add regularization for test_machine_tranlation

Author: chengduoZH

python/paddle/fluid/regularizer.py

@@ -176,7 +176,6 @@ def __call__(self, param, grad, block):
             dtype="float32", shape=param.shape, lod_level=param.lod_level)
 
         if grad.type == core.VarDesc.VarType.SELECTED_ROWS:
-            # add concat_rows
             decay = block.create_var(
                 dtype="float32",
                 shape=param.shape,

python/paddle/fluid/tests/book/test_machine_translation.py

@@ -181,7 +181,10 @@ def train_main(use_cuda, is_sparse, is_local=True):
     cost = pd.cross_entropy(input=rnn_out, label=label)
     avg_cost = pd.mean(cost)
 
-    optimizer = fluid.optimizer.Adagrad(learning_rate=1e-4)
+    optimizer = fluid.optimizer.Adagrad(
+        learning_rate=1e-4,
+        regularization=fluid.regularizer.L2DecayRegularizer(
+            regularization_coeff=0.1))
     optimize_ops, params_grads = optimizer.minimize(avg_cost)
 
     train_data = paddle.batch(