Add \, after comma in math

chapters/functions.tex

@@ -1443,7 +1443,7 @@ \subsection{Using the Derivative Annotation}\label{using-the-derivative-annotati
 In the example above \lstinline!zeroDerivative=y! and \lstinline!zeroDerivative=offset! imply that
 \begin{equation*}
 \begin{aligned}
-\udfrac{}{t}\text{\lstinline!f!}(x(t),y(t),o(t))
+\udfrac{}{t}\text{\lstinline!f!}(x(t),\, y(t),\, o(t))
 &= \pdfrac{\text{\lstinline!f!}}{x} \udfrac{x}{t} + \pdfrac{\text{\lstinline!f!}}{y} \udfrac{y}{t} + \pdfrac{\text{\lstinline!f!}}{o} \udfrac{o}{t}\\
 &= \pdfrac{\text{\lstinline!f!}}{x} \udfrac{x}{t} + \pdfrac{\text{\lstinline!f!}}{y} \cdot 0 + \pdfrac{\text{\lstinline!f!}}{o} \cdot 0\\
 &= \pdfrac{\text{\lstinline!f!}}{x} \udfrac{x}{t}\\
@@ -1500,10 +1500,10 @@ \subsection{Using the Derivative Annotation}\label{using-the-derivative-annotati
 \begin{equation*}
 \begin{aligned}
 \udfrac{}{t}\text{\lstinline!fg!}(x(t))
-&= \udfrac{}{t}\text{\lstinline!f!}(x(t),\text{\lstinline!g!}(x(t)))\\
+&= \udfrac{}{t}\text{\lstinline!f!}(x(t),\, \text{\lstinline!g!}(x(t)))\\
 &= \pdfrac{\text{\lstinline!f!}}{x} \udfrac{x}{t} + \pdfrac{\text{\lstinline!f!}}{y} \pdfrac{\text{\lstinline!g!}}{x} \udfrac{x}{t}\\
 &= \left(\pdfrac{\text{\lstinline!f!}}{x} + \pdfrac{\text{\lstinline!f!}}{y} \pdfrac{\text{\lstinline!g!}}{x} \right) \udfrac{x}{t}\\
-&= \text{\lstinline!h!}(x(t),y(t))) \udfrac{x}{t}
+&= \text{\lstinline!h!}(x(t),\, y(t))) \udfrac{x}{t}
 \end{aligned}
 \end{equation*}
 \end{nonnormative}