Installation instruction for the FONLL code.

The code has been developed on a Linux system. It should also work on
othe Unix platforms. You need GNU make. The CERN library are
needed if you want to use the PDFLIB package (third install option below).
LHAPDF is needed to install with the second option below.


--- For the impatient -------------

IF LHAPDF is already installed on your system AND lhapdf-config is in your
path, then just do

  tar zxf FONLL-1.3.1.tgz
  cd FONLL-1.3.1/Linux
  ./makefonlllha

Alternatively, follow one of the set of instructions below.


--- first option: proprietary PDF package ------

- Change to the directory FONLL/Linux (or to another directory you created)

- Execute makefonll to compile and link the executable (fonll)
  
- Unpack the FONLL/pdfdata.tgz archive, or provide for the following step 
  to be able to find the PDF datafiles in your specific location

- execute FONLL/pdfdata/linkpdf.sh in the directory from where you intend 
  to run the fonll executable. This creates links to the PDF datafiles 
  needed by hvqpdfpho.f
  
- the shell tests.com in FONLL/tests executes a few test runs. It takes
  about 8 minutes on a Pentium III 866 MHz and about 5 minutes on a 
  Pentium 4 1.7 GHz (with gcc-g77 2.96). Its output (testfonll.outlog) can 
  be compared to the file testfonll.outlog-vX.X. 
  In order to run, tests.com creates in its directory the links to the 
  PDF datafiles by running FONLL/pdfdata/linpdf.sh  
  These links and other auxiliary files are deleted at the end of the run.
  NB: the file .outlog is not erased at the begining of a run. If you run 
  the code twice with the same filename tag you'll find both outputs in 
  there.

  ---------------------- OR ---------------------------------------------

--- second option: LHAPDF ------

- Execute makefonlllha to compile and link with the LHAPDF parton
  distribution libraries package. This produces the executable fonlllha

  The LHAPDF libraries will have to be installed on your system,
  and their location set in the main FONLL/main/Makefile by editing
  the variable LIBSLHA
  
  ---------------------- OR ---------------------------------------------

--- third option: PDFLIB. Deprecated!!! ------

- makefonllpdl links instead to the PDFLIB package from the CERN libraries
  rather than to the library that comes with FONLL (hvqpdfpho), and 
  creates the executable fonllpdl
  
  The PDFLIB libraries will have to be installed on your system,
  and their location set in the main FONLL/main/Makefile by editing
  the variable LIBSPDL

  
