Update chapters/lexicalstructure.tex

chapters/lexicalstructure.tex

@@ -251,7 +251,7 @@ \subsection{Units of Literal Constants}\label{units-literal-constants}
 
 Literal \lstinline!Real! and \lstinline!Integer! constants are implicitly assumed to have a dimensionless unit if they appear in expressions containing variables, parameters, or constants that have a non-empty \lstinline!unit! attribute string, or function calls that have a non-empty \lstinline!unit! attribute of the output variable. The same rule applies to function call inputs.
 
-The inputs of transcendental built-in functions such as \lstinline!sin()!, \lstinline!cos()!, \lstinline!exp()!, etc., should have a dimensionless unit (e.g., \lstinline!"1"! or \lstinline!"rad"!) if they involve expressions containing variables, parameters, or constants that have a non-empty unit attribute string.
+The inputs of the elementary mathematical functions defined in \cref{built-in-mathematical-functions-and-external-built-in-functions} such as \lstinline!sin()!, \lstinline!cos()!, \lstinline!exp()!, etc., should have a dimensionless unit (e.g., \lstinline!"1"! or \lstinline!"rad"!) if the unit string of the input is non-empty. Function \lstinline!atan2(y,x)! should be treated as  \lstinline!atan(x/y)! for dimensional consistency checking purposes.
 Their outputs are also implicitly assumed to have a dimensionless unit if they are called within expressions containing variables, parameters, or constants that have a non-empty \lstinline!unit! attribute string.
 
 \begin{nonnormative}