Libfact uses pari/gp and provides functions to deal with generalized
factorial functions and related objects.

There are two documentations for the library in doc:
    - libfact-doc.pdf        a talkative documentation with references
                             and examples in gp-code

    - libfact-quickdoc.pdf   a quick documentation only listing and
                             explaining  proposed functions
                            
Building libfact is straightforward : just run make. 
It will produce three files :

    - a static library libfact.a
    - a shared library libfact.so 
    - a gp-script      libfact.gp

You can now use the library. Just include libfact.h in your source
files and link to the desired library. 
To use the library within a gp-session, just read "libfact.gp" 
within gp. 
You can move the script "libfact.gp" around but if you do so with 
the shared library file "libfact.so", don't forget to update the 
absolute path in the first line of the script "libfact.gp".