Date: Jan 11, 2013 10:23 PM
Subject: defining an unknown function

Hi all,
I would like to start by defining H = {{\partial_{x,x} L,\partial_{x,y} L},
{\partial_{y,x} L, \partial_{y,y} L}};
where at this stage, the only think i know is that L is of the form L(x,y). This is a Hessian, and I would like to symbolically compute the e-vals and e-vecs. I wanted to know how I should tell mathematica to consider L as L(x,y) ?