dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

Great to see that it works!

Some suggestions/thoughts:

 - Maybe we could change the interface of NonlinearSolver to

   /// Solve nonlinear problem F(x) = 0
   uint solve(NonlinearFunction& F, Vector& x);

   so it looks more like the other solvers?

 - Maybe the class NonlinearFunction should not know anything about
   meshes and forms? It could just represent a nonlinear function
   and have two virtual functions F() and J() that a user can
   overload:

   class MyNonlinearFunction : public NonlinearFunction
   {
   public:
       ... F();
       ... J();
   };

   The functionality for PDEs can be put in a subclass of
   NonlinearFunction that we could call NonlinearPDE, or maybe
   just PDE if we assume that it is nonlinear in general.

   The nonlinear solver could then be used for other problems than
   PDEs, for example in the ODE solvers.

/Anders

On Tue, Nov 01, 2005 at 10:42:14AM +0100, dolfin@xxxxxxxxxx wrote:
> Commit from garth (2005-11-01 10:42 CET)
> -----------------
> 
> -Make FEM:nzsize public
> -Nonlinear solver is now working. Equations of the form F(u)=0 can be solved. Will add demo soon.
> 
> Nonlinear solver still requires some clean up. Issues include:
> - More general initialisation required.
> - Allow user to specify parameters for the Newton procedure.
> - Allow user to set parameters for the iterative solver (what's the plan for the GMRES class?).
> - Inhomogeneous Dirichlet boundary conditions. Some new functions are required in the class FEM to do this.
> - Addition of an incremental Newton procedure. PETSc functions exist for this.
> 
>   dolfin  src/kernel/fem/dolfin/FEM.h                1.19
>   dolfin  src/kernel/nls/NonlinearFunction.cpp       1.2
>   dolfin  src/kernel/nls/NonlinearSolver.cpp         1.11
>   dolfin  src/kernel/nls/dolfin/NonlinearFunction.h  1.2
>   dolfin  src/kernel/nls/dolfin/NonlinearSolver.h    1.8
> 
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-- 
Anders Logg
Research Assistant Professor
Toyota Technological Institute at Chicago
http://www.tti-c.org/logg/