FancyTex

http://theoval.cmp.uea.ac.uk/~nlct/latex/novices/node64.html

\newcommand{\pderiv}[2]{\frac{\partial #1}{\partial #2}}
\newcommand{\e}{\mathrm{e}}

\begin{displaymath}
\pderiv{^2\mathcal{L}}{{z_i^\rho}^2} =
-\pderiv{\rho_i}{z_i^\rho}
\left(
  \pderiv{v_i}{\rho_i} \frac{\e^{v_i}}{1-\e^{v_i}}
  + v_i \frac{\e^{v_i}\pderiv{v_i}{\rho_i}(1-\e^{v_i})
             +\e^{2v_i}\pderiv{v_i}{\rho_i}}{(1-\e^{v_i})^2}
\right)
\end{displaymath}