EXPANSION OF JACOBI-POLYNOMIALS IN TERMS OF ORTHOGONAL FUNCTIONS

Polynomials P(n)alpha,beta(psi), where psi is the angle between the unit vectors r1 = (1, theta1, phi1) and r2 = (1, theta2, phi2), are given by two representations. The calculation of the coefficients in the suggested representations explicitly justifies the forms given by equations (6) and (12). The link between the two representations provides two interesting summation rules.