ACCURATE COMPUTATION OF INDIVIDUAL AND TABLES OF 3-J AND 6-J SYMBOLS

By rewriting the formulas for 3-j and 6-j symbols in terms of several possible alternating binomial sums, it is possible to calculate these quantities quickly and accurately, often exactly, using floating point operations. The binomial sums can be calculated by direct summation o r by recursion. A simple method for uniquely parameterizing the well-k nown Regge symmetries of the 3-j and 6-j symbols makes it possible to systematize the choice of the smallest magnitude binomial sum (which e nhances the accuracy of floating point calculations and speeds up exac t calculations using large integer routines). Formulas for special cas es of the 3-j symbols enable the construction of recursion sequences w hich are often substantially faster than direct summation, especially for very large angular momentum arguments. For both 3-j and 6-j symbol s, recursion offers several advantages over direct summation in exact calculations and for calculating tables. (C) 1998 Published by Elsevie r Science B.V.