Fast and accurate evaluation of Wigner 3j, 6j, and 9j symbols using prime factorisation and multi-word integer arithmetic

Understand

We present an efficient implementation for the evaluation of Wigner 3j, 6j, and 9j symbols.

• These represent numerical transformation coefficients that are used in the quantum theory of angular momentum.
• They can be expressed as sums and square roots of ratios of integers.
• The integers can be very large due to factorials.