[dune-pdelab] Dune reported error in newton.hh

[Jared Okiro]

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 Universität,
Universitätsplatz 02, Gebaude 02 / 115
39106 Magdeburg, Germany
Office Tel: +493916712660
Fax:        +493916718073
Mobile:     +4917657479787
Home Tel:   +4939155917376

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