diff --git a/docs/chapter03_DL-basics/3.3_linear-regression-pytorch.md b/docs/chapter03_DL-basics/3.3_linear-regression-pytorch.md
index 9a608d096..8a79c6baa 100644
--- a/docs/chapter03_DL-basics/3.3_linear-regression-pytorch.md
+++ b/docs/chapter03_DL-basics/3.3_linear-regression-pytorch.md
@@ -48,7 +48,7 @@ tensor([[-2.7723, -0.6627],
         [ 0.2576, -0.2928],
         [ 2.0475, -2.7440],
         [ 1.0685,  1.1920],
-        [ 1.0996,  0.5106]]) 
+        [ 1.0996,  0.5106]])
  tensor([ 0.9066, -0.6247,  9.3383,  3.6537,  3.1283, 17.0213,  5.6953, 17.6279,
          2.2809,  4.6661])
 ```
@@ -68,7 +68,7 @@ class LinearNet(nn.Module):
     def forward(self, x):
         y = self.linear(x)
         return y
-    
+
 net = LinearNet(num_inputs)
 print(net) # 使用print可以打印出网络的结构
 ```
@@ -195,7 +195,7 @@ num_epochs = 3
 for epoch in range(1, num_epochs + 1):
     for X, y in data_iter:
         output = net(X)
-        l = loss(output, y.view(-1, 1))
+        l = loss(output, y.view(-1, 1)).sum()
         optimizer.zero_grad() # 梯度清零，等价于net.zero_grad()
         l.backward()
         optimizer.step()