Neural Network Basics

1. What does a neuron compute?

   答案：A neuron computes a linear function (z = Wx + b) followed by an activation function

   解析：Correct, we generally say that the output of a neuron is a = g(Wx + b) where g is the activation function (sigmoid, tanh, ReLU, ...).

2. Consider the two following random arrays "a" and "b":

   a = np.random.randn(4, 3) # a.shape = (4, 3)
   b = np.random.randn(3, 2) # b.shape = (3, 2)
   c = a*b
   

   What will be the shape of "c"?

   答案：The computation cannot happen because the sizes don't match. It's going to be "Error"!

   解析：In numpy the "*" operator indicates element-wise multiplication. It is different from "np.dot()". If you would try "c = np.dot(a,b)" you would get c.shape = (4, 2).