Editing Function theory

'''Function theory''' may refer to:

* Theory of functions of a real variable, the traditional name of [[real analysis]], a branch of mathematical analysis dealing with the real numbers and real-valued functions of a real variable
* Theory of functions of a complex variable, the historical name for [[complex analysis]], the branch of mathematical analysis that investigates functions of complex numbers
* [[Constructive function theory]], the study of the connection between the smoothness of a function and its degree of approximation
* [[Geometric function theory]], the study of geometric properties of analytic functions

{{mathematical disambiguation}}