%
% nonanalytic.tex -- nicht analytische reelle C^\infty-Funktion
%
% (c) 2021 Prof Dr Andreas Müller, OST Ostschweizer Fachhochschule
%
\documentclass[tikz]{standalone}
\usepackage{amsmath}
\usepackage{times}
\usepackage{txfonts}
\usepackage{pgfplots}
\usepackage{csvsimple}
\usetikzlibrary{arrows,intersections,math}
\begin{document}
\def\skala{1}
\begin{tikzpicture}[>=latex,thick,scale=\skala]

\draw[color=red,line width=1.4pt] plot[domain=0.01:2.5,samples=100]
	({2*\x},{4*exp(-1/(\x*\x))});
\draw[color=red,line width=1.4pt] plot[domain=0.01:2.5,samples=100]
	({-2*\x},{4*exp(-1/(\x*\x))});

\draw (2,-0.1) -- (2,0.1);
\draw (4,-0.1) -- (4,0.1);
\draw (-2,-0.1) -- (-2,0.1);
\draw (-4,-0.1) -- (-4,0.1);

\node at (2,0) [below] {$1$};
\node at (4,0) [below] {$2$};
\node at (-2,0) [below] {$-1$};
\node at (-4,0) [below] {$-2$};

\draw (-0.1,4) -- (0.1,4);
\node at (-0.1,4) [left] {$1$};

\draw[->] (-5.1,0) -- (5.4,0) coordinate[label={$x$}];
\draw[->] (0,-0.1) -- (0,4.4) coordinate[label={right:$y$}];

\end{tikzpicture}
\end{document}