ABSTRACT
Suppose z0 is a simple pole of the function f : D → C. Let θ0 be some fixed angle, and suppse ! > 0. LetC((α) ≡ {z0+!eit : θ0 ≤ t ≤ θ0+α} be the circular arc subtending α radians of the circle of radius ! centered at z0 as shown in Figure 9.8. We will sometimes need to evaluate integrals of the form
f (z) dz
) . (9.30)
In such cases, the following result will be useful.