Add decision from #2204 - allowing sum/product of matrices with non-i…

…nteger indexing.

Note that the main point of #2204 is not decided as far as I can tell.

chapters/arrays.tex

@@ -402,7 +402,7 @@ \subsection{Reduction Functions and Operators}\doublelabel{reduction-functions-a
 &
 \begin{tabular}{@{}p{10cm}@{}}
 Returns the scalar sum of all the elements of array expression:\\
-\lstinline!A[1,...,1]+A[2,...,1]+....+A[end,...,1]+A[end,...,end]!
+\lstinline!=sum(A[j,k,...]) for j,k,...!
 \end{tabular}\\ \hline
 \begin{tabular}{@{}p{5cm}@{}}
 \lstinline!sum(e(i, ..., j)!\\
@@ -423,7 +423,7 @@ \subsection{Reduction Functions and Operators}\doublelabel{reduction-functions-a
 &
 \begin{tabular}{@{}p{10cm}@{}}
 Returns the scalar product of all the elements of array expression A.\\
-  A[1,...,1]*A[2,...,1]*....*A[end,...,1]*A[end,...,end]
+  \lstinline!=product(A[j,k,...] for j,k,...!
 \end{tabular}\\ \hline
 \begin{tabular}{@{}p{4cm}@{}}
 \lstinline!product(e(i, ..., j)!\\