Hi again Just reading the GiNaC 1.3.1 manual, in the section about adding new symbolic functions, section 6.2 Is it possible to create symbolic functions that have multiple, matrix, or list outputs? Is there a way to assign the outputs of a multiple-valued symbolic function to elements of a list? lst(a,b,c) = three_valued_function(d,e); For example, a case where one might want to do this sort of thing would be evaluation of fluid properties, like so lst(p,h) = pressure_and_enthalpy_of_water(T, rho); When finally evaluating this numerically, eg once T and rho are known, having this as one symbolic function allows some intrinsic optimisation of calls to the thermodynamic property calculation routines. Thanks for your help, and sorry for the stream of silly questions... Cheers JP -- John Pye School of Mechanical and Manufacturing Engineering The University of New South Wales Sydney NSW 2052 Australia t +61 2 9385 5127 f +61 2 9663 1222 mailto:john.pye_AT_student_DOT_unsw.edu.au http://pye.dyndns.org/