Update for-statement to refer to for-equation and clarify evaluation. (…

…modelica#2391)

* Update for-statement to refer to for-equation and clarify evaluation.
Closes modelica#2205
Closes modelica#2208

chapters/equations.tex

@@ -103,15 +103,17 @@ \subsection{For-Equations -- Repetitive Equation Structures}\doublelabel{for-equ
 for IDENT in expression loop
 \end{lstlisting}
 
-The \lstinline!expression! of a for-equation shall be a vector expression. It is
-evaluated once for each for-equation, and is evaluated in the scope
+\subsubsection{Explicit Iteration Ranges of For-Equations}\doublelabel{explicit-iteration-ranges-of-for-equations}
+The \lstinline!expression! of a for-equation shall be a vector expression,
+where more general array expressions are treated as vector of vectors or vector of matrices.
+It is evaluated once for each for-equation, and is evaluated in the scope
 immediately enclosing the for-equation. The expression of a for-equation
 shall be a parameter expression. The iteration range of a for-equation
 can also be specified as Boolean or as an enumeration type, see
 \autoref{types-as-iteration-ranges} for more information. The loop-variable (\lstinline!IDENT!) is in scope
-inside the loop-construct and shall not be assigned to. The
-loop-variable has the same type as the type of the elements of the
-vector expression.
+inside the loop-construct and shall not be assigned to.
+For each element of the evaluated vector expression, in the normal order, the loop-variable
+gets the value of that element and that is used to evaluate the body of the for-loop.
 
 {[}\emph{Example}:
 \begin{lstlisting}[language=modelica]
@@ -136,6 +138,7 @@ \subsection{For-Equations -- Repetitive Equation Structures}\doublelabel{for-equ
 \end{lstlisting}
 {]}
 
+
 \subsubsection{Implicit Iteration Ranges of For-Equations}\doublelabel{implicit-iteration-ranges-of-for-equations}
 
 The iteration range of a loop variable may sometimes be inferred from

chapters/statements.tex

@@ -193,12 +193,8 @@ \subsection{For-statement}\doublelabel{for-statement}
 \begin{lstlisting}[language=modelica]
 for IDENT in expression loop
 \end{lstlisting}
-The \lstinline!expression! of a for-statement shall be a vector expression. It is
-evaluated once for each for-statement, and is evaluated in the scope
-immediately enclosing the for-statement. The loop-variable (\lstinline!IDENT!) is in
-scope inside the loop-construct and shall not be assigned to. The
-loop-variable has the same type as the type of the elements of the
-vector expression.
+The rules for for-statements are the same as for for-expressions in \autoref{explicit-iteration-ranges-of-for-equations} -
+except that the \lstinline!expression! of a for-statement is not restricted to a parameter-expression.
 
 {[}\emph{Example}: