Dear Firedrakers, I'm evaluating the Jacobian dF/du of my nonlinear function F by, J = derivative(F,u) This seems to evaluate with zero u: dF(0)/du. What I would like to have is dF(u0)/du, the Jacobian evaluated at the initial conditions. How would I do that? Thank you! Henrik -- Dipl.-Math. Henrik Büsing Institute for Applied Geophysics and Geothermal Energy E.ON Energy Research Center RWTH Aachen University ------------------------------------------------------ Mathieustr. 10 | Tel +49 (0)241 80 49907 52074 Aachen, Germany | Fax +49 (0)241 80 49889 ------------------------------------------------------ http://www.eonerc.rwth-aachen.de/GGE hbuesing@eonerc.rwth-aachen.de ------------------------------------------------------