EasyCalculusca-243

Tanh Derivative Backprop

Problem

The hyperbolic tangent has derivative 1 - tanh(x)^2.

Given an upstream gradient grad and a scalar pre-activation x, return grad * (1 - tanh(x)^2).

Hint

The tanh derivative is largest at the origin and decays toward zero at saturation.

case 1

in: [1,0]

expected: 1

case 2

in: [2,1]

expected: 0.8399486832280523

case 3

in: [-1,0.5]

expected: -0.7864477329659274

case 4

in: [0,2]

expected: 0

Starter codePython

def tanh_backward(grad, x):
    # Your code here
    pass

4 test cases · run your code against them in the editor