Add that purity does not influence this.

chapters/operatorsandexpressions.tex

@@ -1420,6 +1420,7 @@ \subsection{Function Variability}\label{function-variability}
 The variability of function calls needs to consider both the variability of arguments directly given in the function and the variability of the used default arguments, if any.
 This is especially a concern for functions given as a short class, see \cref{inheritance-of-functions}.
 This has additional implications for redeclarations, see \cref{function-compatibility}.
+The purity of the function, see \cref{pure-modelica-functions}, does not influence the variability of the function call.
 
 \subsection{Constant Expressions}\label{constant-expressions}