update sag solver docs (#10150)

patrick1011 · patrick1011 · commit 4bc025a27b8f · 2017-11-23T10:25:14.000Z
diff --git a/sklearn/linear_model/sag.py b/sklearn/linear_model/sag.py
@@ -131,7 +131,12 @@ def sag_solver(X, y, sample_weight=None, loss='log', alpha=1., beta=0.,
            *loss='multinomial'*
 
     alpha : float, optional
-        Constant that multiplies the regularization term. Defaults to 1.
+        L2 regularization term in the objective function
+        (0.5 * alpha * || W ||_F^2). Defaults to 1.
+
+    beta : float, optional
+        L1 regularization term in the objective function (beta * || W ||_1).
+        Only applied if is_saga set to True. Defaults to 0.
 
     max_iter : int, optional
         The max number of passes over the training data if the stopping
