
110 ◾ Lionel R. Watkins
To create a truly directional wavelet, all one requires is a smooth func-
tion
C
ψ
()
k
with support in a convex cone
in frequency space, with poly-
nomial behavior inside and with exponential decay [30, 34]. An example of
this type of wavelet is the Cauchy wavelet, Equation (3.49c). ...