Update chapters/functions.tex

Co-authored-by: Elena Shmoylova <eshmoylova@users.noreply.github.com>

chapters/functions.tex

@@ -1539,7 +1539,7 @@ \section{Declaring Inverses of Functions}\label{declaring-inverses-of-functions}
 Several inverses are separated by commas.
 
 The function in the \lstinline!inverse! annotation must be an actual inverse.
-This requires that for all valid values of the input arguments of \lstinline!$f_2$($\ldots$, y, $\ldots$)! and $u_k$ being calculated as \lstinline!$u_k$ := $f_2$($\ldots$, y, $\ldots$)! implies
+This requires that $f_2$ is such that, if $u_k$ is calculated as \lstinline!$u_k$ := $f_2$($\ldots$, y, $\ldots$)!, the equality \lstinline!y = $f_1$($\ldots$, $u_k$, $\ldots$)! is satisfied up to a certain precision, for all valid values of the input arguments of \lstinline!$f_2$($\ldots$, y, $\ldots$)!.
 the equality \lstinline!y = $f_1$($\ldots$, $u_k$, $\ldots$)! is satisfied up to a certain precision.
 
 Function $f_1$ can have any number and types of formal parameters with and without default value.