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This package contains the problem definition of systems of convection-diffusion-reaction equations. The system is given in the following form which is suited for a fixed-point iteration:

*-div(a(x,u_old,nabla u_old) nabla u)
+ div(b(x,u_old,nabla u_old) u) +
+ c(x,u_old,nabla u_old) nabla u +
+ r(x,u_old,nabla u_old) u
= f(x,u_old, nabla u_old)
- div(g(x,u_old, nabla u_old))
- div(a(x,u_old,nabla u_old) h(x,u_old, nabla u_old)) *

where *u:G to R^N*. Note that the last two terms are introduced in
the variational formulation and imply a natural Neumann boundary condition
*derivative{u}{n} = (g+a h) cdot n* at boundaries where no Dirichlet
constraints are posed.

- Class:
**<ELLSYS-PROBLEM>** -
Systems of convection-diffusion-reaction equations. The coefficients should be vector-valued functions in this case.

Superclasses: <PDE-PROBLEM>

- Function:
**ELLSYS-MODEL-PROBLEM**`DOMAIN``COMPONENTS`&KEY`A``B``C``D``R``F``G``H`(`DIRICHLET``NIL``DIRICHLET-P`)`INITIAL``SIGMA``EVP``PROPERTIES``DERIVED-CLASS` -
Generates a rather general elliptic problem on the given domain.

- Function:
**ISOTROPIC-DIFFUSION**`DIM``VALUES` -
Returns a sparse diagonal diffusion tensor with isotropic diffusion in each component.

`value`should be a vector or a number and contains the amount of diffusion in each component.

- Function:
**LINEARIZATION**`REACTION-JET` -
Returns a list of two functions namely

*u mapsto R(u)-DR(u)u*and*u mapsto -DR(u)*which can be used directly in the discretization as source and reaction term.

- Function:
**NR-OF-COMPONENTS**`PROBLEM` -
Returns the number of components for

`problem`.