fix pi to \pi

Author: jiannanWang

beginner_source/examples_nn/polynomial_nn.py

@@ -4,7 +4,7 @@
 -----------
 
 A third order polynomial, trained to predict :math:`y=\sin(x)` from :math:`-\pi`
-to :math:`pi` by minimizing squared Euclidean distance.
+to :math:`\pi` by minimizing squared Euclidean distance.
 
 This implementation uses the nn package from PyTorch to build the network.
 PyTorch autograd makes it easy to define computational graphs and take gradients,

beginner_source/examples_nn/polynomial_optim.py

@@ -4,7 +4,7 @@
 --------------
 
 A third order polynomial, trained to predict :math:`y=\sin(x)` from :math:`-\pi`
-to :math:`pi` by minimizing squared Euclidean distance.
+to :math:`\pi` by minimizing squared Euclidean distance.
 
 This implementation uses the nn package from PyTorch to build the network.
 

beginner_source/examples_tensor/polynomial_numpy.py

@@ -4,7 +4,7 @@
 --------------
 
 A third order polynomial, trained to predict :math:`y=\sin(x)` from :math:`-\pi`
-to :math:`pi` by minimizing squared Euclidean distance.
+to :math:`\pi` by minimizing squared Euclidean distance.
 
 This implementation uses numpy to manually compute the forward pass, loss, and
 backward pass.

beginner_source/examples_tensor/polynomial_tensor.py

@@ -4,7 +4,7 @@
 ----------------
 
 A third order polynomial, trained to predict :math:`y=\sin(x)` from :math:`-\pi`
-to :math:`pi` by minimizing squared Euclidean distance.
+to :math:`\pi` by minimizing squared Euclidean distance.
 
 This implementation uses PyTorch tensors to manually compute the forward pass,
 loss, and backward pass.