uh creates an object of class uh, which stores a U-shaped
hazard function.
print.uh prints an object of class uh.
A U-shape hazard function, as generalized by Wang and Fani (2018), is given
by
$$h(t) = \alpha + \sum_{j = 1}^k \nu_j(\tau_j - t)_+^p + \sum_{j = 1}^{m} \mu_j (t-\eta_j)_+^p,$$
where \(\alpha,\nu_j,\mu_j \ge 0\),
\(\tau_1 < \cdots < \tau_k \le \eta_1 < \cdots < \eta_m,\) and \(p \ge 0\) is the the spline degree which
determines the smoothness of the U-shaped hazard. As p increases, the family
of hazard functions becomes increasingly smoother, but at the same time,
smaller. When \(p = 0\), the hazard function is U-shaped, as
studied by Bray et al. (1967). When \(p = 1\), the hazard function
is convex, as studied by Jankowski and Wellner (2009a,b).
print.uh prints an object of class uh. While alpha,
upper and deg are printed as they are, tau and
nu are printed as a two-column matrix, and so are eta and
mu.