Figure 19.17.8: ,
, .
Cauchy principal values are shown when .
The function is asymptotic to
as , and to
as .
As it has the limit .
When , it reduces to .
If , then it has the value
when , and
when .
See (19.20.10), (19.20.11), and
(19.20.8) for the cases , , and
, respectively.