== Compiling and linking user-defined code == 
[[TracNav(doc/userint/toc)]]

Users can add their own (modified) user-interface to a PALM-run by carrying out the following steps:\\\\
   1. Copy the appropriate default (empty) user-interface files {{{user_***.f90}}} to a directory of your choice, e.g.:
{{{
cd ~/palm/current_version
mkdir -p USER_CODE/example
cp trunk/SOURCE/user_***.f90  USER_CODE/example
}}}
      '''Attention: do not change the filenames! '''

   2. Set an additional path in the configuration file .mrun.config to allow mrun to find and include these files:
{{{
%add_source_path   $base_directory/USER_CODE/$fname
}}}
      The default configuration file ({{{trunk/SCRIPTS/.mrun.config.default}}}) already includes this setting.\\
   3. Modify the interface routines according to your needs.\\
   4. Start a PALM run by executing
{{{
mrun -d example ...
}}}
      The files {{{user_***.f90}}} will be automatically compiled within the job and will replace the respective {{{PALM}}}‘s default user-interface routines.\\\\

The above method with including {{{$fname}}} in the additional source path allows to use different user-interfaces for different runs at the same time. Just store the respective interface-files in subdirectories {{{USER_CODE/abcd}}}, {{{USER_CODE/cdef}}}, etc. and start '''mrun''' with option "{{{-d abcd}}}", "{{{-d cdef}}}", etc. \\\\
If the user wants to add additional routines, he/she can a) put them into the default user-interface file {{{user_additional_routines.f90}}} or b) can create new files in the additional source directory. These files must have names different from the default {{{PALM}}} source code files. In case of b), the user must also copy the default makefile into the additional source directory:
{{{
cp trunk/SOURCE/Makefile  USER_CODE/example
}}}
The makefile must be modified appropriately following the "make"-rules in order to allow the new files to be compiled.\\\\
'''The modified user-interface files cannot be pre-compiled by using mbuild! '''\\\\
While programming user-defined code, errors are frequently made. For possible ways of error tracing see [../../debug#err Debugging].