### A calculator program and subroutine library for working with numbers that are square roots of rational fractions

This program was originally written by Anthony Stone and Charles
Wood, and is intended primarily for the calculation of Wigner 3j, 6j
and 9j symbols, which occur in the theory of angular momentum, and for
performing elementary arithmetic with them. Further details of the
original implementation may be found in *Comp. Phys. Comm.* **21** (1980)
195. The source code is available as a compressed
tarfile (about 25 kbytes). As well as providing a stand-alone
calculator program, it provides a library of
Fortran 90 subroutines that manipulate numbers which can be
represented as square roots of rational fractions.

Version 4 of the program is a set of Fortran 90 modules and uses some of the additional facilities of Fortran 90.

RRFcalc is a program that reads input a line at a time and treats it as commands for a calculator working in Reverse Polish Notation. It is convenient for interactive use, but it can be used non-interactively by supplying a file of commands as standard input.