Update title and presentation of elementary mathematical functions

chapters/operatorsandexpressions.tex

@@ -592,12 +592,9 @@ \subsection{Event Triggering Mathematical Functions}\label{event-triggering-math
 \end{semantics}
 \end{operatordefinition}
 
-\subsection{Built-in Mathematical Functions and External Built-in Functions}\label{built-in-mathematical-functions-and-external-built-in-functions}
+\subsection{Elementary Mathematical Functions}\label{built-in-mathematical-functions-and-external-built-in-functions}
 
-The functions listed below are built-in mathematical functions are available in Modelica
-and can be called directly without any package prefix added to the
-function name. They are also available as external built-in functions in
-the \lstinline!Modelica.Math! library.
+The functions listed below are elementary mathematical functions.  Tools are expected to utilize well known properties of these functions (derivatives, inverses, etc) for symbolic processing of expressions and equations.
 \begin{center}
 \begin{tabular}{l|l l}
 \hline