Symbolic Clebsch-Gordon coefficients/Wigner symbols and Implementing Addition of Spin Angular Momenta

by Sean Vig for SymPy

The current implementation of spin in Sympy covers single spin states and the operators that can act on them; however, there is no means of dealing with spin states in multiple particle systems, which requires Clebsch-Gordon/Wigner symbols. Sympy currently has functions capable of calculating Clebsch-Gordon coefficients numerically; this project will focus on implementing a symbolic means of manipulating these coefficients and expand the spin implementation to utilize these coefficients.