Rename math command \pdfrac -> \udfrac (and introduce \pdfrac for com…

…parison)

chapters/functions.tex

@@ -1334,11 +1334,11 @@ \subsection{Using the Derivative Annotation}\label{using-the-derivative-annotati
 \begin{align*}
 (\ldots,\, y(t),\, \ldots) &= \text{\lstinline!foo0!}(\ldots,\, x(t),\, b,\ldots)
 \intertext{implies that:}
-(\ldots,\, \pdfrac{y(t)}{t},\, \ldots) &=
-\text{\lstinline!foo1!}(\ldots,\, x(t),\, b,\, \ldots,\,  \ldots,\, \pdfrac{x(t)}{t},\, \ldots)
+(\ldots,\, \udfrac{y(t)}{t},\, \ldots) &=
+\text{\lstinline!foo1!}(\ldots,\, x(t),\, b,\, \ldots,\,  \ldots,\, \udfrac{x(t)}{t},\, \ldots)
 \\
-(\ldots,\, \pdfrac[2]{y(t)}{t},\, \ldots) &=
-\text{\lstinline!foo2!}(\ldots,\, x(t),\, b,\, \ldots,\, \pdfrac{x(t)}{t},\, \ldots,\, \ldots,\, \pdfrac[2]{x(t)}{t},\, \ldots)
+(\ldots,\, \udfrac[2]{y(t)}{t},\, \ldots) &=
+\text{\lstinline!foo2!}(\ldots,\, x(t),\, b,\, \ldots,\, \udfrac{x(t)}{t},\, \ldots,\, \ldots,\, \udfrac[2]{x(t)}{t},\, \ldots)
 \end{align*}
 \end{example}
 

mlsshared.sty

@@ -157,14 +157,22 @@
 
 % Misc math
 \newcommand{\ud}{\mathrm{d}}
-\newcommand{\pdfrac}[3][\@nil]{%
+\newcommand{\udfrac}[3][\@nil]{%
   \def\tmp{#1}%
   \ifx\tmp\@nnil
     \frac{\ud#2}{\ud#3}%
   \else
     \frac{\ud^{#1}#2}{\ud#3^{#1}}%
   \fi%
 }
+\newcommand{\pdfrac}[3][\@nil]{%
+  \def\tmp{#1}%
+  \ifx\tmp\@nnil
+    \frac{\partial#2}{\partial#3}%
+  \else
+    \frac{\partial^{#1}#2}{\partial#3^{#1}}%
+  \fi%
+}
 \newcommand{\abs}[1]{\left\lvert #1{} \right\rvert}
 
 % Text mode additions