= Compiling the PDAF library =

The tutorial implementations in the directory `PDAFROOT/tutorial/` and the models implemented with PDAF in `PDAFROOT/models/` are setup to compile the PDAF library when the application is compiled. (Here `PDAFROOT/` is the root directory of the PDAF package)

The PDAF library, thus the core routines of PDAF and PDAF-OMI, can also be compiled separately. This is the common approach when one implements PDAF with some models in the online-coupled setup (see e.g. the directory `modelbindings`).

== Compiling PDAF for ensemble filters and smoothers ==

To compile PDAF for ensemble filters and smoothers, do the following:

{{{
   cd src/
   make PDAF_ARCH=<ARCH>
}}}
where `<ARCH>` is the filename of the computer-specific settings from the directory `PDAFROOT/make.arch/` without `.h`. A common choice is '''<ARCH>=linux_gfortran_openmpi'''.

The compilation with generate the PDAF library file '''PDAFROOT/lib/libpdaf-d.a'''. In addition several Fortran module files `*.mod` are generated in the directory `PDAFROOT/include/`. These will be used when compiling the application program coupled to PDAF.


== Compiling PDAF for 3D-Var methods ==

The 3D-Var methods implemented in PDAF use solver algorithms from external libraries (from the directory `external/`). 

To compile PDAF with full support for the analysis with 3D-Var schemes do the following:

{{{
   cd src/
   make pdaf-var PDAF_ARCH=<ARCH>
}}}
where `<ARCH>` is the filename of the computer-specific settings from the directory `PDAFROOT/make.arch/` without `.h`. A common choice is '''<ARCH>=linux_gfortran_openmpi'''.

The compilation with generate the PDAF library file '''PDAFROOT/lib/libpdaf-var.a'''. This library also includes the ensemble filters and smoothers.
In addition several Fortran module files `*.mod` are generated in the directory `PDAFROOT/include/`. These will be used when compiling the application program coupled to PDAF.


== Linking the PDAF library ==

To point to the PDAF include directory to ensure that `pdaf_interface_module` and the `PDAFomi` module are found, one should specificy
{{{
   -I${PDAFROOT}/include
}}}
Here `${PDAFROOT}` is the directory of the PDAF package. It can either be directly specified by replacing ${PDAFROOT} or one speficies PDAFROOT as a variable.

For linking the PDAF library for the ensemble schemes use
{{{
   -L${PDAFROOT}/lib -lpdaf-d
}}}
while in case of the PDAF library supporting the 3D-Var schemes use
{{{
   -L${PDAFROOT}/lib -lpdaf-var
}}}

Apart from the PDAF library, one also needs to specify the location of the BLAS and LAPACK libraries (for example by setting `-lblas -llapack` if the libraries are installed in standard directories)