SpecDistrWeight is an S4 class that implements a
weighting function given by $$W_n(\alpha) := I{\alpha
\leq 0}$$.k the value $W_n(2\pi
(k-1)/n$ is stored [in a vector
values nested inside env] for
k=1,...,T. The number length(values) of
Fourier frequencies for which $W_n$ will be
evaluated may be set on construction or updated when
evoking the method getValues.