These functions provide information about the Hjorth
distribution with location parameter equal to m, dispersion equal
to s, and family parameter equal to f: log hazard.
(See `rmutil` for the d/p/q/r boxcox functions density,
cumulative distribution, quantiles, and random generation).
The Hjorth distribution has density
$$
f(y) = (1+\sigma y)^{-\nu/\sigma} \exp(-(y/\mu)^2/2)
(\frac{y}{\mu^2}+\frac{\nu}{1+\sigma y})$$
where \(\mu\) is the location parameter of the distribution,
\(\sigma\) is the dispersion, and \(\nu\) is the family
parameter.