This partial function defines the interface of a function with one input and one output Real signal. The scalar functions of Modelica.Math.Nonlinear are derived from this base type by inheritance. This allows to use these functions directly as function arguments to a function, see, .e.g., Math.Nonlinear.Examples.
encapsulated partial function partialScalarFunction import Modelica; extends Modelica.Icons.Function; input Real u "Independent variable"; output Real y "Dependent variable y=f(u)"; end partialScalarFunction;