f(r) = r^2
\]</span> and the likelihood contributions are exactly those from a
Gaussian.</p></li>
<li><p>If <code>loss='huber'</code> then <span class="math inline">\(f\)</span> is the Huber’s <span class="math inline">\(\psi\)</span> function given by <span class="math display">\[
\psi_{c}(r) = \left\{ \begin{array}{l} r^2 &amp; \text{for} \,\, r \leq
c \\ c(2r-c) &amp; \text{otherwise} \end{array} \right\}
\]</span> which is quadratic/linear in the residuals below/above the
threshold determined by <span