Squeeze functionIt is a function that squeezes a wide range of input into a smaller range. It is usually used as an activation function. There are mainly two types: Sigmoid function and TANH hyperbolic tangent function.

The Sigmoid function is a common squeezing function that can squeeze a large range of inputs into the (0,1) interval. Its function expression and shape are as follows:

TAHN hyperbolic tangent function is a variant of the Sigmoid function. Its value range is [-1, 1] and its domain is R. It is also a kind of squeezing function.