Update cross_validation.rst.

python/doc/theory/meta_modeling/cross_validation.rst

@@ -403,15 +403,15 @@ We substitute the previous equation in the definition of the K-Fold MSE and get:
 
 .. math::
 
-    \widehat{\operatorname{MSE}}_{KFold} 
+    \widehat{\operatorname{MSE}}_{KFold}
     & = \frac{1}{k n_\ell} \sum_{\ell = 1}^k \sum_{j \in \mathcal{S}_\ell}
     \left[y^{(j)} - \hat{g}^{(-j)} \left(\boldsymbol{x}^{(j)}\right)\right]^2.
 
 This implies:
 
 .. math::
 
-    \widehat{\operatorname{MSE}}_{KFold} 
+    \widehat{\operatorname{MSE}}_{KFold}
     & = \frac{1}{n} \sum_{\ell = 1}^k \sum_{j \in \mathcal{S}_\ell}
     \frac{n}{k n_\ell} \left[y^{(j)} - \hat{g}^{(-j)} \left(\boldsymbol{x}^{(j)}\right)\right]^2.
 
@@ -427,7 +427,7 @@ for :math:`j = 1, ..., n`. Hence:
 
 .. math::
 
-    \widehat{\operatorname{MSE}}_{KFold} 
+    \widehat{\operatorname{MSE}}_{KFold}
     & = \frac{1}{n} \sum_{\ell = 1}^k \sum_{j \in \mathcal{S}_\ell} \left(\Delta^{(j)}\right)^2 \\
     & = \frac{1}{n} \sum_{j = 1}^n \left(\Delta^{(j)}\right)^2