Improve linear_model.rst : error on Huber function
The subscript of the Huber function (H_m) was not relevant:
it was written H_m but the index m was nowhere used later; it should have been epsilon instead.
@@ -1137,13 +1137,13 @@ The loss function that :class:`HuberRegressor` minimizes is given by
.. math::
- \underset{w, \sigma}{\min\,} {\sum_{i=1}^n\left(\sigma + H_m\left(\frac{X_{i}w - y_{i}}{\sigma}\right)\sigma\right) + \alpha {||w||_2}^2}
+ \underset{w, \sigma}{\min\,} {\sum_{i=1}^n\left(\sigma + H_{\epsilon}\left(\frac{X_{i}w - y_{i}}{\sigma}\right)\sigma\right) + \alpha {||w||_2}^2}
where
.. math::
- H_m(z) = \begin{cases}
+ H_{\epsilon}(z) = \begin{cases}
z^2, & \text {if } |z| < \epsilon, \\
2\epsilon|z| - \epsilon^2, & \text{otherwise}
\end{cases}
