# Functions

The Functions element is a location for writing user defined functions that can be used in simplifying the definition of a SpaceTimeFunction. When used in writing a SpaceTimeFunction, the arguments of the function can be set to user defined constants and parameters. See the A6 Magnetron Modes Example for an example of the use of a Function. You have options to create your own User Defined function or use the built-in turn on function. The turn on function has the mathematical formula $$H(t)*0.5*(1 - \cos(\pi t / T))*H(T-t)$$ where $$H(t)$$ is the Heaviside Step Function.

kind (not editable): The kind of constant; a User Defined kind.

description: A string describing the function.

arguments: The arguments that are used in the expression. The function can contain any number of arbitrary arguments and is not limited to the default values of x,y.

expression: This is the user-supplied expression that is a function of the arguments given in the argument property. It can include any pre-defined Constants, Parameters, or Functions, as well as real numbers and Python operators.