en.wikipedia.org/wiki/Function_(mathematics)

In mathematics, a function is a relation between a set of inputs and a set of permissible outputs with the property that each input is related to exactly one output.

www.mathsisfun.com/sets/function.html

But we are not going to look at specific functions ... ... instead we will look at the general idea of a function. Names. First, it is useful to give a function a name.

functions.wolfram.com

The world's largest collection of formulas and graphics about more than 300000 mathematical functions for the mathematics and science communities.

www.khanacademy.org/math/algebra/algebra-functions/evaluating-functions/v/what-is-a-function

In programming, the concept of functions came from the idea of functions in mathematics. How they are similar: In math: -You take some input values -You give ...

www.khanacademy.org/math/algebra/algebra-functions

Functions are mathematical entities that assign unique outputs to given inputs. Sounds simple? Think again! In this topic you will evaluate, graph, analyze, and ...

docs.microsoft.com/en-us/sql/t-sql/functions/mathematical-functions-transact-sql

Mar 15, 2017 ... The following scalar functions perform a calculation, usually based ... All mathematical functions, except for RAND, are deterministic functions.

dlmf.nist.gov

Foreword · Preface · Mathematical Introduction · 1 Algebraic and Analytic Methods · 2 Asymptotic Approximations · 3 Numerical Methods · 4 Elementary ...

tutorial.math.lamar.edu/Classes/Alg/FunctionDefn.aspx

This seems like an odd definition but we'll need it for the definition of a function ( which is the main topic of this section). However, before we actually give the ...

www.thefreedictionary.com/mathematical+function

Noun, 1. mathematical function - (mathematics) a mathematical relation such that each element of a given set (the domain of the function) is associated with an ...