[GiNaC-list] Differentiation of a function with respect to a tensor

Hi everyone, I've recently discovered GiNaC and I'm really excited about its capabilities. There is one thing that I would like to know if it is able to do that I haven't found in the tutorial.pdf or in any other place that I've searched. I would like to know if, given a function \Psi=\Psi(E), like the strain energy function for the St. Venant-Kirchhoff material \Psi(E) = 0.5 * \lambda * (tr E)^2 + \mu E:E is it possible to differentiate it with respect to E, that is i would like to compute \frac{\partial \Psi}{\partial E}. If this is possible, could someone please send some examples or maybe point to which classes should I use to do that? That's all for now. Many thanks in advance. Best regards, Bernardo M. R.