Ramp function

The ramp function is a unary real function, whose graph is shaped like a ramp. It can be expressed by numerous definitions, for example '0 for negative inputs, output equals input for non-negative inputs'. The term 'ramp' can also be used for other functions obtained by scaling and shifting, and the function in this article is the unit ramp function (slope 1, starting at 0). The ramp function is a unary real function, whose graph is shaped like a ramp. It can be expressed by numerous definitions, for example '0 for negative inputs, output equals input for non-negative inputs'. The term 'ramp' can also be used for other functions obtained by scaling and shifting, and the function in this article is the unit ramp function (slope 1, starting at 0). This function has numerous applications in mathematics and engineering, and goes by various names, depending on the context. The ramp function (R(x) : ℝ → ℝ0+) may be defined analytically in several ways. Possible definitions are: The ramp function has numerous applications in engineering, such as in the theory of digital signal processing. In finance, the payoff of a call option is a ramp (shifted by strike price). Horizontally flipping a ramp yields a put option, while vertically flipping (taking the negative) corresponds to selling or being 'short' an option. In finance, the shape is widely called a 'hockey stick', due the shape being similar to an ice hockey stick. In statistics, hinge functions of multivariate adaptive regression splines (MARS) are ramps, and are used to build regression models. In machine learning, it is commonly known as the rectifier used in rectified linear units (ReLUs). In the whole domain the function is non-negative, so its absolute value is itself, i.e.