.. _doc.environment.why:

What is the MARS environment
============================

**3 Directories**
  * MARS environment is composed by 3 directories :
          * **MARS_CONFIG** : for compilation and code modification by the user
          * **COMPILE_MARS** : where the compile code is (*The user doesn't need to go in this directory and he must not modify files otherwise user's changes might be lost*)
          * **RUN_MARS** : for run simulations by the user, and where there are input and output files

**3 scripts** 
  * **mkconfdir** : create the directories of a configuration (:ref:`doc.envir_commands`)
  * **makefile**  : manage the configuration (choice of rank, test case, previous configurations), and compile the code by calling Makefile.linux or Makefile.datarmor
  * **Makefile.linux or Makefile.datarmor** : MARS compilation with CPP keys 
 
**Reference code**
  * The originial code (reference code) is placed in the Reference directory **$HOMEMARS/..**  
  * which contains :
          * MARS sources,
          * Scripts of MARS environment,
          * Makefile for the compilation,
          * Input files as namelists and  '*'.dat (river.dat, outflow.dat…)
          * Documentation : manuals, faq
          * Module example (fortran)
          * Libraries (netcdf, io_netcdf)
          * Code rules
  * The directory **$HOMEMARS** is defined in the user file : **.cshrc**

**Available directories**

.. image:: FIG/PHYS/arbre_homemars.jpg