F is a second-order derivative. Comparing with gradient descent which is the first-order derivative, F is expensive to compute. That results in many research papers that try to approximate it (even reduce it back to the first-order derivative).

F is a second-order derivative. Comparing with gradient descent which is the first-order derivative, F is expensive to compute. That results in many research papers that try to approximate it (even reduce it back to the first-order derivative).

Deep Learning