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Tanh
The Tanh non-linearity has an S shape that is similar to the sigmoid non-linearity, but maps the input domain to an output range between [-1, 1]. In the same way as sigmoid, the gradient of Tanh is larger at its center, 0.0, but the gradient at the center is larger for the Tanh non-linearity, hence the derivatives are steeper and the gradient is stronger:
