\section{Symboles} Certains ajoutent aux courbes des symboles afin de donner des indications supplémentaires au lecteur. Voici quelques exemples possibles~: \begin{tikzpicture} \draw[thick,(-)](0,0)--(2,2); \draw[thick,o-o](2,0)--(4,2); \draw[thick,)-(](4,0)--(6,2); \draw[thick,*-*](6,0)--(8,2); \end{tikzpicture} \newcommand{\cred}[1]{{\color{red}#1}} \newcommand{\cgreen}[1]{{\color{green!50!black}#1}} \newcommand{\cblue}[1]{{\color{blue}#1}} L'exemple suivant est de \tkzname{Simon Schläpfer}~: On veut tracer \[ y=\left\{\begin{array}{ll} \cred{8-1.5x}&,\text{if }x<2\\ \cblue{4}&,\text{if }2 \leq x \leq 3\\ \cgreen{2x-4}&,\text{if } x>3 \end{array} \right. \] \begin{center} \begin{tkzexample}[vbox] \begin{tikzpicture} \tkzInit[xmin=-1,xmax=6,ymin=0,ymax=10,xstep=1,ystep=1] \tkzGrid[color=gray] \tkzAxeXY \tkzFct[{-[},color=red,domain =-1:2,samples=2]{8-1.5*\x} \tkzFct[{[-]},color=blue,domain =2:3,samples=2]{4} \tkzFct[{]-},color=green!50!black,domain =3:6,samples=2]{2*\x-4} \end{tikzpicture} \end{tkzexample} \end{center} \endinput