Baer functions B p q {\displaystyle B_{p}^{q}} and C p q {\displaystyle C_{p}^{q}}, named after Karl Baer, are solutions of the Baer differential equation d 2 B d z 2 + 1 2 [ 1 z − b + 1 z − c ] d B d z − [ p z + q ] B = 0 {\displaystyle {\frac {d^{2}B}{dz^{2}}}+{\frac {1}{2}}\left[{\frac {1}{z-b}}+{\frac {1}{z-c}}\right]{\frac {dB}{dz}}-\left[{\frac {pz+q}{}}\right]B=0} which arises when separation of variables is applied to the Laplace equation in paraboloidal coordinates. Wikipedia