# Plots in TikZ don't work

I want to do some plots using TikZ, however the following code doesn't work:

\documentclass{minimal}
\usepackage{amsmath}

\usepackage{pgf,tikz}%
\begin{document}
\begin{tikzpicture}
\draw[->] (-3,0) -- (2.2,0) node[right] {$x$}; %
\draw[->] (0,-0.5) -- (0,3.2) node[above] {$y$};%
\draw plot (\x,{\x^2});%
\end{tikzpicture}
\end{document}


Any idea what's wrong?

How to plot functions like x \mapsto a^x (a > 0)?

Edit: Thanks for the patch, however ploting 2^x doesn't work, I get the following picture using Jakes answer:

-
Could you please change the image to not include a large white space on top? Also please describe your issue more precise. "Doesn't work" is not very descriptive. –  Martin Scharrer May 19 '11 at 19:11
possible duplicate of How can I work around this TikZ bug? –  Jake May 19 '11 at 19:19
Could you add the code you used to generate the image? –  Jake May 19 '11 at 19:47
@Jake: I copied exactly your code from below. –  student May 19 '11 at 20:23

As Martin Scharrer pointed out, this is a bug that Hendrik Vogt has provided a patch for in his answer to the question How can I work around this TikZ bug?

On a side note: tikz loads pgf automatically, so you don't need to load it explicitly.

\documentclass{article}

\usepackage{tikz}%

\makeatletter
\def\tikz@scan@no@calculator#1(#2){%
\patch@tikz(#2)%
\expandafter\tikz@@scan@@no@calculator\expandafter#1\tikz@temp
}
\def\patch@tikz(#1,#2){%
{\expandafter\let\expandafter\save@tikz@plot@var\tikz@plot@var
\expandafter\def\tikz@plot@var{(\save@tikz@plot@var)}%
\xdef\tikz@temp@i{#1}%
\xdef\tikz@temp@ii{#2}%
}%
\edef\tikz@temp{({\tikz@temp@i},{\tikz@temp@ii})}%
}
\makeatother

\begin{document}
\begin{tikzpicture}
\draw[->] (-2.2,0) -- (2.2,0) node[right] {$x$}; %
\draw[->] (0,-0.5) -- (0,3.2) node[above] {$y$};%
\draw [domain=-2:2,orange] plot (\x,\x^2);
\draw [domain=-2:2,blue] plot (\x,2^\x);%
\end{tikzpicture}
\end{document}


-
Is this that PGF bug for v2.1 (or was it v2.x)? –  Martin Scharrer May 19 '11 at 19:10
@Martin: Indeed, you're right. Thanks for pointing that out. So this should be closed as a duplicate? –  Jake May 19 '11 at 19:18
Thanks, however plotting 2^\x seems not to work –  student May 19 '11 at 19:29
@user4011: It does for me, see the edited answer. Maybe you'se using an old version of TikZ? –  Jake May 19 '11 at 19:37
@Jake: How to find out the tikz version? See my edit above –  student May 19 '11 at 19:46