How to implement implicit methods in partial differential equations in matlab pdepe?

Hello,

Refer to the above cited subject, I'm using pdepe for solving a complex partial dieeferntial equation. I'm not sure if matlab uses explicit or implicit method internally. However, at the right bondary for which I'm using newmann bc, I'm getting some erratic solutions which is not expected.

I'd like to know how to use implicit method in matlab, if you can show any example which can be referred, would help me.

[Torsten]

MATLAB uses the method-of-lines within "pdepe". Thus it uses finite-difference approximations for the spatial coordinate derivatives and an implicit ODE-solver (ODE15S) to solve the resulting system of ordinary differential equations in the grid points. Changes to the solver method are impossible. Maybe you should include your code and the equations you try to solve with initial and boundary conditions here so that we can see if you somewhere made a mistake in the problem set-up.

If you are still working on your old equation: My guess is that "pdepe" is not suited in this case.