(mathematics) Any function whose value repeats after the regular addition of a period to its independent variable; i.e., a function ƒ such that, for some positive constant p, ƒ(x + p) = ƒ(x) for all x.

(mathematical analysis) A function whose codomain is a topological space and domain is a measurable space, with the property that the inverse image of every open set in its codomain is a measurable set in its domain.

(mathematics) A generalization of the indicator function for a fuzzy set which assigns a truth value (0 or 1) to each element.

(logic) An expression containing algebraic symbols that serve to represent words or other elements of a sentence or proposition

(mathematics, physics) A function which specifies the average density of atoms, molecules etc in three dimensions from a given point.

(computing) A function key whose function can be assigned by the user or by a program.

(mathematics) A function of a complex variable obtained by differentiating the logarithm of a gamma function; the digamma function / (physics) The Schrödinger wave function

(mathematics) a meromorphic function

(statistics) Any function used to obtain a set of samples from a given population

(physics) A function which is a solution of Schrödinger's wave equation; the psi function