Add missing math styling on array concatenation helper variables

chapters/arrays.tex

@@ -662,8 +662,8 @@ \subsection{Array Concatenation}\doublelabel{array-concatenation}
   $k$ has to characterize an existing dimension, i.e., $1 \leq k \leq \text{\lstinline!ndims(A)!} = \text{\lstinline!ndims(B)!} = \text{\lstinline!ndims(C)!}$; $k$ shall be a parameter expression of \lstinline!Integer! type.
 \item
   Size matching: Arrays \lstinline!A!, \lstinline!B!, \lstinline!C!, \ldots must have identical array sizes
-  with the exception of the size of dimension $k$, i.e., \lstinline!size(A,j)! =
-  \lstinline!size(B,j)!, for $1 \leq j \leq \text{\lstinline!ndims(A)!}$ and $j \neq k$.
+  with the exception of the size of dimension $k$, i.e., \lstinline[mathescape=true]!size(A, $j$)! =
+  \lstinline[mathescape=true]!size(B, $j$)!, for $1 \leq j \leq \text{\lstinline!ndims(A)!}$ and $j \neq k$.
 \end{itemize}
 
 \begin{example}