Rename derivative

chapters/functions.tex

@@ -1451,27 +1451,27 @@ \subsection{Using the Derivative Annotation}\label{using-the-derivative-annotati
   output Real z;
 algorithm
   $\ldots$
-  annotation(derivative(noDerivative = y) = f_der);
+  annotation(derivative(noDerivative = y) = h);
 end f;
 
-function f_der
+function h
   input Real x;
   input Real y;
   input Real x_der;
   output Real z_der;
 algorithm
   $\ldots$
-end f_der;
+end h;
 \end{lstlisting}
 This is useful if \lstinline!g! represents the major computational
 effort of \lstinline!fg!.
 
-Therefore \lstinline!f_der! indirectly includes the derivative with respect to \lstinline!y! as follows:
+Therefore \lstinline!h! indirectly includes the derivative with respect to \lstinline!y! as follows:
 \begin{eqnarray*}
 \frac{d}{dt}fg(x(t))&=&\frac{d}{dt}f(x(t),g(x(t)))\\
 &=&\frac{\partial f}{\partial x}\frac{dx}{dt}+\frac{\partial f}{\partial y}\frac{\partial g}{\partial x}\frac{dx}{dt}\\
 &=&\left(\frac{\partial f}{\partial x}+\frac{\partial f}{\partial y}\frac{\partial g}{\partial x}\right)\frac{dx}{dt}\\
-&=&\textrm{f\_der}(x,y)\frac{dx}{dt}
+&=&h(x,y)\frac{dx}{dt}
 \end{eqnarray*}
 \end{nonnormative}