Make sagetex work together with pgfplots

[student-sx]

It would be useful to provide a way to "export" a function defined in sage such that you can use it with pgfplots directly. There is already a suggestion on stackexchange (http://tex.stackexchange.com/questions/220491/how-to-pass-a-function-defined-in-sagetex-to-pgfplots), where I proposed to have something like a sageraw command which you could use to pass the function as in the example below. Another idea would be to provide a command \expfct(funktion,texcommand) which "saves" the function under the name texcommand such that it is available from the main document for pgfplots.

\documentclass{article}
\usepackage{pgfplots}
\usepackage{sagetex}

\begin{document}

\begin{sagesilent}
  f(x) = 2*sin(x^2)
\end{sagesilent}

$f(x) = \sage{f(x)}$

\begin{center}
  \begin{tikzpicture}
    \begin{axis}[no markers, samples=100]
%      \addplot gnuplot {\sageraw{f(x)}};
      %should be the same as
      \addplot gnuplot {2*sin(x^2)};
    \end{axis}
  \end{tikzpicture}
\end{center}

\end{document}