

            Root-rational-fraction program package

                   Version 3.2 -- June 2009


This set of routines performs arithmetic on numbers whose squares
are rational fractions (possibly negative, so that the numbers may
be pure imaginary).  In particular, the theory of angular momentum
yields various numbers of this form (the Wigner 3j, 6j and 9j
symbols) and routines are provided for calculating them.

The routines can be used as a library and called by a suitable Fortran
program. Details of the routines are given in the documentation, which
is in the doc directory in the form of html files. Alternatively,
there is an interactive calculator program, rrfcalc, that reads input
from the terminal a line at a time and treats it as commands for a
calculator working in Reverse Polish Notation. The commands available
are described in rrfcalc.html.

To extract the files, put the compressed tarfile in a suitable
directory, and type
gunzip rrf-3.2.tar
tar xvf rrf-3.2.tar
The files will be extracted into a new subdirectory called rrf-3.2.
Change to this directory, check the Makefile to specify the Fortran 90
compiler that you wish to use, and run "make". If successful, the rrfcalc
executable will be found in the bin directory. If possible, use a
compiler that supports 16-byte (quad precision) real variables and
8-byte integers.

To test the interactive calculator, run "make test"; to test the
program more extensively, use "make test3j", "make test6j" and "make
test9j". The latter three tests take data files from the tests
directory and send their output there. The data files can be edited to
extend the scope of the tests, but this can increase the computation
time substantially and can produce very large output files.

The program has been fairly thoroughly tested in its original form and
has been used successfully on a number of problems, but some bugs
doubtless remain. I should appreciate being told about them. The
present version is a Fortran 90 version, and has been tested against
the original version and using the test programs provided. The program
is made available for use without any warranty as to its reliability
or accuracy, and all use must be at the user's own risk. The package
may be made available to third parties, provided that no charge is
made other than a nominal handling charge, and provided that all files
are exactly in the original form, without any enhancements or other
modifications. Any bug reports or suggestions for improvement may be
sent to me at the address below. I would particularly welcome
information about any difficulties that may be encountered in porting
the program to other platforms.





                                      A. J. Stone
                                      University Chemical Laboratory
                                      Lensfield Road
                                      Cambridge CB2 1EW,
				      U.K.

                                      email: ajs1@cam.ac.uk
				      
				      June 2009
