(mathematics) Any function of a real variable whose value decreases as the variable increases.

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

(computing) A program or subroutine, provided by the user rather than being built into the system, that may return a value and may take input parameters.

(mathematics) Any function whose value may be computed using a Turing machine.

(mathematics) The function whose value is zero if its independent variable is negative, and one otherwise.

(physics) An approximation to a wave function made by taking a linear combination of simpler functions

(computing) A program, module or subroutine etc that returns the value of a defined function

(mathematics) A function of one real argument, whose value is zero when the argument is nonzero, and whose integral is one over any interval that includes zero.

(mathematics) A function derived from the probability distribution of a random variable.

(mathematics) A certain arithmetic function that is neither multiplicative nor additive. It is denoted by Λ(n) and defined as :𝛬(n)= log p mbox ifn=pᵏ mbox forsomeprimep mbox andintegerk>1,\0 mbox otherwise.