fixing issue#2168 (#3181)

Co-authored-by: Svetlana Karslioglu <svekars@meta.com>

Author: DeeExe

beginner_source/blitz/autograd_tutorial.py

@@ -191,23 +191,22 @@
 # .. math::
 #
 #
-#      J^{T}\cdot \vec{v}=\left(\begin{array}{ccc}
+#      J^{T}\cdot \vec{v} = m \cdot \left(\begin{array}{ccc}
 #       \frac{\partial y_{1}}{\partial x_{1}} & \cdots & \frac{\partial y_{m}}{\partial x_{1}}\\
 #       \vdots & \ddots & \vdots\\
 #       \frac{\partial y_{1}}{\partial x_{n}} & \cdots & \frac{\partial y_{m}}{\partial x_{n}}
 #       \end{array}\right)\left(\begin{array}{c}
 #       \frac{\partial l}{\partial y_{1}}\\
 #       \vdots\\
 #       \frac{\partial l}{\partial y_{m}}
-#       \end{array}\right)=\left(\begin{array}{c}
+#       \end{array}\right) = m \cdot \left(\begin{array}{c}
 #       \frac{\partial l}{\partial x_{1}}\\
 #       \vdots\\
 #       \frac{\partial l}{\partial x_{n}}
 #       \end{array}\right)
 #
 # This characteristic of vector-Jacobian product is what we use in the above example;
 # ``external_grad`` represents :math:`\vec{v}`.
-#