Rectifier (neural networks)

In the context of artificial neural networks, the rectifier is an activation function defined as
where x is the input to a neuron. This is also known as a ramp function, and it is analogous to half-wave rectification in electrical engineering. This activation function has been argued to be more biologically plausible than the widely used logistic sigmoid (which is inspired by probability theory; see logistic regression) and its more practical counterpart, the hyperbolic tangent. The rectifier is, as of 2015, the most popular activation function for deep neural networks.