Machine Learning, Deep Learning, Backpropagation, Artificial Intelligence, Differential Calculus.
which is the activation of the output neuron. A1 is in turn dependent on Z1.Derivative of A1 with respect to the Z1 is the derivative of the activation function.Then Z1 is actually dependent on the weights(W1)of the neural network.So, this was the pathway that linked Cost to the weights of the