About the Project
33 Coulomb FunctionsComputation

§33.25 Approximations

Cody and Hillstrom (1970) provides rational approximations of the phase shift {\sigma_{0}}\left(\eta\right)=\operatorname{ph}\Gamma\left(1+\mathrm{i}\eta\right) (see (33.2.10)) for the ranges 0\leq\eta\leq 2, 2\leq\eta\leq 4, and 4\leq\eta\leq\infty. Maximum relative errors range from 1.09×10⁻²⁰ to 4.24×10⁻¹⁹.