ics according to the expression
</p>

<div class="eqn">
<img src="eqn/spherharm2.png" alt="[eqn]"><!--MATH
\begin{equation*}
Y_{L,M}(\theta,\phi) =
(-1)^M
\sqrt{\frac{(2L+1)}{4\pi}\frac{(L-M)!}{(L+M)!}}
P_L^M(\cos\theta)
\mr{e}^{\ii M\phi}
\end{equation*}
-->
</div>

<p>
with the Condon-Shortley phase factor <img src="eqn/spherharm3.png" alt="[eqn]"><!--MATH $(-1)^M$--> and the associated Legendre polynomial <img src="eqn/spherharm4.png" alt="[eqn]"><!--MATH $P_L^M(z)$--> computed by <a class="esf" href="pl