\section{Writing the results: American or French format}\label{sec:format}

The numbers written by \tkzname{tkz-fn} (tick labels, coordinates, results of computations) follow one of the two following conventions:

\begin{center}
\begin{tabular}{lll}
\toprule
& American format (\texttt{us}) & French format (\texttt{fr}) \\
\midrule
decimal separator & $3.14$ & $3{,}14$ \\
thousands separator & $12{,}345$ & $12\,345$ (thin space) \\
intervals & $(a,\,b)$, $[a,\,b]$ & $\mathopen{]}a\,;\,b\mathclose{[}$, $\mathopen{[}a\,;\,b\mathclose{]}$ \\
coordinates & $A(2,\,3)$ & $A(2\,;\,3)$ \\
origin & $0$ & $O$ \\
\bottomrule
\end{tabular}
\end{center}

Thousands are separated only from five digits on: $1234$ but $\tkzFnPrint{12345}$.

\subsection{Choosing the format}

\begin{itemize}
  \item By default, the format is French if the language of \tkzname{babel} is French at the beginning of the document, American otherwise.
  \item The package options force the format: |\usepackage[us]{tkz-fn}| or |\usepackage[fr]{tkz-fn}|.
  \item In the document: |\tkzFnSetup{format=fr}|.
\end{itemize}

\begin{NewMacroBox}{tkzFnSetup}{\marg{options}}
\begin{tabular}{lll}
\toprule
options             & default & definition  \\
\midrule
\TOline{format}{us or fr}{format of the numbers}
\TOline{decimals}{2}{maximum number of decimal places of \tkzcname{tkzFnPrint}}
\TOline{axes}{school}{presentation of the axes: \texttt{school} or \texttt{box}}
\TOline{arrows}{end}{arrows of the axes: \texttt{end}, \texttt{both} or \texttt{none}}
\bottomrule
\end{tabular}
\end{NewMacroBox}

\subsection{Writing a result: \tkzcname{tkzFnPrint}}

\begin{NewMacroBox}{tkzFnPrint}{\oarg{decimals}\marg{Lua expression}}
\emph{Computes the expression and writes the rounded result, without useless zeros. The functions defined with \tkzcname{tkzFnDef} can be used, as well as \texttt{diff(f,x)}, \texttt{integral(f,a,b)} and \texttt{riemann(f,a,b,n,"left")}.}
\end{NewMacroBox}

\begin{NewMacroBox}{tkzFnPrintInterval}{\oarg{oo, cc, oc or co}\marg{a}\marg{b}}
\emph{Writes an interval; \texttt{o} = open, \texttt{c} = closed. The endpoints are Lua expressions or \TeX\ text (\texttt{-\textbackslash infty}).}
\end{NewMacroBox}

\subsection{Example}

\begin{tkzexample}[latex=6cm]
\tkzFnDef{f}{x^2-2*x-1}
\begin{tikzpicture}[scale=.5]
  \tkzFnInit[xmin=-2,xmax=4,
             ymin=-3,ymax=6]
  \tkzFnGrid \tkzFnAxes
  \tkzFnDraw[thick,red](f)
  \tkzFnDefPoint[draw](f,3.5){A}
\end{tikzpicture}

$A\tkzFnPrintCoord(A)$,
$f'(3)=\tkzFnPrint{diff(f,3)}$,
$\tkzFnPrint[4]{f(0.25)}$,
$\tkzFnPrint{1234567.891}$,
$I=\tkzFnPrintInterval[oc]{-\infty}{2.5}$

\tkzFnSetup{format=fr}
$A\tkzFnPrintCoord(A)$,
$f'(3)=\tkzFnPrint{diff(f,3)}$,
$\tkzFnPrint[4]{f(0.25)}$,
$\tkzFnPrint{1234567.891}$,
$I=\tkzFnPrintInterval[oc]{-\infty}{2.5}$
\tkzFnSetup{format=us}
\end{tkzexample}

\subsection{Tick labels in French format}

\begin{tkzexample}[latex=7cm]
\tkzFnSetup{format=fr}
\begin{tikzpicture}[scale=.8]
  \tkzFnInit[xmin=0,xmax=2,xstep=.25,
             ymin=0,ymax=20000,ystep=4000]
  \tkzFnGrid
  \tkzFnAxes
  \tkzFnDraw[blue,thick]{5000*x^2}
\end{tikzpicture}
\tkzFnSetup{format=us}
\end{tkzexample}

\endinput