What is ReLU in Machine Learning?
Definition
In machine learning, the following function is referred to as a Rectified Linear Unit.
$$ f(x) = x^{+} := \max \left\{ 0, x \right\} $$
Description
In electrical engineering, this is known as a ramp function. For a description and properties of the function itself, not from the perspective of its use as an activation function in machine learning, refer to the ramp function article.