[MRG+1] DOC fix sign in GBRT mathematical formulation
@@ -598,7 +598,7 @@ minimize the loss function :math:`L` given the current model
.. math::
F_m(x) = F_{m-1}(x) + \arg\min_{h} \sum_{i=1}^{n} L(y_i,
- F_{m-1}(x_i) - h(x))
+ F_{m-1}(x_i) + h(x))
The initial model :math:`F_{0}` is problem specific, for least-squares
regression one usually chooses the mean of the target values.
@@ -614,7 +614,7 @@ loss function:
.. math::
- F_m(x) = F_{m-1}(x) + \gamma_m \sum_{i=1}^{n} \nabla_F L(y_i,
+ F_m(x) = F_{m-1}(x) - \gamma_m \sum_{i=1}^{n} \nabla_F L(y_i,
F_{m-1}(x_i))
Where the step length :math:`\gamma_m` is chosen using line search:
