Figure 18.39.2 (See in context.)Figure 18.39.2: Coulomb–Pollaczek weight functions, , (18.39.50) for , , and . For the weight function, red curve,
has an essential singularity at , as all derivatives vanish as ; the green curve is ,
to be compared with its histogram approximation in §18.40(ii). For the weight function, blue curve, is non-zero at ,
but this point is also an essential singularity as the discrete parts of the weight function of (18.39.51) accumulate as , .
