When an interpretive code string is used to define a function of a function class (YFunctionSeries or ParametricFunctionSeries), the string is compiled and the resulting code is dynamically included into the application. Execution speed will be the same as any other compiled code.

For simple, one-variable explicit functions, the YFunctionSeries class object is used. This object has one code property, FunctionCode. For YFunction objects, the independent variable is always assumed to be "x".

For parametric functions, a pair of equations must be defined using the ParametricFunctionSeries class object. This object has two properties, one for each coordinate. The properties, XFunctionCode and YFunctionCode accept code in which the independent variable is always assumed to be "t".