diff --git a/beginners/notebook-examples/chapter-4/2-training-model.ipynb b/beginners/notebook-examples/chapter-4/2-training-model.ipynb
index ebb3141..95d220c 100644
--- a/beginners/notebook-examples/chapter-4/2-training-model.ipynb
+++ b/beginners/notebook-examples/chapter-4/2-training-model.ipynb
@@ -166,7 +166,7 @@
     "# 损失函数采用最小二乘法，y_pred - y 是形如[47, 1]的向量。\n",
     "# tf.matmul(a,b,transpose_a=True) 表示：矩阵a的转置乘矩阵b，即 [1,47] X [47,1]\n",
     "# 损失函数操作 loss\n",
-    "loss_op = 1 / (2 * len(X_data)) * tf.matmul((y_pred - y), (y_pred - y), transpose_a=True)\n",
+    "loss_op = 1.0 / (2 * len(X_data)) * tf.matmul((y_pred - y), (y_pred - y), transpose_a=True)\n",
     "# 随机梯度下降优化器 opt\n",
     "opt = tf.train.GradientDescentOptimizer(learning_rate=alpha)\n",
     "# 单轮训练操作 train_op\n",