Because of the modular structure of the code it is possible to introduce completely new physics with comparatively little effort. Take a look at these subdirectories to add new features:

• boundary: add new boundary conditions
• mesh: geometry of the mesh
• fluxes: flux functions and reconstruction processes
• physics: change physical fluxes (i.e eigenvalues of the advection problem)
• sources: add new/modify existing source terms
• io: add support for new input/output data file formats

According to the OO-design patterns there is a generic module (e.g. geometry_generic) for almost any task. These modules can be considered as an interface between the basic modules (e.g. geometry_cartesian, geometry_polar, etc.) and the program. The data structures related to these modules can be found in the subdirectory "common". To add a new feature follow these four steps:

1. Create a new basic module in the particular subdirectory (e.g. geometry_mygeo.f90 in ./mesh) using the existing modules as a template.
2. Edit the generic module and add a USE instruction with your new module to the header.Then define a new flag as an integer constant (e.g. INTEGER, PARAMETER :: MYGEO = 100) and customize the generic subroutines and functions. There are SELECT .. CASE branch instructions in which the specific routines are called.
3. Add the new file to the local Makefile.am.
4. Modify your initilization file init.f90 to use the new feature (e.g. CALL InitMesh(Mesh,Fluxes,MYGEO,..)).
5. Rebuild the whole program by doing "make clean" first. Run "./bootstrap", "./configure" and "make" afterwards.