\documentclass{article}
% translate with >> pdflatex -shell-escape <file>

% This file is an extract of the PGFPLOTS manual, copyright by Christian Feuersaenger.
% 
% Feel free to use it as long as you cite the pgfplots manual properly.
%
% See
%   http://pgfplots.sourceforge.net/pgfplots.pdf
% for the complete manual.
%
% Any required input files (for <plot table> or <plot file> or the table package) can be downloaded
% at
% http://www.ctan.org/tex-archive/graphics/pgf/contrib/pgfplots/doc/latex/
% and
% http://www.ctan.org/tex-archive/graphics/pgf/contrib/pgfplots/doc/latex/plotdata/

\usepackage{pgfplots}
\pgfplotsset{compat=newest}

\pagestyle{empty}

\begin{document}
\begin{tikzpicture}
	\pgfplotsset{small}
	\matrix {
		\begin{axis}
			\addplot {x};
		\end{axis}
		&
		% differently large labels are aligned automatically:
		\begin{axis}[ylabel={$f(x)=x^2$},ylabel style={font=\Huge}]
			\addplot {x^2};
		\end{axis}
		\\
		%
		\begin{axis}[xlabel=$x$,xlabel style={font=\Huge}]
			\addplot {x^3};
		\end{axis}
		&
		\begin{axis}
			\addplot {x^4};
		\end{axis}
		\\
	};
\end{tikzpicture}
\end{document}
