Evaluates the Huber loss function defined as $$ f(r) = \left\{
\begin{array}{ll}
\frac{1}{2}|r|^2 & |r| \le c \\
c(|r|-\frac{1}{2}c) & |r| > c
\end{array}
\right. $$
$$$$
Usage
Huber(r, c = 1.345)
Arguments
r
a real number or vector.
c
a positive number. If the value is negative, it's absolute value will be used.