moz-signature" cols="72">--
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</pre>
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