Dear all, Ok. Maybe this is the way to go: As before, I have a function temp(p,h), which shall return temperature dependent on pressure and enthalpy. I insert UFL representations of p and h into temp(,). Then I'm doing a p = assemble(p).dat.data[0] h = assemble(h).dat.data[1] Now, I execute some operations on the arrays. In the end I want to have the UFL representation of temp (the same as what I inserted as p and h). So how do I get the UFL representation back from the array? 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 ------------------------------------------------------