Uses the formula
$$r(w, t) = r(t) = f(t-\lfloor t \rfloor)$$
where \(f(t)\) is the probability density function of the beta distribution
(see see ?dbeta) with parameters shape1 = beta_a and shape2 = beta_b.
Because mizer measures time in years, \(t-\lfloor t \rfloor\)
gives the time within the year and so \(r(t)\) is a periodic function with
the period of one year.
See also
Other release functions:
seasonalBetaHazardRelease(),
seasonalGaussianRelease(),
seasonalVonMisesRelease()