(physics) A function, denoted by Ai(x), that is a solution to the Airy equation.

(mathematics) a type of function used in the analysis of inhomogeneous differential equations.

(mathematics, statistics) A sigmoid function giving the probability that a measurement, under the influence of normally distributed errors with standard deviation, is within a certain distance from the mean value.

(mathematics, cryptography) A function that is easy to compute in one direction but difficult to compute in the opposite direction (finding its inverse) without special information.

(mathematics) A function whose domain is the empty set.

(mathematics) The signum function.

(mathematics) A function that maps a real number to the largest integer that is not greater than it.

Synonym of ceiling function

(mathematics) A function that maps a real number to the smallest integer that is no smaller than it.

(computing theory) One of the simplest and earliest examples of a total computable function that is not primitive recursive.