Normal Gauss Distribution

\documentclass{article}[14pt,a4paper] % Comment the following line to NOT allow the usage of umlauts
%\usepackage[utf8]{inputenc}
%\useusepackage[utf8]{imputenc} %\usepackage[a4paper, lmargin=2cm, rmargin=2cm, bottom=2cm]{geometry}
\usepackage{color} % Uncomment the following line to allow the usage of graphics (.png, .jpg)
\usepackage{multicol} \usepackage{verbatim} \usepackage{graphicx} \usepackage{amsmath} \usepackage[all]{xy} \usepackage{pst-all} \usepackage{tikz} \usepackage{gnuplottex}  \usepackage{pst-pdf}
\usepackage{mathtools,amssymb}
\usepackage{xcolor}
%\usepackage{chronology}
%\usepackage{pst-solides3d}
\tikzset{flippedeventlabel/.append style={align=center}} \usetikzlibrary{datavisualization} \usetikzlibrary{matrix.skeleton} \usetikzlibrary[shapes,arrows,positioning,fit,backgrounds,intersections,shadows,calc] \usetikzlibrary{positioning} \usetikzlibrary{decorations.text} \usetikzlibrary{decorations.pathmorphing}
\usepackage{pgfplots} \pgfplotsset{width=10cm,compat=1.9}
%\psset{viewpoint=10 18 60 rtp2xyz,Decran=10,fontsize=10,unit=0.65cm}
\usetikzlibrary{patterns}
\pgfmathdeclarefunction{gauss}{2}{\pgfmathparse{1/(#2*sqrt(2*pi))*exp(-((x-#1)^2)/(2*#2^2))} }
% Start the document
\begin{document}
\begin{center}



\begin{tikzpicture}
\begin{pgfonlayer}{background} \path[fill=black,rounded corners]
(-1,-1) rectangle (10,5);
\end{pgfonlayer}



\begin{axis}[white,no markers, domain=0:10, samples=100, axis lines*=left, xlabel=Normal, ylabel=axis $y$, height=5cm, width=10cm, xticklabels={0, $-\infty$, -z, -z/2, 0, z/2, z, $+\infty$, 0}, ytick=\empty, enlargelimits=false, clip=false, axis on top]
\addplot [very thick, green, domain=-3:3] {gauss(0,1)} \closedcycle;

\end{axis}
\draw node at (4,1){\large\textcolor{white}{$f(z) = \frac{1}{\sqrt{2\pi}}\ \mathbf{e}^{(\frac{z-\mu}{\sigma})^2}$}};
\end{tikzpicture}
\end{center}
%Uncomment the following two lines if you want to have a bibliography1 %\bibliographystyle{alpha} %\bibliography{document} %\begin{thebibliography}{document} %\renewcommand %\refname{BIBLIOGRAFIA} %\bibitem{Baz} \textit{Bazaraa, M.S., J.J. %Jarvis} y \textit{H.D. Sheraly}, %\textit{Programación lineal y flujo de redes}, %Segunda Edición. Limusá, México, DF. 2004. %\end{thebibliography}
\end{document}