\documentclass{article}<br /> <br />
\usepackage[latin1]{inputenc}<br />
\usepackage{tikz}<br /> <br />
% GNUPLOT required<br />
\begin{document}<br />
\pagestyle{empty}<br /> <br /> <br />
\begin{tikzpicture}[domain=0:4]<br />
    \draw[very thin,color=gray] (-0.1,-1.1) grid (3.9,3.9);<br />
    \draw[->] (-0.2,0) -- (4.2,0) node[right] {$x$};<br />
    \draw[->] (0,-1.2) -- (0,4.2) node[above] {$f(x)$};<br />
    \draw[color=red] plot[id=x] function{x} <br />
        node[right] {$f(x) =x$};<br />
    \draw[color=blue] plot[id=sin] function{sin(x)} <br />
        node[right] {$f(x) = \sin x$};<br />
    \draw[color=orange] plot[id=exp] function{0.05*exp(x)} <br />
        node[right] {$f(x) = \frac{1}{20} \mathrm e^x$};<br />
\end{tikzpicture}<br /> <br /> <br />
\end{document}<br />