[GiNaC-list] Symbolic functions with multiple outputs

[Chris Dams]

Dear John,

On Thu, 8 Sep 2005, John Pye wrote:

> >In the list case, perhaps what you really would want to have is a
> >symbolic function water_variables(p,h) that does not evalutate further
> >but can be used to hold pressure and enthalpy as results.
>
> Sorry, I don't understand what you mean here?

DECLARE_FUNCTION_2P(water_variables);
REGISTER_FUNCTION(water_variables,dummy());

ex f=water_variables(p,h);

> By evaluating these at the same time in my final numerical evaluation
> stage, I can optimise a bit on the evaluation of the power series which
> is used to provide the steam properties I'm using, see
> http://pye.dyndns.org/freesteam/

In the case with the water_variables function you could supply your own
function for the numerical evalutation of such a function and you could
use your optimisations.

Best wishes,
Chris